| 1. |
- Che, Canyan, 1988-, et al.
(författare)
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Twinning Lignosulfonate with a Conducting Polymer via Counter-Ion Exchange for Large-Scale Electrical Storage
- 2019
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Ingår i: Advanced Sustainable Systems. - : Wiley-VCH Verlag. - 2366-7486. ; 3:9
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Ghani, Mozhdeh, et al.
(författare)
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Cross-linked superfine electrospun tragacanth-based biomaterial as scaffolds for tissue engineering
- 2016
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Ingår i: European Cells & Materials. - Davos, Switzerland : AO Research Institute Davos. - 1473-2262. ; 31:Suppl. 1, s. 204-204
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Asri, Mohd Afiq Mohd, et al.
(författare)
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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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Ingår i: Lab on a Chip. - : ROYAL SOC CHEMISTRY. - 1473-0197 .- 1473-0189. ; 22:9, s. 1779-1792
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Changsan, Titiwan, et al.
(författare)
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Magnetic microsphere sorbent on CaCO3 templates: Simple synthesis and efficient extraction of trace carbamate pesticides in fresh produce
- 2021
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Ingår i: Food Chemistry. - : Elsevier Applied Science Publishers. - 0308-8146 .- 1873-7072. ; 342
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Tidskriftsartikel (refereegranskat)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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| 5. |
- Liu, Yu, et al.
(författare)
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Facile synthesis of highly processable and water dispersible polypyrrole and poly(3,4-ethylenedioxythiophene) microspheres for enhanced supercapacitive performance
- 2018
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Ingår i: European Polymer Journal. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0014-3057 .- 1873-1945. ; 99, s. 332-339
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Tidskriftsartikel (refereegranskat)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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| 6. |
- Mak, Wing Cheung, 1977-
(författare)
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Biosensor technologies for agriculture and environment - opportunities and challenges
- 2017
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Ingår i: 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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Konferensbidrag (refereegranskat)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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| 7. |
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| 8. |
- Mak, Wing Cheung, 1977-, et al.
(författare)
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Drug delivery into the skin by degradable particles
- 2011
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Ingår i: European journal of pharmaceutics and biopharmaceutics. - : Elsevier. - 0939-6411 .- 1873-3441. ; 79:1, s. 23-27
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Tidskriftsartikel (refereegranskat)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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| 9. |
- Mak, Wing Cheung, et al.
(författare)
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Probing Zinc-Protein-Chelant Interactions using Gold Nanoparticles Functionalized with Zinc-Responsive Polypeptides
- 2014
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Ingår i: Particle & particle systems characterization. - : Wiley-VCH Verlagsgesellschaft. - 0934-0866 .- 1521-4117. ; 31:11, s. 1127-1133
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Tidskriftsartikel (refereegranskat)abstract
- The coordination of zinc by proteins and various other organic molecules is essential for numerous biological processes, such as in enzymatic catalysis, metabolism and signal transduction. Presence of small molecular chelants can have a profound effect on the bioavailability of zinc and affect critical Zn2+-protein interactions. Zn2+ chelators are also emerging therapeutics for Alzheimer’s diseases because of their preventive effect on zinc promoted amyloid formation. Despite the importance of zinc-protein-chelant interactions in biology and medicine, probing such interactions is challenging. Here, we introduce an innovative approach for real-time characterization of zinc-protein-chelant interactions using gold nanoparticles (AuNPs) functionalized with a zinc-responsive protein mimetic polypeptide. The peptide functionalized AuNPs aggregate extensively in the presence of Zn2+, triggered by specific Zn2+-mediated polypeptide dimerization and folding, causing a massive red shift of the plasmon band. Chelants affects the Zn2+- polypeptide interaction and thus the aggregation differently depending on their concentrations, zincbinding affinities and coordination numbers, which affect the position of the plasmon band. This system is a simple and powerful tool that provides extensive information about the interactions of chelants in the formation of Zn2+ coordination complexes and is an interesting platform for development of bioanalytical techniques and characterization of chelation-based therapeutics.
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| 10. |
- Meng, Lingyin, 1991-, et al.
(författare)
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Bi-functional sulphonate-coupled reduced graphene oxide as an efficient dopant for a conducting polymer with enhanced electrochemical performance
- 2020
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry. - 2050-7526 .- 2050-7534. ; 8:37, s. 12829-12839
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Tidskriftsartikel (refereegranskat)abstract
- The rapidly emerging field of organic bioelectronics has witnessed the wide use of conducting polymers (CPs) to fabricate advanced chemically modified electrodes (CMEs) for biosensors and biomedical devices. The electrochemical performance of the CPs in such devices is closely related to the quality and physiochemical nature of the dopants. A bi-functional graphene oxide derivative with high reduction degree and negatively-charged sulphonate functionality, i.e. sulphonate-coupled reduced graphene oxide (S-RGO), was developed and used as an efficient dopant for a CP with enhanced electrochemical performance. The S-RGO was synthesised via a facile one-pot hydrothermal reaction using 4-hydrazinobenzosulphonic acid (4-HBS) as reductant and sulphonate precursor simultaneously. The resulting S-RGO possesses high aqueous dispersion stability (more than 6 months), high electrical conductivity (1493.0 S m−1) and sulphonate functionality. Due to these specific properties, S-RGO demonstrated improved electropolymerisation efficiency for poly(3,4-ethylenedioxythiophene) (PEDOT) proving an effective dopant for the preparation of a PEDOT:S-RGO film (5 mC) with faster polymerisation time (37 s) compared to the conventional 2D dopants GO (PEDOT:GO, 129 s) and RGO (PEDOT:RGO, 66 s). The resulting PEDOT:S-RGO appeared as a homogenous film with uniformly distributed S-RGO dopant, low equivalent series resistance and low charge transfer resistance. Moreover, the electrochemical transduction performance of the PEDOT:S-RGO interface was evaluated with 4 different analytes, including ferric/ferrocyanide redox probe, dopamine, nicotinamide adenine dinucleotide and hydrogen peroxide. As a result of the synergistic effect of S-RGO and PEDOT, the PEDOT:S-RGO demonstrated enhanced electrochemical performance with respect to faster electrode kinetics (smaller ΔEp), ∼2 and ∼4 times increased current responses, and lower peak potentials compared to PEDOT:GO and PEDOT:RGO. This bi-functional S-RGO dopant combined the advantages of conventional GO and RGO to deliver sulphonate functionality and high conductivity for the preparation of advanced PEDOT interface with improved electrochemical performance, that could potentially be applied for applications in electrochemical sensors, biosensors and bioelectronic devices.
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