| 1. |
- Sepehri, Sobhan, 1986, et al.
(författare)
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Volume-amplified magnetic bioassay integrated with microfluidic sample handling and high-Tc SQUID magnetic readout
- 2018
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Ingår i: APL Bioengineering. - : AIP Publishing. - 2473-2877. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- A bioassay based on a high-Tc superconducting quantum interference device (SQUID) reading out functionalized magnetic nanoparticles (fMNPs) in a prototype microfluidic platform is presented. The target molecule recognition is based on volume amplification using padlock-probe-ligation followed by rolling circle amplification (RCA). The MNPs are functionalized with single-stranded oligonucleotides, which give a specific binding of the MNPs to the large RCA coil product, resulting in a large change in the amplitude of the imaginary part of the ac magnetic susceptibility. The RCA products from amplification of synthetic Vibrio cholera target DNA were investigated using our SQUID ac susceptibility system in microfluidic channel with an equivalent sample volume of 3 μl. From extrapolation of the linear dependence of the SQUID signal versus concentration of the RCA coils, it is found that the projected limit of detection for our system is about 1.0 e5 RCA coils (0.2e−18 mol), which is equivalent to 66 fM in the 3 μl sample volume. This ultra-high magnetic sensitivity and integration with microfluidic sample handling are critical steps towards magnetic bioassays for rapid detection of DNA and RNA targets at the point of care.
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| 2. |
- Chen, Zhe, et al.
(författare)
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Nano-scale characterization of white layer in broached Inconel 718
- 2017
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Ingår i: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - Amsterdam : Elsevier BV. - 0921-5093 .- 1873-4936. ; 684, s. 373-384
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Tidskriftsartikel (refereegranskat)abstract
- The formation mechanism of white layers during broaching and their mechanical properties are not well investigated and understood to date. In the present study, multiple advanced characterization techniques with nano-scale resolution, including transmission electron microscopy (TEM), transmission Kikuchi diffraction (TKD), atom probe tomography (APT) as well as nano-indentation, have been used to systematically examine the microstructural evolution and corresponding mechanical properties of a surface white layer formed when broaching the nickel-based superalloy Inconel 718.TEM observations showed that the broached white layer consists of nano-sized grains, mostly in the range of 20–50 nm. The crystallographic texture detected by TKD further revealed that the refined microstructure is primarily caused by strong shear deformation. Co-located Al-rich and Nb-rich fine clusters have been identified by APT, which are most likely to be γ′ and γ′′ clusters in a form of co-precipitates, where the clusters showed elongated and aligned appearance associated with the severe shearing history. The microstructural characteristics and crystallography of the broached white layer suggest that it was essentially formed by adiabatic shear localization in which the dominant metallurgical process is rotational dynamic recrystallization based on mechanically-driven subgrain rotations. The grain refinement within the white layer led to an increase of the surface nano-hardness by 14% and a reduction in elastic modulus by nearly 10% compared to that of the bulk material. This is primarily due to the greatly increased volume fraction of grain boundaries, when the grain size was reduced down to the nanoscale.
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| 3. |
- Eivazihollagh, Alireza, et al.
(författare)
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On chelating surfactants : Molecular perspectives and application prospects
- 2019
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Ingår i: Journal of Molecular Liquids. - : Elsevier BV. - 0167-7322 .- 1873-3166. ; 278, s. 688-705
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Tidskriftsartikel (refereegranskat)abstract
- Chelating agents, molecules that very strongly coordinates certain metal ions, are used industrially as well as in consumer products to minimize disturbances and increase performance of reactions and applications. The widely used sequestering agents, nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) belong to this branch of readily water-soluble compounds. When these chemical structures also have hydrophobic parts, they are prone to adsorb at air-water interfaces and to self-assemble. Such bifunctional molecules can be called chelating surfactants and will have more extended utilization prospects than common chelating agents or ordinary ionic surfactants. The present review attempts to highlight the fundamental behavior of chelating surfactants in solution and at interfaces, and their very specific interactions with metal ions. Methods to recover chelating surfactants from metal chelates are also described. Moreover, utilization of chelating surfactants in applications for metal removal in environmental engineering and mineral processing, as well as for metal control in the fields of biology, chemistry and physics, is exemplified and discussed.
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| 4. |
- Decrop, Deborah, et al.
(författare)
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Single-step manufacturing of femtoliter microwell arrays in a novel surface energy mimicking polymer
- 2015
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Ingår i: 18th International Conference on Solid-State Sensors, Actuators and Microsystems (IEEE TRANSDUCER 2015). - : IEEE.
