| 1. |
- Chan, Cangel Pui Yee, et al.
(author)
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Evidence-Based Point-of-Care Diagnostics: Current Status and Emerging Technologies
- 2013
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In: Annual Review of Analytical Chemistry. - : Annual Reviews. - 1936-1327 .- 1936-1335. - 9780824344061 ; 6, s. 191-211
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Journal article (peer-reviewed)abstract
- Point-of-care (POC) diagnostics brings tests nearer to the site of patient care. The turnaround time is short, and minimal manual interference enables quick clinical management decisions. Growth in POC diagnostics is being continuously fueled by the global burden of cardiovascular and infectious diseases. Early diagnosis and rapid initiation of treatment are crucial in the management of such patients. This review provides the rationale for the use of POC tests in acute coronary syndrome, heart failure, human immunodeficiency virus, and tuberculosis. We also consider emerging technologies that are based on advanced nanomaterials and microfluidics, improved assay sensitivity, miniaturization in device design, reduced costs, and high-throughput multiplex detection, all of which may shape the future development of POC diagnostics.
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| 2. |
- Cheung, Kitt, et al.
(author)
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Fabrication of Protein Microparticles and Microcapsules with Biomolecular Tools
- 2018
-
In: Zeitschrift fur physikalische Chemie (Munchen. 1991). - : WALTER DE GRUYTER GMBH. - 0942-9352 .- 2196-7156. ; 232:5-6, s. 759-771
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Journal article (peer-reviewed)abstract
- Microparticles have attracted much attention for medical, analytical and biological applications. Calcium carbonate (CaCO3) templating method with the advantages of having narrow size distribution, controlled morphology and good biocompatibility that has been widely used for the synthesis of various protein-based microparticles. Despite CaCO3 template is biocompatible, most of the conventional methods to create stable protein microparticles are mainly driven by chemical crosslink reagents which may induce potential harmful effect and remains undesirable especially for biomedical or clinical applications. In this article, we demonstrate the fabrication of protein microparticles and microcapsules with an innovative method using biomolecular tools such as enzymes and affinity molecules to trigger the assembling of protein molecules within a porous CaCO3 template followed by a template removal step. We demonstrated the enzyme-assisted fabrication of collagen microparticles triggered by transglutaminase, as well as the affinity-assisted fabrication of BSA-biotin avidin microcapsules triggered by biotin-avidin affinity interaction, respectively. Based on the different protein assemble mechanisms, the collagen microparticles appeared as a solid-structured particles, while the BSA-biotin avidin microcapsules appeared as hollow-structured morphology. The fabrication procedures are simple and robust that allows producing protein microparticles or microcapsules under mild conditions at physiological pH and temperature. In addition, the microparticle morphologies, protein compositions and the assemble mechanisms were studied. Our technology provides a facile approach to design and fabricate protein microparticles and microcapsules that are useful in the area of biomaterials, pharmaceuticals and analytical chemistry.
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| 3. |
- Cheung, Kwan Yee, et al.
(author)
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Reusable optical bioassay platform with permeability-controlled hydrogel pads for selective saccharide detection
- 2008
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In: Analytica Chimica Acta. - : Elsevier. - 0003-2670 .- 1873-4324. ; 607:2, s. 204-210
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Journal article (peer-reviewed)abstract
- A reusable optical bioassay platform using permeability-controlled hydrogel pads for selective saccharide detection has been developed. An optical glucose detection assay based on fluorescence resonance energy transfer (FRET) between dye-labeled dextran and Concanavalin A (ConA) was incorporated into hydrogel pads by entrapment. The hydrogel pads are constructed from hemispherical hydrogel attached onto hydrophobic surfaces of a microtiter plate. The resulted hemispherical hydrogel pads entrapping the sensing biological materials were further surface coated with polyelectrolyte multilayers through a Layer-by-Layer (LbL) self-assembly process to create a permeability-controlled membrane with nanometer thickness. The selective permeable LbL film deposited on the hydrogel surface allows small molecular weight analytes to diffuse into the hydrogel pads while the large molecular weight sensing biological molecules are immobilized. An encapsulation efficiency of 75% for the ConA/Dextran complex within the coated hydrogel pads was achieved and no significant leakage of the complex was observed. Glucose calibration curve with linear range from 0 to 10 mM glucose was obtained. Selective permeability of the hydrogel pads has been demonstrated by measurement of saccharides with various molecular weights. The LbL hydrogel pads could selectively detect monosaccharides (glucose, MW = 180) and disaccharides (sucrose, MW = 342) while polysaccharides (dextran, MW ∼ 70 kDa) cannot diffuse through the LbL layer and are excluded. LbL hydrogel pads allow regeneration of the FRET system with good signal reproducibility of more than 90% to construct a reusable and reagentless optical bioassay platform.
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| 4. |
- Cheung Mak, Wing, et al.
(author)
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Surface-Engineered Contact Lens as an Advanced Theranostic Platform for Modulation and Detection of Viral Infection
- 2015
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In: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 7:45, s. 25487-25494
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Journal article (peer-reviewed)abstract
- We have demonstrated an entirely new concept of a wearable theranostic device in the form of a contact lens (theranostic lens) with a dual-functional hybrid surface to modulate and detect a pathogenic attack, using a the corneal HSV serotype-1 (HSV-1) model. The theranostic lenses were constructed using a facile layer-by-layer surface engineering technique, keeping the theranostic lenses with good surface wettability, optically transparency, and nontoxic toward human corneal epithelial cells. The theranostic lenses were used to capture and concentrate inflammatory cytokines such as interleukin-1 alpha (IL-1 alpha), which is upregulated during HSV-1 reactivation, for sensitive, noninvasive diagnostics. The theranostic lens also incorporated an antiviral coating to serve as a first line of defense to protect patients against disease. Our strategy tackles major problems in tear diagnostics that are mainly associated with the sampling of a relatively small volume of fluid and the low concentration of biomarkers. The theranostic lenses show effective anti-HSV-1 activity and good analytical performance for the detection of IL-1a, with a limit of detection of 1.43 pg mL(-1) and a wide linear range covering the clinically relevant region. This work offers a new paradigm for wearable noninvasive healthcare devices combining diagnosis and protection against disease, while supporting patient compliance. We believe that this approach holds immense promise as a next-generation point-of-care and decentralized diagnostic/theranostic platform for a range of biomarkers.
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| 5. |
- Eriksson, E., et al.
(author)
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Geometric Flow Control Lateral Flow Immunoassay Devices (GFC-LFIDs): A New Dimension to Enhance Analytical Performance
- 2019
-
In: Research (Washington, D.C.). - : American Association for the Advancement of Science. - 2639-5274.
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Journal article (peer-reviewed)abstract
- The nitrocellulose (NC) membrane based lateral flow immunoassay device (LFID) is one of the most important and widely used biosensor platforms for point-of-care (PoC) diagnostics. However, the analytical performance of LFID has limitations and its optimization is restricted to the bioassay chemistry, the membrane porosity, and the choice of biolabel system. These bottom neck technical issues resulted from the fact that the conventional LFID design principle has not evolved for many years, which limited the LFID for advanced biosensor applications. Here we introduce a new dimension for LFID design and optimization based on geometric flow control (GFC) of NC membranes, leading to highly sensitive GFC-LFID. This novel approach enables comprehensive flow control via different membrane geometric features such as the width (w) and the length (l) of a constriction, as well as its input angle (?1) and output angle (?2). The GFC-LFID (w=0.5 mm, l=7 mm, ?1= 60, ?2= 45) attained a 10-fold increase in sensitivity for detection of interleukin-6 (IL-6), compared with conventional LFID, whereas reducing by 10-fold the antibody consumption. The GFC-LFID detects IL-6 over a linear range of 0.1-10?ng/mL with a limit of detection (LoD) of 29?pg/mL, which even outperforms some commercial IL-6 LFIDs. Such significant improvement is attained by pure geometric control of the NC membrane, without additives, that only relaying on a simple high throughput laser ablation procedure suitable for integration on regular large-scale manufacturing of GFC-LFIDs. Our new development on GFC-LFID with the combination of facile scalable fabrication process, tailored flow control, improved analytical performance, and reduced antibodies consumption is likely to have a significant impact on new design concept for the LFID industry.
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| 6. |
- Ghani, Mozhdeh, et al.
