| 1. |
- Semchuk, O. Yu., et al.
(författare)
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Features of transport phenomenas in magnetic semiconductors with laser-induced periodic nanostructures
- 2007
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Ingår i: Materials Science & Engineering. - : Elsevier BV. - 0921-5093 .- 1873-4936 .- 0928-4931 .- 1873-0191. ; 27:5-8, s. 1360-1363
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms of formation of the laser-induced periodic surface and bulk nanostructures in magnetic semiconductors are considered. Their influence on transport phenomena in ferromagnetic semiconductors (FMSC) is investigated. It is shown that under action of laser beams (LB) a laser-induced periodic nanostructures — gratings of the electron and magnon temperatures, electron concentration and electric fields arises in FMSC. It is determined, that the illuminating of an external surface of the FMSC by several LB results in an emerging new effect — appearance of a dropping site on the voltage-current characteristic (VCC) of the FMSC with the static laser-induced periodic nanostructures. This effect can only be observed for the carrier concentration n ≥ 1018 cm−3, since for smaller concentration the contribution of an additional current caused by the presence of the laser-induced periodic nanostructures will be insignificant.
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| 2. |
- Almqvist, Nils, et al.
(författare)
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Methods for fabricating and characterizing a new generation of biomimetic materials
- 1999
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Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems. - 0928-4931 .- 1873-0191. ; 7:1, s. 37-43
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Tidskriftsartikel (refereegranskat)abstract
- Bringing together current ideas in the fields of biomineralization and composite laminate materials, we have attempted to fabricate model materials that mimic abalone nacre through the rapid assembly of inorganic tablets, such as talc. Several physical methods were tested to aid the orientation of the talc tablets in fluid suspensions with a low percentage, 10% by dry weight, of organic binding material. The orientation of talc tablets in the synthesized composites was characterized by X-ray diffraction and scanning electron microscopy. The modulus of rupture of the materials was measured in a three-point bending test. We demonstrate that the alignment of tablets increases by the use of physical methods and from chemical surface treatment. Important factors to consider in making materials that mimic abalone nacre are discussed. Important factors to consider in making materials that mimic abalone nacre are discussed.
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| 3. |
- Donchev, V., et al.
(författare)
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Photoluminescene line-shape analysis in quantum wells embedded in superlattices
- 2001
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Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems. - 0928-4931 .- 1873-0191. ; 15:1-2, s. 75-77
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Tidskriftsartikel (refereegranskat)abstract
- The temperature evolution of the main photoluminescence (PL) mechanisms, in GaAs quantum wells embedded in short-period AlAs/GaAs superlattices, is investigated. PL spectra are measured from 2 to 300 K. A detailed line-shape analysis of the PL peaks is performed by means of a statistical model, including both free exciton and free carrier recombination. The fits based on this model reproduce satisfactorily the experimental PL line shapes and allow to assess quantitatively the relative contributions of free excitons and free carriers to the radiative recombination at different temperatures. The results indicate the predominant role of free excitons in the radiative recombination up to room temperature, and are consistent with the mass action law. © 2001 Elsevier Science B.V. All rights reserved.
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| 4. |
- Lundqvist, Andreas, et al.
(författare)
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Frontal affinity chromatographic analysis of membrane protein reconstitution
- 1997
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Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems. - 0928-4931 .- 1873-0191. ; 4:4, s. 221-226
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Tidskriftsartikel (refereegranskat)abstract
- The human red cell glucose transporter Glut1 was solubilized with octaoxyethylene n-dodecyl ether (low critical micelle concentration (CMC)), purified, mixed with egg phospholipids and cholate, and reconstituted by gel filtration on Superdex 75. Free protepliposomes showed relatively high D-glucose transport activity. Frontal affinity chromatographic analysis with the proteoliposomes sterically immobilized in Superdex 200 gel beads revealed that the number of operative cytochalasin B (CB) binding sites increased during the first days of chromatographic runs to become the same as with 1-O-n-octyl β-d-glucopyranoside (high CMC) as solubilizer and Sephadex G-50 as gel filtration medium. The average number of sites per Glut1 monomer was 0.32 ± 0.02. The average Kd for CB was 66 ± 3 nM at 150 mM NaCl, similarly as for Glut1 in membrane vesicles, whereas the affinity of d-glucose for reconstituted Glut1 was lower (Kd = 44 ± 3 mM) than for membranous Glut1 (Kd = 15 ± 5 mM). Two theoretical treatments of affinity chromatographic data gave the same values in agreement with competitive and monovalent interactions.
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| 5. |
- Alaghmandfard, A., et al.