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Konferensbidrag (refereegranskat)abstract
- We report a novel polymer material formulation and stamp-molding technique that enable rapid single-step manufacturing of hydrophilic-in-hydrophobic microwell arrays. We developed a modified thiol-ene-epoxy polymer (mOSTE+) formulation that mimics the surface energy of its mold during polymerization. The polymer inherits the surface energy from the mold through molecular self-assembly, in which functional monomers self-assemble at the interface between the liquid prepolymer and the mold surface. Combining this novel mOSTE+ material with a stamp-molding process leads to simultaneous surface energy mimicking and micro-structuring. This method was used to manufacture microwells with hydrophilic bottom and hydrophobic sidewall, depressed in a surrounding hydrophobic surface. The microwell arrays were successfully tested for the self-assembly of 62’000 femtoliter-droplets. Such femtoliter droplet arrays are useful for, e.g., digital ELISA and single cell/molecule analysis applications.
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| 5. |
- Surendiran, Pradheebha, et al.
(författare)
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Solving Exact Cover Instances with Molecular-Motor-Powered Network-Based Biocomputation
- 2022
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Ingår i: ACS Nanoscience Au. - : American Chemical Society (ACS). - 2694-2496 .- 2694-2496.
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Tidskriftsartikel (refereegranskat)abstract
- Information processing by traditional, serial electronic processors consumes an ever-increasing part of the global electricity supply. An alternative, highly energy efficient, parallel computing paradigm is network-based biocomputation (NBC). In NBC a given combinatorial problem is encoded into a nanofabricated, modular network. Parallel exploration of the network by a very large number of independent molecular-motor-propelled protein filaments solves the encoded problem. Here we demonstrate a significant scale-up of this technology by solving four instances of Exact Cover, a nondeterministic polynomial time (NP) complete problem with applications in resource scheduling. The difficulty of the largest instances solved here is 128 times greater in comparison to the current state of the art for NBC.
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| 6. |
- Pardon, Gaspard, 1983-
(författare)
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From Macro to Nano : Electrokinetic Transport and Surface Control
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Today, the growing and aging population, and the rise of new global threats on human health puts an increasing demand on the healthcare system and calls for preventive actions. To make existing medical treatments more efficient and widely accessible and to prevent the emergence of new threats such as drug-resistant bacteria, improved diagnostic technologies are needed. Potential solutions to address these medical challenges could come from the development of novel lab-on-chip (LoC) for point-of-care (PoC) diagnostics.At the same time, the increasing demand for sustainable energy calls for the development of novel approaches for energy conversion and storage systems (ECS), to which micro- and nanotechnologies could also contribute.This thesis has for objective to contribute to these developments and presents the results of interdisciplinary research at the crossing of three disciplines of physics and engineering: electrokinetic transport in fluids, manufacturing of micro- and nanofluidic systems, and surface control and modification. By combining knowledge from each of these disciplines, novel solutions and functionalities were developed at the macro-, micro- and nanoscale, towards applications in PoC diagnostics and ECS systems.At the macroscale, electrokinetic transport was applied to the development of a novel PoC sampler for the efficient capture of exhaled breath aerosol onto a microfluidic platform.At the microscale, several methods for polymer micromanufacturing and surface modification were developed. Using direct photolithography in off-stoichiometry thiol-ene (OSTE) polymers, a novel manufacturing method for mold-free rapid prototyping of microfluidic devices was developed. An investigation of the photolithography of OSTE polymers revealed that a novel photopatterning mechanism arises from the off-stoichiometric polymer formulation. Using photografting on OSTE surfaces, a novel surface modification method was developed for the photopatterning of the surface energy. Finally, a novel method was developed for single-step microstructuring and micropatterning of surface energy, using a molecular self-alignment process resulting in spontaneous mimicking, in the replica, of the surface energy of the mold.At the nanoscale, several solutions for the study of electrokinetic transport toward selective biofiltration and energy conversion were developed. A novel, comprehensive model was developed for electrostatic gating of the electrokinetic transport in nanofluidics. A novel method for the manufacturing of electrostatically-gated nanofluidic membranes was developed, using atomic layer deposition (ALD) in deep anodic alumina oxide (AAO) nanopores. Finally, a preliminary investigation of the nanopatterning of OSTE polymers was performed for the manufacturing of polymer nanofluidic devices.
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| 7. |
- Sun, Rui, et al.