(author)
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Cross-linked superfine electrospun tragacanth-based biomaterial as scaffolds for tissue engineering
- 2016
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In: European Cells & Materials. - Davos, Switzerland : AO Research Institute Davos. - 1473-2262. ; 31:Suppl. 1, s. 204-204
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Journal article (peer-reviewed)abstract
- Natural polymer-based nanofibrous structures promote cell adhesion and proliferation due to their high surface area/volume ratio, high porosity, and similarity to native extracellular matrix in terms of both chemical composition and physical structure. Gum tragacanth (Tg) is a natural polysaccharides obtained from plants. It is a biocompatible, biodegradable and anionic polysaccharides that has been used extensively as an emulsifier in food and pharmaceutical industries. Despite, its good rheological properties and compatibility, the potential biomedical applications of Tg have not been fully investigated. The objective of the present study was to explore the feasibility of combining Tg with gelatin to fabricate a scaffold that serves as a simple collagen-glycosaminoglycans analog for tissue engineering applications, e.g. as a scaffold for human skin epithelial cells.
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| 7. |
- Lademann, J., et al.
(author)
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Triggered release of model drug from AuNP-doped BSA nanocarriers in hair follicles using IRA radiation
- 2016
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In: Acta Biomaterialia. - : ELSEVIER SCI LTD. - 1742-7061 .- 1878-7568. ; 30, s. 388-396
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Journal article (peer-reviewed)abstract
- Recent advances in the field of dermatotherapy have resulted in research efforts focusing on the use of particle-based drug delivery systems for the stimuli-responsive release of drugs in the skin and skin appendages, i.e. hair follicles and sebaceous glands. However, effective and innocuous trigger mechanisms which result in the release of the drugs from the nanocarriers upon reaching the target structures are still lacking. For the first time, the present study demonstrated the photo-activated release of the model drug fluorescein isothiocyanate (FITC) from topically applied gold nanoparticle-doped bovine serum albumin (AuNPs-doped BSA) particles (approx. 545 nm) using water-filtered infrared A (IRA) radiation in the hair follicles of an ex vivo porcine skin model. The IRA radiation-induced plasmonic heating of the AuNPs results in the partial decomposition or opening of the albumin particles and release the model drug, while control particles without AuNPs show insignificant release. The results demonstrate the feasibility of using IRA radiation to induce release of encapsulated drugs from plasmonic nanocarriers for the targeting of follicular structures. However, the risk of radiation-induced skin damage subsequent to repeated applications of high infrared dosages may be significant. Future studies should aim at determining the suitability of lower infrared A dosages, such as for medical treatment regimens which may necessitate repeated exposure to therapeutics. Statement of significance Follicular targeting using nanocarriers is of increasing importance in the prophylaxis and treatment of dermatological or other diseases. For the first time, the present study demonstrated the photo activated release of the model drug fluorescein isothiocyanate (FITC) from topically applied gold nanoparticle-doped bovine serum albumin (AuNPs-doped BSA) particles using water-filtered infrared A (IRA) radiation in the hair follicles of an ex vivo porcine skin model. The results demonstrate the feasibility of using wIRA radiation to induce release of encapsulated drugs for the targeting of follicular structures, and provide a new vision on the development of optically addressable delivery systems for controlled release of drugs in the skin and skin appendages, i.e. hair follicles and sebaceous glands. (C) 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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| 8. |
- Mak, Wing Cheung, et al.
(author)
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Diffusion controlled and temperature stable microcapsule reaction compartments for high throughput microcapsule-PCR
- 2008
-
In: Advanced Functional Materials. - : John Wiley & Sons. - 1616-301X .- 1616-3028. ; 18:19, s. 2930-2937
-
Journal article (peer-reviewed)abstract
- A novel approach to perform a high number of individual polymerase chain reactions (PCR) in microcapsule reaction compartments, termed “Microcapsule-PCR” was developed. Temperature stable microcapsules with a selective permeable capsule wall were constructed by matrix-assisted layer-by-layer (LbL) Encapsulation technique. During the PCR, small molecular weight building blocks – nucleotides (dNTPs) were supplied externally and diffuse through the permeable capsule wall into the interior, while the resulted high molecular weight PCR products were accumulated within the microcapsule. Microcapsules (∼110.8 µm average diameter) filled with a PCR reaction mixture were constructed by an emulsion technique having a 2% agarose core and a capsule formed by LbL coating with poly(allylamine-hydrochloride) and poly(4-styrene-sulfonate). An encapsulation efficiency of 47% (measured for primer-FITC (22 bases)) and 98% PCR efficiency was achieved. Microcapsules formed by eight layers of polyelectrolyte and subjected to PCR cycling (up to 95 °C) demonstrated good temperature stability without any significantly changes in DNA retention yield and microcapsule morphology. A multiplex Microcapsule-PCR experiment demonstrated that microcapsules are individual compartment and do not exchange templates or primers between microcapsules during PCR cycling.
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| 9. |
- Mak, Wing Cheung, et al.
(author)
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Electrochemical bioassay utilizing encapsulated electrochemical active microcrystal biolabels
- 2005
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In: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 77:9, s. 2835-2841
-
Journal article (peer-reviewed)abstract
- A new approach to perform electrochemical immunoassay based on the utilization of encapsulated microcrystal was developed. The microcrystal labels create a “supernova effect” upon exposure to a desired releasing agent. The microcrystal cores dissolve, and large amounts of signal-generating molecules diffuse across the capsule wall into the outer environment. Layer-by-Layer (LbL) technology was employed for the encapsulation of electrochemical signal-generating microcrystals (ferrocene microcrystals). The encapsulated microcrystals were conjugated with antibody molecules through the adsorption process. The biofunctionalized microcrystals were utilized as a probe for immunoassays. The microcrystal-based label system provided a high-signal molecule to antibody (S/P) ratio of 104−105. Microcrystal biolabels with different antibody surface coverage (1.60−5.05 mg m-2) were subjected to a solid-phase immunoassay for the detection of mouse immunoglobulin G (M-IgG) molecules. The microcrystal-based immunoassay for the detection of M-IgG performed with microcrystals having antibody surface coverage of 5.05 mg m-2 showed a sensitivity of 3.93 nA μg-1 L-1 with a detection limit of 2.82 μg L-1.
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| 10. |
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| 11. |
- Mak, Wing Cheung, et al.
(author)
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Thermo-rheological responsive microcapsules for time-dependent controlled release of human mesenchymal stromal cells
- 2017
-
In: Biomaterials Science. - : ROYAL SOC CHEMISTRY. - 2047-4830 .- 2047-4849. ; 5:11, s. 2241-2250
-
Journal article (peer-reviewed)abstract
- Human mesenchymal stromal cells (hMSCs) are adult-source cells that have been extensively evaluated for cell-based therapies. hMSCs delivered by intravascular injection have been reported to accumulate at the sites of injury to promote tissue repair and can also be employed as vectors for the delivery of therapeutic genes. However, the full potential of hMSCs remains limited as the cells are lost after injection due to anoikis and the adverse pathologic environment. Encapsulation of cells has been proposed as a means of increasing cell viability. However, controlling the release of therapeutic cells over time to target tissue still remains a challenge today. Here, we report the design and development of thermo-rheological responsive hydrogels that allow for precise, time dependent controlled-release of hMSCs. The encapsulated hMSCs retained good viability from 76% to 87% dependent upon the hydrogel compositions. We demonstrated the design of different blended hydrogel composites with modulated strength (S parameter) and looseness of hydrogel networks (N parameter) to control the release of hMSCs from thermoresponsive hydrogel capsules. We further showed the feasibility for controlled-release of encapsulated hMSCs within 3D matrix scaffolds. We reported for the first time by a systematic analysis that there is a direct correlation between the thermo-rheological properties associated with the degradation of the hydrogel composite and the cell release kinetics. This work therefore provides new insights into the further development of smart carrier systems for stem cell therapy.
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| 12. |
- Mousavisani, Seyedeh Zeinab, et al.
(author)
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Integrating an ex-vivo skin biointerface with electrochemical DNA biosensor for direct measurement of the protective effect of UV blocking agents
- 2019
-
In: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 128, s. 159-165
-
Journal article (peer-reviewed)abstract
- Skin cancer is the most frequent kind of cancer in white people in many parts of the world. UV-induced DNA damage and genetic mutation can subsequently lead to skin cancer. Therefore development of new biosensing strategies for detection of UV-induced DNA damage is of great importance. Here we demonstrate a novel combination of an ex-vivo skin biointerface and an electrochemical DNA sensor for the direct detection of UV induced DNA damage and investigation the protective effect of various UV blockers (Zinc-oxide (ZnO), titanium-dioxide (TiO) nanoparticles (NPs) and sunscreens) against DNA damage. A diazonium modified screen-printed carbon electrode immobilized with a DNA sequence related to the p53 tumour suppressor gene, the most commonly affected gene in human UV-induced skin cancer, was applied as an electrochemical DNA sensor. Electrochemical impedance spectroscopy (EIS) was employed for the detection of DNA damage induced by UV-A radiation by following the changes in charge transfer resistance (R). The protective effects of UV blockers applied onto a pig skin surface (a suitable model representing human skin) were successfully detected by the DNA sensor. We observed that the naked skin has little UV protection showing an 18.2% decreases in ∆R/R values compared to the control, while applying both NPs and NP-formulated sunscreens could significantly reduce DNA damage, resulting in a decrease in ∆R/R values of 67.1% (ZnO NPs), 77.2% (TiO NPs), 77.1% (sunscreen 1) and 92.4% (sunscreen 2), respectively. Moreover, doping moisturising cream with NPs could provide a similar DNA protective effect. This new method is a biologically relevant alternative to animal testing and offers advantages such as fast, easy and inexpensive processing, in addition to its miniaturised dimension, and could be used for a range of applications in other sources of DNA damage and the protective effect of different UV blocking agents and other topical formulations.
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| 13. |
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| 14. |
- Patzelt, Alexa, et al.
(author)
-
Do nanoparticles have a future in dermal drug delivery?
- 2017
-
In: Journal of Controlled Release. - : ELSEVIER SCIENCE BV. - 0168-3659 .- 1873-4995. ; 246, s. 174-182
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Journal article (peer-reviewed)abstract
- More and more investigations confirm that nanoparticles are incapable of overcoming the intact skin barrier in vivo. Do nanoparticles still have a future in dermal drug delivery? Unlike many other topically applied substances, nanoparticles have not been reported to utilize the intercellular penetration pathway and preferentially make use of the follicular penetration pathway. Deep penetration into the follicular ducts has been described for a variety of particles and appears to be strongly influenced by particle size. For targeted drug delivery, smart nanoparticles are required which are able to release their loaded drugs subsequent to internal or external trigger stimuli, and thereby enable the translocation of the active agents into the viable epidermis. In the recent manuscript, three nanoparticles systems are summarized and compared which release their model drugs upon different trigger mechanisms. The BSA hydrogel nanoparticles release their model drug TRITC-dextran by passive diffusion due to a concentration gradient via a porous surface. The protease-triggered controlled release BSA nanoparticles release their model drug if they are applied simultaneously with protease nanoparticles, resulting in an enzymatic degradation of the particles and a release of the model drug FITC. Finally, the IR-triggered controlled release AuNP-doped BSA nanoparticles release their model drug FITC after photoactivation with wIRA. For all three nanoparticle systems, the release of their model drugs could be observed. For the first nanoparticle system, only low follicular penetration depths were found which might by due do an agglomeration effect. For the last two nanoparticle systems, deep follicular penetration and even an uptake by the sebaceous glands were verified. In conclusion, it could be demonstrated that nanoparticles do have a future in dermal drug delivery if smart nanoparticle systems are utilized which are able to release their drug at specific times and locations within the hair follicle. (C) 2016 Elsevier B.V. All rights reserved.
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| 15. |
- Tran, Ngo Bich Nga Nathalie, et al.
(author)
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Gradient-dependent release of the model drug TRITC-dextran from FITC-labeled BSA hydrogel nanocarriers in the hair follicles of porcine ear skin
- 2017
-
In: European journal of pharmaceutics and biopharmaceutics. - : ELSEVIER SCIENCE BV. - 0939-6411 .- 1873-3441. ; 116, s. 12-16
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Journal article (peer-reviewed)abstract
- Hair follicle research is currently focused on the development of drug-loaded nanocarriers for the targeting of follicular structures in the treatment of skin and hair follicle-related disorders. In the present study, a dual-label nanocarrier system was implemented in which FITC-labeled BSA hydrogel nanocarriers loaded with the model drug and dye TRITC-dextran were applied topically to porcine ear skin. Follicular penetration and the distribution of both dyes corresponding to the nanocarriers and the model drug in the follicular ducts subsequent to administration to the skin were investigated using confocal laser scanning microscopy. The release of TRITC-dextran from the particles was induced by washing of the nanocarriers, which were kept in a buffer containing TRITC-labeled dextran to balance out the diffusion of the dextran during storage, thereby changing the concentration gradient. The results showed a slightly but statistically significantly deeper follicular penetration of fluorescent signals corresponding to TRITC-dextran as opposed to fluorescence corresponding to the FITC-labeled particles. The different localizations of the dyes in the cross-sections of the skin samples evidenced the release of the model drug from the labeled nanoparticles. (C) 2016 Elsevier B.V. All rights reserved.
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| 16. |
- Wen, Xiaogang, et al.
(author)
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Dendritic nanostructures of silver : Facile synthesis, structural characterizations, and sensing applications
- 2006
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In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 22:10, s. 4836-4842
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Journal article (peer-reviewed)abstract
- Silver nanodendrites are synthesized by a simple surfactant-free method using a suspension of zinc microparticles as a heterogeneous reducing agent. Structural characterizations suggest the preferential growth along <100> and <111> directions by oriented attachment of silver nanocrystals in the diffusion limit, leading to the formation of silver nanodendrites 20−30 nm in stem and branch diameter and 5−50 μm in length. Surface-enhanced Raman scattering studies show that the silver nanodentrites give an intensive and enhanced Raman scattering when pyridine was used as a probing molecule. We have also demonstrated that the silver nanodendrites increase the sensitivity of an electrochemical glucose biosensor by as much as 1−2 orders of magnitude.
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| 17. |
- Wing Cheung, Mak, et al.
(author)
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Influence of Different Polyelectrolytes on Layer-by-Layer Microcapsule Properties : Encapsulation Efficiency and Colloidal and Temperature Stability
- 2008
-
In: Chemistry of Materials. - : American Chemical Society (ACS). - 0897-4756 .- 1520-5002. ; 20:17, s. 5475-5484
-
Journal article (peer-reviewed)abstract
- The fabrication of colloidal and temperature stable microcapsules for encapsulation of biomolecules based on matrix-assisted layer-by-layer (LbL) encapsulation by polyelectrolyte self-assembly has been demonstrated. In brief, the process is based on the emulsification of a hydrogel in warm oil for microdroplet formation. The hydrogel acts as a matrix for the later encapsulation process and can be loaded with biomolecules. After microdroplets of, for example, protein loaded hydrogel are formed by emulsification, cooling leads to solidification of the droplets to form microbeads, followed by encapsulation of the hydrogel microbeads with polyelectrolyte multilayers through an LbL self-assembly process to form polymeric capsules. Colloidal stability, encapsulation efficiency, and temperature stability of the LbL hydrogel microcapsules composed from different polyelectrolytes with various ionic strengths and charge densities have been studied. Microcapsules fabricated with strong polyelectrolytes showed better colloidal stability, while microcapsules fabricated with weak polyelectrolytes showed better encapsulation efficiency and temperature stability. After temperature treatment, microcapsules fabricated with different polyelectrolytes exhibited different morphological changes from complete rupturing over broken microcapsules with deformed hollow shells to intact microcapsules. Among all the studied polyelectrolyte pairs, the PAH/PSS polyelectrolyte system was found to be the best material to fabricate microcapsules with good colloidal and temperature stability and high encapsulation efficiency. Microcapsules with PSS as the outermost layer remained similar in size after temperature treatment, while microcapsules with PAH as the outermost layer shrunk by 76% in capsule volume. The present study provides a detailed overview on properties and design of LbL microcapsules as a function of polyelectrolyte materials and layer number. As a result of the versatility of loading LbL hydrogel microcapsules with various biomolecules or mixtures, potential applications are in the fields of diagnostics, drug delivery, and life sciences.
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| 18. |
- Anwar Zainuddin, Ahmad, et al.
(author)
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Modeling of a Novel Biosensor with Integrated Mass and Electrochemical Sensing Capabilities
- 2016
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In: 2016 IEEE EMBS CONFERENCE ON BIOMEDICAL ENGINEERING AND SCIENCES (IECBES). - : IEEE. - 9781467377911 ; , s. 420-425
-
Conference paper (peer-reviewed)abstract
- Rapid development in technology and society has generated diverse developments in many fields including biosensors in healthcare application. Here, the design of integrated biosensor comprises mass sensing (Quartz Crystal Microbalance) and electrochemistry sensing (Electrochemical Impedance Spectroscopy, EIS and Cyclic Voltammetry, CV) will be presented. The integrated sensor system is developed based on the innovative use of the top electrode of a quartz crystal microbalance (QCM) resonator as a working electrode for the electrochemistry technique. Integration of QCM with the electrochemistry technique is realized by fabricating a semicircular counter electrode near the upper electrode on the same side of the quartz crystal. CV and EIS measurement was conducted using finite element modeling, COMSOL (TM) 5.2 with the probe marker of 1 mmol L-1 of [Fe(CN)(6)](3-/4-). CV test was done to study the effect between increasing scan rate and peak current (anodic and cathodic) in observing the reversible electrochemical process. This observation is crucial in ensuring the electrochemical processes follow the Randles-Sevcik equation in characterizing the platform changes behavior. Later, EIS test was performed in order to measure the radius of the semicircle which reflects the charge transfer resistance (R-CT) of the redox marker. To show the effectiveness of this sensor, gold immobilization surface was electrochemically simulated and reported. Thus, an ultra-sensitive biosensor that capable to produce multi-analysis in the detection of biological targets in terms of electrochemical change of electrode interfaces, which is the crucial step towards the engineering of advanced bioelectronics.