(författare)
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Highly Porous Amorphous Calcium Phosphate for Drug Delivery and Bio-Medical Applications
- 2020
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Ingår i: Nanomaterials. - : MDPI. - 2079-4991. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- Amorphous calcium phosphate (ACP) has shown significant effects on the biomineralization and promising applications in bio-medicine. However, the limited stability and porosity of ACP material restrict its practical applications. A storage stable highly porous ACP with Brunauer–Emmett–Teller surface area of over 400 m2/g was synthesized by introducing phosphoric acid to a methanol suspension containing amorphous calcium carbonate nanoparticles. Electron microscopy revealed that the porous ACP was constructed with aggregated ACP nanoparticles with dimensions of several nanometers. Large angle X-ray scattering revealed a short-range atomic order of <20 Å in the ACP nanoparticles. The synthesized ACP demonstrated long-term stability and did not crystallize even after storage for over 14 months in air. The stability of the ACP in water and an α-MEM cell culture medium were also examined. The stability of ACP could be tuned by adjusting its chemical composition. The ACP synthesized in this work was cytocompatible and acted as drug carriers for the bisphosphonate drug alendronate (AL) in vitro. AL-loaded ACP released 25% of the loaded AL in the first 22 days. These properties make ACP a promising candidate material for potential application in biomedical fields such as drug delivery and bone healing.
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| 8. |
- Mellin, Pelle, 1985-, et al.
(författare)
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Nano-sized by-products from metal 3D printing, composite manufacturing and fabric production
- 2016
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Ingår i: Journal of Cleaner Production. - Sweden : Elsevier. - 0959-6526 .- 1879-1786. ; 139, s. 1224-1233
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Tidskriftsartikel (refereegranskat)abstract
- Recently, the health and environmental perspective of nano-materials has gained attention. Most previous work focused on Engineered Nanoparticles (ENP). This paper examines some recently introduced production routes in terms of generated nano-sized by-products. A discussion on the hazards of emitting such particles and fibers is included. Fine by-products were found in recycled metal powder after 3D printing by Selective Laser Melting (SLM). The process somehow generated small round metal particles (~1e2 mm) that are possibly carcinogenic and respirable, but not small enough to enter by skin-absorption. With preventive measures like closed handling and masks, any health related effects can be prevented. The composite manufacturing in particular generated ceramic and carbonaceous particles that are very small and respirable but do not appear to be intrinsically toxic. The smallest features in agglomerates were about 30 nm. Small particles and fibers that were not attached in agglomerates were found in a wide range of sizes, from 1 μm and upwards. Preventive measures like closed handling and masks are strongly recommended. In contrast, the more traditional production route of fabric production is investigated. Here, brushing residue and recycled wool from fabric production contained few nano-sized by-products.
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| 9. |
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| 10. |
- Palo-Nieto, Carlos, 1985-, et al.
(författare)
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Functionalization of cellulose nanofibrils to develop novel ROS-sensitive biomaterials
- 2023
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Ingår i: Materials Advances. - : Royal Society of Chemistry. - 2633-5409. ; 4:6, s. 1555-1565
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Tidskriftsartikel (refereegranskat)abstract
- Wood derived cellulose nanofibrils (CNFs) have emerged as an interesting material for biomedical applications. Functionalization of the nanofibrils with bioactive molecules is a potent tool to tailor CNF materials for specific applications in biomedicine. The present work proposes the functionalization of CNFs with a reactive oxygen species (ROS)-sensitive oligopeptide to develop a novel CNF-based material for the treatment of medical conditions associated with high levels of ROS such as chronic wounds. Oligoproline peptides of two different lengths (5 and 10 proline units) were covalently incorporated onto the CNF surface, several water-based chemical approaches were explored and the reaction conditions to maximize peptide substitution and the degree of fibre crosslinking were optimized. The chemical structure, degree of peptide substitution, degree of fibre crosslinking, surface morphology and ROS-sensitivity of the oligoproline–CNF materials were characterized. Double-crosslinked CNF hydrogels (Ca2+–oligoproline–CNF) were further prepared and the ability of the hydrogels to protect cells from an oxidative environment was investigated in vitro with human dermal fibroblasts, as a first evaluation of the potential of the novel CNF material to be used in chronic wound therapies. Optimization of the reaction conditions resulted in a degree of peptide substitution of 102 ± 10 μmol g−1 CNF irrespective of the oligoproline length and a degree of crosslinking of 55–80% depending on the number of proline units. The results showed that the oligoproline covalently attached to CNFs via carbodiimide chemistry maintained its ability to respond to ROS and that the responsiveness in terms of viscoelastic properties depended on the length of the oligopeptide, with the hydrogel being more responsive when functionalized with 10 proline units compared with 5 proline units. Furthermore, the double crosslinked Ca2+–oligoproline–CNF hydrogels promoted the survival of human dermal fibroblasts exposed to high levels of ROS. This study is the first one to provide an insight into the development of ROS-sensitive materials based on CNFs and opens up possibilities for further investigation on the use of these novel materials in chronic wound care.
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