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| 19. |
- Asri, Mohd Afiq Mohd, et al.
(author)
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Low-cost and rapid prototyping of integrated electrochemical microfluidic platforms using consumer-grade off-the-shelf tools and materials
- 2022
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In: Lab on a Chip. - : ROYAL SOC CHEMISTRY. - 1473-0197 .- 1473-0189. ; 22:9, s. 1779-1792
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Journal article (peer-reviewed)abstract
- We present a low-cost, accessible, and rapid fabrication process for electrochemical microfluidic sensors. This work leverages the accessibility of consumer-grade electronic craft cutters as the primary tool for patterning of sensor electrodes and microfluidic circuits, while commodity materials such as gold leaf, silver ink pen, double-sided tape, plastic transparency films, and fabric adhesives are used as its base structural materials. The device consists of three layers, the silver reference electrode layer at the top, the PET fluidic circuits in the middle and the gold sensing electrodes at the bottom. Separation of the silver reference electrode from the gold sensing electrodes reduces the possibility of cross-contamination during surface modification. A novel approach in mesoscale patterning of gold leaf electrodes can produce generic designs with dimensions as small as 250 mu m. Silver electrodes with dimensions as small as 385 mu m were drawn using a plotter and a silver ink pen, and fluid microchannels as small as 300 mu m were fabricated using a sandwich of iron-on adhesives and PET. Device layers are then fused together using an office laminator. The integrated microfluidic electrochemical platform has electrode kinetics/performance of Delta E-p = 91.3 mV, I-pa/I-pc = 0.905, characterized by cyclic voltammetry using a standard ferrocyanide redox probe, and this was compared against a commercial screen-printed gold electrode (Delta E-p = 68.9 mV, I-pa/I-pc = 0.984). To validate the performance of the integrated microfluidic electrochemical platform, a catalytic hydrogen peroxide sensor and enzyme-coupled glucose biosensors were developed as demonstrators. Hydrogen peroxide quantitation achieves a limit of detection of 0.713 mM and sensitivity of 78.37 mu A mM(-1) cm(-2), while glucose has a limit of detection of 0.111 mM and sensitivity of 12.68 mu A mM(-1) cm(-2). This rapid process allows an iterative design-build-test cycle in under 2 hours. The upfront cost to set up the system is less than USD 520, with each device costing less than USD 0.12, making this manufacturing process suitable for low-resource laboratories or classroom settings.
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| 20. |
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| 21. |
- Azzouzi, Sawsen, et al.
(author)
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An integrated dual functional recognition/amplification bio-label for the one-step impedimetric detection of Micro-RNA-21
- 2017
-
In: Biosensors & bioelectronics. - : ELSEVIER ADVANCED TECHNOLOGY. - 0956-5663 .- 1873-4235. ; 92, s. 154-161
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Journal article (peer-reviewed)abstract
- Alteration in expression of miRNAs has been correlated with different cancer types, tumour stage and response to treatments. In this context, a structurally responsive oligonucleotide-based electrochemical impedimetric biosensor has been developed for the simple and sensitive detection of miRNA-21. A highly specific biotinylated DNA/LNA molecular beacon (MB) probe was conjugated with gold nanoparticles (AuNPs) to create an integrated, dual function bio-label (biotin-MB-AuNPs) for both biorecognition and signal generation. In the presence of target miRNA-21, hybridisation takes place resulting in the "activation" of the biotin-MB; this event makes the biotin group, which was previously "protected" by the steric hindrance of the MB stem-loop structure, accessible. The activated biotin-MB-AuNPs/miRNA complexes become available for capture, via supramolecular interaction, onto a nentravidin-modified electrode for electrochemical transduction. The binding event results in a decrease of the charge transfer resistance at the working electrode/electrolyte interface. The biosensor responded linearly in the range 1-1000 pM of miRNA-21, with a limit of detection of 0.3 pM, good reproducibility (Relative Standard deviation (RSD) =3.3%) and high selectivity over other miRNAs (i.e. miRNA221 and miRNA-205) sequences. Detection of miRNA-21 in spiked serum samples at clinically relevant levels (low pM range) was also demonstrated, thus illustrating the potential of the biosensor for point-of-care clinical applications. The proposed biosensor design, based on the combination of a neutravidin transducing surface and the dual-function biotin-MB-AuNPs bio-label, provides a simple and robust approach for detection of short-length nucleic acid targets, such as miRNAs.
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| 22. |
- Azzouzi, Sawsen, et al.
(author)
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Generic Neutravidin Biosensor for Simultaneous Multiplex Detection of MicroRNAs via Electrochemically Encoded Responsive Nanolabels
- 2019
-
In: ACS Sensors. - : AMER CHEMICAL SOC. - 2379-3694. ; 4:2, s. 326-334
-
Journal article (peer-reviewed)abstract
- Current electrochemical biosensors for multiple miRNAs require tedious immobilization of various nucleic acid probes. Here, we demonstrate an innovative approach using a generic neutravidin biosensor combined with electrochemically encoded responsive nanolabels for facile and simultaneous multiplexed detection of miRNA-21 and miRNA-141. The selectivity of the biosensor arises from the intrinsic properties of the electrochemically encoded responsive nanolabels, comprising biotinylated molecular beacons (biotin-MB) and metal nanoparticles (metal-NPs). The procedure is a simple one-pot assay, where the targeted miRNA causes the opening of biotin-MB followed by capturing of the biotin-MB-metal-NPs by the neutravidin biosensor and simultaneous detection of the captured metal-NPs by stripping square-wave voltammetry (SSWV). The multiplexed detection of miRNA-21 and miRNA-141 is achieved by differentiation of the electrochemical signature (i.e., the peak current) for the different metal-NP labels. The biosensor delivers simultaneous detection of miRNAs with a linear range of 0.5-1000 pM for miRNA-21 and a limit of detection of 0.3 pM (3 sigma/sensitivity, n = 3), and a range of 50-1000 pM for miRNA-141, with a limit of detection of 10 pM. Furthermore, we demonstrate multiplexed detection of miRNA-21 and miRNA-141 in a spiked serum sample.
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| 23. |
- Bai, Jianhao, et al.
(author)
-
Fabrication of inflated LbL microcapsules with a ‘bead-in-a-capsule’ morphology
- 2009
-
In: Soft Matter. - : Royal Society of Chemistry. - 1744-683X .- 1744-6848. ; 5, s. 4152-4160
-
Journal article (peer-reviewed)abstract
- The fabrication of inflated Layer-by-Layer (LbL) microcapsules with a unique ‘bead-in-a-capsule’ morphology is presented. Currently, the fabrication of LbL microcapsules using conventional aqueous LbL techniques usually results in microcapsules with a two-phase system (LbL capsular wall with an air, liquid, solid or hydrogel core). Here, we present the fabrication of inflated LbL microcapsules with a unique three-phase system (LbL capsular wall, hydrogel microbead in an aqueous core) by using the Reverse-Phase LbL (RP-LbL) technique. The RP-LbL technique is performed in an organic solvent and allows encapsulation of water-soluble templates and molecules with high efficiency. Firstly, the RP-LbL technique is used to coat polymer layers onto agarose microbeads containing TRIS buffer for the formation of LbL capsular walls onto the microbeads and to minimize out-diffusion of encapsulated TRIS. Next, the polymer-coated agarose microbeads are transferred from an organic to an aqueous solvent where the TRIS molecules induce an osmotic pressure in the microcapsules' interior. This pressure drives the inflation of the LbL microcapsules that causes the expansion of the LbL capsular walls. Fluorescence staining reveals that the inflated LbL microcapsules consist of an agarose microbead suspended within the aqueous interior of the capsule but still attached to the LbL capsular wall at one point; thereby displaying a ‘bead-in-a-capsule’ morphology. It was demonstrated that the degree of inflation depends on the concentration of pre-loaded TRIS and the number of coated polymer layers. Also, ADOGEN® 464 (a cationic surfactant) is required for the fabrication of the inflated LbL microcapsules. The mass of dextran macromolecules (65–2000 kDa) diffusing through the LbL capsular wall had decreased by at least 49% after expansion of the capsular wall. Inflated microcapsules were shown to be capable of controlling the distribution of two different materials internally. Hence, it is possible that inflated microcapsules can permit localized control over chemical or enzymatic reactions for future uses in biomedical applications.
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| 24. |
- Beyer, Sebastian, et al.
(author)
-
Reverse-phase LbL-encapsulation of highly water soluble materials by layer-by-layer polyelectrolyte self-assembly
- 2007
-
In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 23:17, s. 8827-8832
-
Journal article (peer-reviewed)abstract
- We report on a novel method for the encapsulation of highly water soluble materials by using layer-by-layer (LbL) polyelectrolyte self-assembly. State of the art polyelectrolyte self-assembly LbL coating and encapsulation methods are only applicable to insoluble or poorly water soluble template materials, because the process is performed in water causing dissolution of the solid template. Our method extends the material spectrum to highly water soluble template materials by using non-ionized polyelectrolytes in an organic phase (reverse-phase) instead of polyelectrolyte salts in an aqueous environment. By using the reverse-phase layer-by-layer (RP-LbL) technique, we have demonstrated the direct encapsulation of proteins, glucose, vitamin C, and inorganic salts in the solid state. Multilayer deposition was proven, layer thickness was determined by AFM, and the advantage of the method to prepare powders of encapsulated materials was demonstrated. The method is simple, robust, and applicable to a broad range of substances with potential applications in several industries.
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| 25. |
- Changsan, Titiwan, et al.
(author)
-
Magnetic microsphere sorbent on CaCO3 templates: Simple synthesis and efficient extraction of trace carbamate pesticides in fresh produce
- 2021
-
In: Food Chemistry. - : Elsevier Applied Science Publishers. - 0308-8146 .- 1873-7072. ; 342
-
Journal article (peer-reviewed)abstract
- Polypyrrole magnetic microspheres were synthesized and used to extract carbaryl, carbofuran, and methomyl before analysis by a high-performance liquid chromatography with diode array detection. Under optimal conditions, four times the preconcentration was achieved with the use of only 1.2 mL of sample. Good linearity with ranges of 3.0–7.5 × 103, 6.0–4.5 × 103, and 15–3.0 × 103 ng kg−1 and limits of detection of 1.37 ± 0.10, 4.7 ± 1.2, and 10.1 ± 5.7 ng kg−1 were obtained, respectively. Good reproducibility (RSDs < 5%) was achieved over 24 cycles of extraction and regeneration. Good accuracy (recoveries 81.6 ± 1.5%–108.3 ± 2.2%) and good precision (RSDs 0.11%–4.5%) were obtained. Carbaryl was detected in apple (2.75 ± 0.23 ng kg−1), carbofuran in tomato (11.34 ± 0.61 ng kg−1), and methomyl in watermelon (34.7 ± 1.7 ng kg−1). The relative expanded uncertainty of the measurement method was less than 14% for all three pesticides.
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| 26. |
- Che, Canyan, 1988-, et al.
(author)
-
Twinning Lignosulfonate with a Conducting Polymer via Counter-Ion Exchange for Large-Scale Electrical Storage
- 2019
-
In: Advanced Sustainable Systems. - : Wiley-VCH Verlag. - 2366-7486. ; 3:9
-
Journal article (peer-reviewed)abstract
- Lignosulfonate (LS) is a large-scale surplus product of the forest and paper industries, and has primarily been utilized as a low-cost plasticizer in making concrete for the construction industry. LS is an anionic redox-active polyelectrolyte and is a promising candidate to boost the charge capacity of the positive electrode (positrode) in redox-supercapacitors. Here, the physical-chemical investigation of how this biopolymer incorporates into the conducting polymer PEDOT matrix, of the positrode, by means of counter-ion exchange is reported. Upon successful incorporation, an optimal access to redox moieties is achieved, which provides a 63% increase of the resulting stored electrical charge by reversible redox interconversion. The effects of pH, ionic strength, and concentrations, of included components, on the polymer–polymer interactions are optimized to exploit the biopolymer-associated redox currents. Further, the explored LS-conducting polymer incorporation strategy, via aqueous synthesis, is evaluated in an up-scaling effort toward large-scale electrical energy storage technology. By using an up-scaled production protocol, integration of the biopolymer within the conducting polymer matrix by counter-ion exchange is confirmed and the PEDOT-LS synthesized through optimized strategy reaches an improved charge capacity of 44.6 mAh g−1.
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| 27. |
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| 28. |
- Fredj, Zina, et al.
(author)
-
Neutravidin biosensor for direct capture of dual-functional biotin-molecular beacon-AuNP probe for sensitive voltammetric detection of microRNA
- 2017
-
In: Sensors and actuators. B, Chemical. - : Elsevier. - 0925-4005 .- 1873-3077. ; 248, s. 77-84
-
Journal article (peer-reviewed)abstract
- We have demonstrated a new approach using a neutravidin-based biosensor combined with a dual-function gold nanoparticle (AuNP) biolabel, for simple and sensitive detection of microRNA-21 (miRNA-21). The selectivity of the biosensor is provided by the intrinsic properties of the dual-functional biotin-MB-AuNP label. The assay procedure is relatively simple, exploiting a one-pot assay concept where the affinity capture of the miRNA-21/dual-functional biotin-MB-AuNP complex, via the strong biotin-neutravidin supramolecular interaction, and simultaneous detection of the captured AuNPs label with stripping voltammetry, is performed in a single step. This electrochemical miRNA biosensor could detect miRNA-21 with limit of detection of 0.1×10less thansuperscriptgreater than−12less than/superscriptgreater than and a dynamic range from 0.5×10less thansuperscriptgreater than−12less than/superscriptgreater than to 1.0×10less thansuperscriptgreater than−9less than/superscriptgreater thanM. The performance of the miRNA-21biosensor was further improved after silver deposition onto the AuNPs, delivering an enhanced detection limit of 4.0×10less thansuperscriptgreater than−15less than/superscriptgreater thanM of miRNA-21, and an extremely wide analytic dynamic range from 10×10less thansuperscriptgreater than−15less than/superscriptgreater than to 1×10less thansuperscriptgreater than−9less than/superscriptgreater thanM (5 orders of magnitude). This exceptionally broad dynamic range demonstrates the advantage of the one-pot assay approach with direct capture of the dual functional biotin-MB-AuNP via the strong biotin-neutravidin supramolecular interaction. Furthermore, we demonstrated the detection of miRNA-21 in spiked serum at clinically relevant concentrations. The miRNA biosensor displayed excellent analytical performance for the detection of miRNA and could provide a powerful and convenient tool for biomedical research and applications in cancer diagnostics.
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| 29. |
- Hatamie, Amir, et al.
(author)
-
Zinc Oxide Nanostructure-Modified Textile and Its Application to Biosensing, Photocatalysis, and as Antibacterial Material
- 2015
-
In: Langmuir. - : AMER CHEMICAL SOC. - 0743-7463 .- 1520-5827. ; 31:39, s. 10913-10921
-
Journal article (peer-reviewed)abstract
- Recently, one-dimensional nanostructures with different morphologies (such as nanowires, nanorods (NRs), and nanotubes) have become the focus of intensive research, because of their unique properties with potential applications. Among them, zinc oxide (ZnO) nanomaterials has been found to be highly attractive, because of the remarkable potential for applications in many different areas such as solar cells, sensors, piezoelectric devices, photodiode devices, sun screens, antireflection coatings, and photocatalysis. Here, we present an innovative approach to create a new modified textile by direct in situ growth of vertically aligned one-dimensional (1D) ZnO NRs onto textile surfaces, which can serve with potential for biosensing, photocatalysis, and antibacterial applications. ZnO NRs were grown by using a simple aqueous chemical growth method. Results from analyses such as X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that the ZnO NRs were dispersed over the entire surface of the textile. We have demonstrated the following applications of these multifunctional textiles: (1) as a flexible working electrode for the detection of aldicarb (ALD) pesticide, (2) as a photo catalyst for the degradation of organic molecules (i.e., Methylene Blue and Congo Red), and (3) as antibacterial agents against Escherichia coli. The ZnO-based textile exhibited excellent photocatalytic and antibacterial activities, and it showed a promising sensing response. The combination of sensing, photo catalysis, and antibacterial properties provided by the ZnO NRs brings us closer to the concept of smart textiles for wearable sensing without a deodorant and antibacterial control. Perhaps the best known of the products that is available in markets for such purposes are textiles with silver nanoparticles. Our modified textile is thus providing acceptable antibacterial properties, compared to available commercial modified textiles.
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| 30. |
- Jiang, Jie, et al.
(author)
-
Integrated direct DNA/protein patterning and microfabrication by focused ion beam milling
- 2008
-
In: Advanced Materials. - : John Wiley & Sons. - 0935-9648 .- 1521-4095. ; 20:9, s. 1636-1643
-
Journal article (peer-reviewed)abstract
- Single and binary component patterning and integrated microfabrication of biomolecules, such as DNA and proteins, can be achieved by focused ion-beam (FIB) biolithography. Well-defined micropatterns are obtained by FIB milling on biomolecules immobilized on SiO2 wafers and protected by a thin Au film. The retention of biofunctionality is excellent (68–90%) and a feature size of down to 500 nm can be achieved for the patterns without significant loss of functionality.
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| 31. |
- Jianhao, Bai, et al.
(author)
-
Inwards buildup of concentric polymer layers: A method for biomolecule encapsulation and microcapsule encoding
- 2010
-
In: Angewandte Chemie International Edition. - Weinheim, Germany : Wiley-VCH Verlagsgesellschaft. - 1433-7851 .- 1521-3773. ; 49:330, s. 5189-5193
-
Journal article (peer-reviewed)abstract
- Encoding by encapsulation: A polymeric shell fabrication approach combines biomolecule encapsulation with encoding. Striated polymeric shells, fabricated through an inwards diffusion of poly(allylamine) into the matrices of agarose microbeads, serves to encapsulate the biomolecules within the microcapsule. Encoding is performed through the color and/or thickness permutation of the striated polymeric shells (see picture).
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| 32. |
- Kangkamano, Tawatchai, et al.
(author)
-
Product-to-intermediate relay achieving complete oxygen reduction reaction (cORR) with Prussian blue integrated nanoporous polymer cathode in fuel cells
- 2020
-
In: Nano Energy. - : ELSEVIER. - 2211-2855 .- 2211-3282. ; 78
-
Journal article (peer-reviewed)abstract
- The oxygen reduction reaction (ORR) is an essential process in electrocatalysis limiting the commercialization of sustainable energy conversion technologies, such as fuel cells. The use of conducting polymers as molecular porous and conducting catalysts obtained from the high abundance elements enables the route towards low cost and high-throughput fabrication of disposable plastic electrodes of fuel cells. Poly(3,4-ethylenedioxythiophene) (PEDOT) is a 2-electron ORR electrocatalyst yielding specifically hydrogen peroxide that limits the full utilization of chemical energy of oxygen. Here, we demonstrated an innovative product-to-intermediate relay approach achieving complete oxygen reduction reaction (cORR) with Prussian blue (PB) integrated microporous PEDOT cathode in fuel cells. The microporous structured PEDOT electrode prepared via a simple cryosynthesis allows the bulk integration and stabilization of the poor conducting PB co-catalyst into the PEDOT ion-electron conductor, while the microporous PEDOT allows effective oxygen diffusion into the matrix. We evaluated systematically the effect of sequential PEDOT 2-electron ORR followed by PB co-catalysis launching hydrogen peroxide reduction reaction (HPRR) into H2O. This resulted in the establishment of electronic and ionic transport between PEDOT and PB catalyst enabling the combination of enhanced ORR electrocatalysis by means of the ORR course extension from 2to 4-electron reduction to achieve cORR. The cORR performance delivered by the product-to-intermediate relay between microporous PEDOT and PB co-catalysis led to a four times increase in power density of model proton-exchange membrane fuel cell (PEMFC) assembled from the polymer-based air breathing cathode.
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| 33. |
- Kei Lai, Kwok, et al.
(author)
-
Bioinspired protein microparticles fabrication by peptide mediated disulfide interchange
- 2014
-
In: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 4:23, s. 11802-11810
-
Journal article (peer-reviewed)abstract
- In this article, we report an innovative green chemistry approach for the fabrication of protein microparticles based on peptide mediated disulfide interchange reactions. The concept is based on using a redox reactive peptide, glutathione, as a natural crosslink reagent triggering the formation of intermolecular disulfide bonds between adjacent protein molecules leading to the assembly of protein molecules within a CaCO3 template into a microparticle structure. The CaCO3 template is highly biocompatible and is completely removed by simply adjusting the solution to pH 5.0, leaving behind the pure protein microparticles. Moreover, the GSH is only involved in the intermediate step without being incorporated into the resulting protein microparticles, therefore producing protein microparticles composed of purely protein molecules. This technology provides a simple and robust method to fabricate protein microparticles under physiological aqueous conditions, and more importantly avoiding the extensive use of synthetic chemical crosslinking reagents. We have further demonstrated that this method is versatile to fabricate microparticles with various proteins such as BSA, enzymes and antibodies. The biological functions such as catalytic properties and affinity interactions of the resulting protein microparticles are highly conserved which demonstrate the potential applications of the protein microparticles in the area of biocatalysis, bioseparation and targeted drug delivery.
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| 34. |
- Kongkaew, Supatinee, et al.
(author)
-
Craft-and-Stick Xurographic Manufacturing of Integrated Microfluidic Electrochemical Sensing Platform
- 2023
-
In: Biosensors. - : MDPI. - 2079-6374. ; 13:4
-
Journal article (peer-reviewed)abstract
- An innovative modular approach for facile design and construction of flexible microfluidic biosensor platforms based on a dry manufacturing "craft-and-stick" approach is developed. The design and fabrication of the flexible graphene paper electrode (GPE) unit and polyethylene tetraphthalate sheet (PET)6/adhesive fluidic unit are completed by an economic and generic xurographic craft approach. The GPE widths and the microfluidic channels can be constructed down to 300 mu m and 200 mu m, respectively. Both units were assembled by simple double-sided adhesive tapes into a microfluidic integrated GPE (MF-iGPE) that are flexible, thin (<0.5 mm), and lightweight (0.4 g). We further functionalized the iGPE with Prussian blue and glucose oxidase for the fabrication of MF-iGPE glucose biosensors. With a closed-channel PET fluidic pattern, the MF-iGPE glucose biosensors were packaged and sealed to protect the integrated device from moisture for storage and could easily open with scissors for sample loading. Our glucose biosensors showed 2 linear dynamic regions of 0.05-1.0 and 1.0-5.5 mmol L-1 glucose. The MF-iGPE showed good reproducibility for glucose detection (RSD < 6.1%, n = 6) and required only 10 mu L of the analyte. This modular craft-and-stick manufacturing approach could potentially further develop along the concept of paper-crafted model assembly kits suitable for low-resource laboratories or classroom settings.
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| 35. |
- Kongkaew, Supatinee, et al.
(author)
-
Evaluation on the Intrinsic Physicoelectrochemical Attributes and Engineering of Micro-, Nano-, and 2D-Structured Allotropic Carbon-Based Papers for Flexible Electronics
- 2021
-
In: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 37:49, s. 14302-14313
-
Journal article (peer-reviewed)abstract
- Flexible electronics have gained more attention for emerging electronic devices such as sensors, biosensors, and batteries with advantageous properties including being thin, lightweight, flexible, and low-cost. The development of various forms of allotropic carbon papers provided a new dry-manufacturing route for the fabrication of flexible and wearable electronics, while the electrochemical performance and the bending stability are largely influenced by the bulk morphology and the micro-/nanostructured domains of the carbon papers. Here, we evaluate systematically the intrinsic physicoelectrochemical properties of allotropic carbon-based conducting papers as flexible electrodes including carbon-nanotubes-paper (CNTs-paper), graphene-paper (GR-paper), and carbon-fiber-paper (CF-paper), followed by functionalization of the allotropic carbon papers for the fabrication of flexible electrodes. The morphology, chemical structure, and defects originating from the allotropic nanostructured carbon materials were characterized by scanning electron microscopy (SEM) and Raman spectroscopy, followed by evaluating the electrochemical performance of the corresponding flexible electrodes by cyclic voltammetry and electrochemical impedance spectroscopy. The electron-transfer rate constants of the CNTs-paper and GR-paper electrodes were similar to 14 times higher compared with the CF-paper electrode. The CNTs-paper and GR-paper electrodes composed of nanostructured carbon showed significantly higher bending stabilities of 5.61 and 4.96 times compared with the CF-paper. The carbon-paper flexible electrodes were further functionalized with an inorganic catalyst, Prussian blue (PB), forming the PB-carbon-paper catalytic electrode and an organic conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), forming the PEDOT-carbon-paper capacitive electrode. The intrinsic attribute of different allotropic carbon electrodes affects the deposition of PB and PEDOT, leading to different electrocatalytic and capacitive performances. These findings are insightful for the future development and fabrication of advanced flexible electronics with allotropic carbon papers.
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| 36. |
- Kor, Kamalodin, et al.
(author)
-
Structurally responsive oligonucleotide-based single-probe lateral-flow test for detection of miRNA-21 mimics
- 2016
-
In: Analytical and Bioanalytical Chemistry. - : Springer Berlin/Heidelberg. - 1618-2642 .- 1618-2650. ; 408:5, s. 1475-1485
-
Journal article (peer-reviewed)abstract
- A single-probe strip test for the rapid and sensitive detection of miRNA-21 mimics is reported herein. Highly specific structurally responsive bi-functional, thiol and biotin, DNA/LNA oligonucleotide probes (molecular beacons-MB) were designed and conjugated with gold nanoparticles (AuNPs) (i.e. biotin-MB-AuNPs). The proposed design had the ability to modulate the accessibility of the biotin group as a function of the presence of a miRNA target allowing the interaction of the boilable with the streptavidin test zone only in the presence of the miRNA-21 mimics. For quantitative evaluation, images of the strip tests were recorded using a flatbed scanner (Epson Perfection V370 Photo). The colour intensities of the test zones of the strip tests were analysed with the ImageJ software (Scion Corp., USA) and quantified as a function of pixel intensity. The response of the strip test was linear over the range 0.5 to 20 nM miRNA-21 (limit of detection of 115 pM) and showed good reproducibility (intra and inter CVs below 8 %); furthermore, the assay was shown to be highly selective, discriminating other interference miRNAs mimics (e.g. miRNA-221 and miRNA-205). Finally, the proposed strip test was used for detection of miRNA-21 mimics in spiked serum samples, demonstrating its potential for point-of-care clinical applications. Main advantages of the single-probe strip test design are its versatility, simplicity and robustness, which can be easily extended to other miRNA targets by tuning the sequence of the single probe. Furthermore, the use of the structurally responsive single probe is particularly relevant in the case of short-length targets, such as miRNA, whereas a conventional sandwich approach might require a careful control of assay conditions such as hybridization temperature and salt concentration
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| 37. |
- Kwok Kei, Lai, et al.
(author)
-
Multifunctional protein particles with dual analytical channels for colorimetric enzymatic bioassays and fluorescent immunoassays
- 2012
-
In: Biosensors & bioelectronics. - : Elsevier BV. - 0956-5663 .- 1873-4235. ; 32:1, s. 169-176
-
Journal article (peer-reviewed)abstract
- Advanced multifunctional protein particles encapsulated enzymes and antibodies were developed for enzymatic bioassays and immunoassays with colorimetric and fluorescent channels. A colorimetric channel based on color-substrate precipitation was assigned for enzymatic bioassays for the measurement of hydrogen peroxide with the lowest detectable concentration of 10 μM. A fluorescent channel based on fluorescent labeled antibodies was assigned for immunoassays for the measurement of mouse immunoglobulin G (M IgG) with the lowest detectable concentration of 1.25 μg L−1. The protein microparticles were fabricated with a template-assisted self-assembly technique termed “Protein Activation Spontaneous Self-assemble” (PASS). The multifunctional protein particles prepared with the PASS method have the advantages of high loading of analytical biomolecules, integrated biological functions, porous structure, and more importantly, they are optically transparent and fluorescence inactive. These unique features make our protein particles a new generation of bead-based platforms to perform enzyme bioassays and immunoassays.
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| 38. |
- Lademann, Jürgen, et al.
(author)
-
Drug delivery with topically applied nanoparticles : science fiction or reality
- 2013
-
In: Skin Pharmacology and Physiology. - : S. Karger. - 1660-5527 .- 1660-5535. ; 26:4-6, s. 227-233
-
Journal article (peer-reviewed)abstract
- The efficacy of topically applied drugs is determined by their action mechanism and their potential capacity of passing the skin barrier. Nanoparticles are assumed to be efficient carrier systems for drug delivery through the skin barrier. For flexible nanoparticles like liposomes, this effect has been well demonstrated. The penetration properties of solid nanoparticles are currently under intensive investigation. The crucial advantage of nanoparticles over non-particulate substances is their capability to penetrate deeply into the hair follicles where they can be stored for several days. There is no evidence, yet, that solid particles ≥40 nm are capable of passing through the healthy skin barrier. Therefore and in spite of the long-standing research efforts in this field, commercially available solid nanoparticle-based products for drug delivery through the healthy skin are still missing. Nevertheless, the prospects for the clinical use of nanoparticles in drug delivery are tremendous. They can be designed as transport systems delivering drugs efficiently into the hair follicles in the vicinity of specific target structures. Once deposited at these structures, specific signals might trigger the release of the drugs and exert their effects on the target cells. In this article, examples of such triggered drug release are presented.
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| 39. |
- Lai, Kwok Kei, et al.
(author)
-
High efficiency single-step biomaterial-based microparticle fabrication via template-directed supramolecular coordination chemistry
- 2016
-
In: Green Chemistry. - : Royal Society of Chemistry (RSC). - 1463-9262 .- 1463-9270. ; 18:6, s. 1715-1723
-
Journal article (peer-reviewed)abstract
- Biomaterial-based microparticles have attracted much attention for medical and biological applications such as pharmaceutics, bioseparation and cosmetics. Emerging technologies enable versatile and facile fabrication of microparticles, with key features being purity, precise size control, mild preparation conditions and minimal processing. Here, an innovative approach combining template synthesis, biomolecule assembly and partial-purification within a single step for high efficiency fabrication of pure biomaterial-based microparticles is reported. This concept is based on facile co-precipitation of biomolecules within CaCO3 templates and simultaneous crosslinking of entrapped biomolecules via Ca2+ driven supramolecular coordination chemistry, followed by template removal. Carbohydrate (alginate) and proteins (casein and fresh milk) are used as models of biomolecules. The process driven by selective crosslinking automatically excludes non-specific materials from the template and thus provides the additional function of partial-purification, as demonstrated using highly complexed fresh milk. This green approach to fabrication of biomaterial-based microparticles offers three critical advantages (i) mild conditions to preserve the chemical and secondary structures of biomolecules; (ii) single processing step to facilitate scale-up production; and (iii) partial-purification without the need for upstream raw material purification. This innovative approach not only addresses fundamental issues in fabrication techniques, but also marks progress in energy and environmental conservation during manufacturing processes.
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| 40. |
- Liu, Yu, et al.
(author)
-
Facile synthesis of highly processable and water dispersible polypyrrole and poly(3,4-ethylenedioxythiophene) microspheres for enhanced supercapacitive performance
- 2018
-
In: European Polymer Journal. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0014-3057 .- 1873-1945. ; 99, s. 332-339
-
Journal article (peer-reviewed)abstract
- Much recent work has focused on improving the processibility and electrocapacitive performance of conducting polymer-based materials for energy related applications. The key mechanism of conducting polymers as supercapacitor materials is driven by the rapid charging and discharging processes that involve mass transport of the counter ions insertion/ejection within the polymer structure, where ion diffusion is usually the limiting step on the efficiency of the conducting polymer capacitor. Here, we report a facile method for the green fabrication of polypyrrole microspheres (PPy-MSs) and poly (3, 4-ethylenedioxythiophene) microspheres (PEDOT-MSs) with good processability, intact morphology and large active surface for enhanced ion interchange processes, without using surfactant and highly irritant or toxic organic solvents during the synthetic process. The structure and morphology of the PPy-MSs and PEDOT-MSs were characterized by means of SEM, EDX, TEM and FTIR. Both PPy-MSs and PEDOT-MSs showed intact microsphere structures with greatly improved water dispersity and processability. More importantly, facilated by the large active surface and inter-microsphere space for ions diffusion, both the PPy-MSs and PEDOT-MSs showed a signiciantly enhanced electrical capacitive performance of 242 F g(-1) and 91.2 F g(-1), repsectively (i.e. 10 and 1.51 times in specific capacitance than the randomly structured PPy and PEDOT). This innovative approach not only addresses fundamental issues in fabrication of high performance processable microstructured conducting polymers, but also makes progress in delivering water processable conducting polymers that could be potentially used for fabrication of printed electronic devices.
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| 41. |
- Liu, Yu, et al.
(author)
-
Processable enzyme-hybrid conductive polymer composites for electrochemical biosensing
- 2018
-
In: Biosensors & bioelectronics. - : ELSEVIER ADVANCED TECHNOLOGY. - 0956-5663 .- 1873-4235. ; 100, s. 374-381
-
Journal article (peer-reviewed)abstract
- A new approach for the facile fabrication of electrochemical biosensors using a biohybrid conducting polymer was demonstrated using glucose oxidase (GOx) and poly (3, 4-ethylenedioxythiophene) (PEDOT) as a model. The biohybrid conducting polymer was prepared based on a template-assisted chemical polymerisation leading to the formation of PEDOT microspheres (PEDOT-MSs), followed by in-situ deposition of platinum nanoparticles (PtNPs) and electrostatic immobilisation of glucose oxidase (GOx) to form water processable GOx-PtNPs-PEDOT-MSs. The morphology, chemical composition and electrochemical performance of the GOx-PtNPs-PEDOT-MS-based glucose biosensor were characterised using scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), Fourier transform infrared (FTIR) spectroscopy, zeta potential and electrochemical measurements, respectively. The biosensor delivered a linear response for glucose over the range 0.1-10 mM (R-2 = 0.9855) with a sensitivity of 116.25 mu A mM(-1) cm(-2), and limit of detection of 1.55 mu M (3 x SD/sensitivity). The sensitivity of the developed PEDOT-MS based biosensor is significantly higher (2.7 times) than the best reported PEDOT-based glucose biosensor in the literature. The apparent Michaelis Menten constant (K-m(app)) of the GOx-PtNPs-PEDOT-MS-based biosensors was calculated as 7.3 mM. Moreover, the biosensor exhibited good storage stability, retaining 97% of its sensitivity after 12 days storage. This new bio-hybrid conducting polymer combines the advantages of micro-structured morphology, compatibility with large-scale manufacturing processes, and intrinsic biocatalytic activity and conductivity, thus demonstrating its potential as a convenient material for printed bioelectronics and sensors.
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| 42. |
- Loo, Jacky F. C., et al.
(author)
-
Integrated Printed Microfluidic Biosensors
- 2019
-
In: Trends in Biotechnology. - : ELSEVIER SCIENCE LONDON. - 0167-7799 .- 1879-3096. ; 37:10, s. 1104-1120
-
Research review (peer-reviewed)abstract
- Integrated printed microfluidic biosensors are one of the most recent point-of-care (POC) sensor developments. Fast turnaround time for production and ease of customization, enabled by the integration of recognition elements and transducers, are key for on-site biosensing for both healthcare and industry and for speeding up translation to real-life applications. Here, we provide an overview of recent progress in printed microfluidics, from the 2D to the 4D level, accompanied by novel sensing element integration. We also explore the latest trends in integrated printed microfluidics for healthcare, especially POC diagnostics, and food safety applications.
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| 43. |
- Mak, Wing Cheung, et al.
(author)
-
Biofunctionalized indigo-nanoparticles as biolabels for the generation of precipitated visible signal in immunodipsticks
- 2011
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In: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 26:7, s. 3148-3153
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Journal article (peer-reviewed)abstract
- A novel class of organic nanoparticles as biolabels that can generate an instant visible signal was applied to immunodipsticks. A new principle for signal generation based on hydrolysis of colourless signal precursor molecules to produce coloured signal molecules followed by signal precipitation and localization was demonstrated. The nanoparticle biolabels were applied to sandwich immunoassays for the detection of mouse immunoglobulin G (M IgG). In the presence of M IgG, a nanoparticle-immunocomplex was formed and bound on the test zone immobilized with goat anti M IgG (Gt α M IgG). A blue line was developed on the test zone upon the addition of a signal developing reagent. An optical signal could be simply assessed using naked eyes or quantified using a reading device. The lowest visible signal that could be observed using naked eyes was found to be 1.25 μg L−1 M IgG. The nanoparticle biolabel also showed a better sensitivity (signal-to-noise ratio) compared with the conventional colloidal gold biolabel. This novel class of organic nanoparticles offers an alternative biolabel system for the development of point-of-care immunodipsticks.
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| 44. |
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| 45. |
- Mak, Wing Cheung, et al.
(author)
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Biosensor for rapid phosphate monitoring in sequencing batch reactor (SBR) system
- 2003
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In: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 19:3, s. 233-237
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Journal article (peer-reviewed)abstract
- A thick-film phosphate biosensor based on hydrogel immobilized pyruvate oxidase (POD) has been developed for rapid phosphate process control monitoring in an experimental sequencing batch reactor (SBR) system. We have employed a phosphate biosensor in an off-line monitoring of phosphate concentrations in a bench scale SBR. Measurements with biosensor show a good correlation (r2=0.98) with those of commercial colorimetric phosphate testing kits. The signal response time was 1 min with a detection limit of 5 microM. The biosensor method showed a good operational stability, needed less experimental procedures and a small sample size (approximately 20 microl). This allows its practical application for rapid phosphate measurements to obtain real time process data in a SBR system.
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| 46. |
- Mak, Wing Cheung, 1977-
(author)
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Biosensor technologies for agriculture and environment - opportunities and challenges
- 2017
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In: Proceedings of the 8th Nordic Feed Science Conference, Uppsala, Sweden, 13-14 June 2017. - Uppsala : Swedish University of Agricultural Sciences, Department of Animal Nutrition and Management. ; , s. 38-41
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Conference paper (peer-reviewed)abstract
- This paper presents the general principles of various biosensor systems, reviews current biosensor technologies for agricultural and environmental monitoring, and discusses their opportunities and challenges. Advances in biosensor technologies could provide a useful analytical tools for agricultural monitoring, particularly due to their rapid response, relatively low operational cost and portability for field/farm application. The promise, demonstrated by various examples of biosensor technologies, is very appealing. However, there are still many hurdles to bring commercial agricultural biosensors into real practice.
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| 47. |
- Mak, Wing Cheung, et al.
(author)
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Controlled Delivery of Human Cells by Temperature Responsive Microcapsules
- 2015
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In: Journal of Functional Biomaterials. - : MDPI. - 2079-4983. ; 6:2, s. 439-453
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Journal article (peer-reviewed)abstract
- Cell therapy is one of the most promising areas within regenerative medicine. However, its full potential is limited by the rapid loss of introduced therapeutic cells before their full effects can be exploited, due in part to anoikis, and in part to the adverse environments often found within the pathologic tissues that the cells have been grafted into. Encapsulation of individual cells has been proposed as a means of increasing cell viability. In this study, we developed a facile, high throughput method for creating temperature responsive microcapsules comprising agarose, gelatin and fibrinogen for delivery and subsequent controlled release of cells. We verified the hypothesis that composite capsules combining agarose and gelatin, which possess different phase transition temperatures from solid to liquid, facilitated the destabilization of the capsules for cell release. Cell encapsulation and controlled release was demonstrated using human fibroblasts as model cells, as well as a therapeutically relevant cell line—human umbilical vein endothelial cells (HUVECs). While such temperature responsive cell microcapsules promise effective, controlled release of potential therapeutic cells at physiological temperatures, further work will be needed to augment the composition of the microcapsules and optimize the numbers of cells per capsule prior to clinical evaluation.
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| 48. |
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| 49. |
- Mak, Wing Cheung, 1977-, et al.
(author)
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Drug delivery into the skin by degradable particles
- 2011
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In: European journal of pharmaceutics and biopharmaceutics. - : Elsevier. - 0939-6411 .- 1873-3441. ; 79:1, s. 23-27
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Journal article (peer-reviewed)abstract
- Recently, it was demonstrated that particles could be utilized as carrier systems for drugs into the hair follicles. In the present study, a two-component drug delivery system is presented consisting of degradable particles loaded with fluorescein isothiocyanate and a separate protease formulation for degradation. The particles were applied alone, 30 min previous to the protease application and simultaneously with the protease onto porcine skin. Subsequently, biopsies were removed, and the penetration depths of the particles were analyzed using laser scanning microscopy.The obtained results demonstrate that the particles alone achieved a penetration depth of around 900 μm. Similar results were obtained for the successive application of particles and protease, whereas a release of the fluorescent dye was only observed in the upper 250 μm corresponding to the penetration depth of the protease. In the case of the simultaneous application, the particles were partly dissolved before application, leading to a reduced particle size and diminished penetration depth.The results revealed that degradable particles are a promising tool for drug delivery into the skin.
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| 50. |
- Mak, Wing Cheung, et al.
(author)
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Lateral-flow technology: from visual to instrumental.
- 2016
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In: TrAC. Trends in analytical chemistry. - : Elsevier. - 0165-9936 .- 1879-3142. ; 79:SI, s. 297-305
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Research review (peer-reviewed)abstract
- Lateral-flow tests were first launched commercially in 1984, as a simple urine-based pregnancy test for home use. The simplicity of the visual readout delivered by the basic lateral-flow format proved to be a very popular. However, the recent apparently unstoppable trend towards portable and wearable technology is driving the lateral-flow strip towards an industrial interface that will enable it to interface with big data and expert systems, and where ready transmission of data is essential. In this review, we chart the inevitable evolution of the visually-read lateral-flow strip to more advanced instrumented versions and consider the future of this very flexible approach to delivering simple affinity assays. We examine recent labelling strategies, the relative merits of optical and electrochemical transducers and explore the evolution of recognition elements that are now being incorporated into these systems.
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