(författare)
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Recent advances in the modification of carbon-based quantum dots for biomedical applications
- 2021
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Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems. - : Elsevier BV. - 0928-4931 .- 1873-0191. ; 120
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Forskningsöversikt (refereegranskat)abstract
- Carbon-based quantum dots (CDs) are mainly divided into two sub-groups; carbon quantum dots (CQDs) and graphene quantum dots (GQDs), which exhibit outstanding photoluminescence (PL) properties, low toxicity, superior biocompatibility and facile functionalization. Regarding these features, they have been promising candidates for biomedical science and engineering applications. In this work, we reviewed the efforts made to modify these zero-dimensional nano-materials to obtain the best properties for bio-imaging, drug and gene delivery, cancer therapy, and bio-sensor applications. Five main surface modification techniques with outstanding results are investigated, including doping, surface functionalization, polymer capping, nano-composite and core-shell structures, and the drawbacks and challenges in each of these methods are discussed.
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| 6. |
- Alenezi, Ali, et al.
(författare)
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Development of a photon induced drug-delivery implant coating
- 2019
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Ingår i: Materials Science and Engineering C. - : Elsevier BV. - 0928-4931 .- 1873-0191. ; 98, s. 619-627
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Tidskriftsartikel (refereegranskat)abstract
- A thin surface coating intended for medical devices such as implants where local drug release is enabled using near infrared light (NIR) as an external stimulus has been developed. The delivery system consists of a thin Poly (N-isopropylacrylamide)-co-acrylamide (PNIPAAm-AAm) polymer layer with incorporated gold nanorods (GNRs). The aspect ratio of the GNRs were chosen to absorb NIR light, thus fitting the biological window of low tissue absorption, to locally heat the polymeric layer to initiate a drug release. Hence, controlled drug delivery from a surface within tissue orchestrated from outside the body is achievable. Composition of the PNIPAAm-AAm co-polymer was systematically varied to find a suitable phase transition temperature for in vivo applications. Differential scanning calorimetry (DSC) analysis showed that PNIPAAm-AAm containing 10% acrylamide had an appropriate phase transition temperature of 42 °C. As visualized by scanning electron microscopy (SEM), the surface coating consisted of 200 nm uniform polymer layer. Quartz crystal microbalance with dissipation monitoring (QCM-D) analysis coupled with in situ NIR irradiation demonstrated a dramatic shift in frequency that was attributed to mass being released from the surface upon irradiation. This mass release correlated well with the drug release profile as determined using UV/VIS spectroscopy with phenol as a model drug. In addition, proof-of-concept of the drug-delivery system was demonstrated by releasing the antibiotic vancomycin to eradicate Staphylococcus epidermidis bacteria in culture.
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| 7. |
- Battocchio, Chiara, et al.
(författare)
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Chitosan functionalization of titanium and Ti6Al4V alloy with chloroacetic acid as linker agent
- 2019
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Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems. - : ELSEVIER SCIENCE BV. - 0928-4931 .- 1873-0191. ; 99, s. 1133-1140
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Tidskriftsartikel (refereegranskat)abstract
- In this work, a new covalent grafting of chitosan on titanium and Ti6Al4V alloy surfaces is reported using chloroacetic acid as linker agent. Good results were obtained both on titanium and on Ti6Al4V alloy. The effect of the surface acid pretreatments on the subsequent functionalization with chitosan is evaluated. The morphological aspect of acid etched metal surfaces before chitosan grafting has been characterized by scanning electron microscopy (SEM). The presence of carboxylic groups on metal surfaces and then the efficiency of chitosan covalent immobilization were detected by Fourier transformed infrared-Attenuated Total Reflectance (FTIR-ATR) and X-Ray photoelectron spectroscopy (XPS). Cyclic voltammetry tests, using the functionalized titanium and Ti6Al4V samples as electrodes, were conducted in different aqueous solutions, to detect the presence of the homogeneous overlayer of chitosan on the surface, and to evaluate the importance of the carboxyl groups as linker agent.
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| 8. |
- Brown, Toby D, et al.
(författare)
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Melt electrospinning of poly(ε-caprolactone) scaffolds : phenomenological observations associated with collection and direct writing.
- 2014
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Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems. - : Elsevier BV. - 0928-4931 .- 1873-0191. ; 45
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Tidskriftsartikel (refereegranskat)abstract
- Melt electrospinning and its additive manufacturing analogue, melt electrospinning writing (MEW), are two processes which can produce porous materials for applications where solvent toxicity and accumulation in solution electrospinning are problematic. This study explores the melt electrospinning of poly(ε-caprolactone) (PCL) scaffolds, specifically for applications in tissue engineering. The research described here aims to inform researchers interested in melt electrospinning about technical aspects of the process. This includes rapid fiber characterization using glass microscope slides, allowing influential processing parameters on fiber morphology to be assessed, as well as observed fiber collection phenomena on different collector substrates. The distribution and alignment of melt electrospun PCL fibers can be controlled to a certain degree using patterned collectors to create large numbers of scaffolds with shaped macroporous architectures. However, the buildup of residual charge in the collected fibers limits the achievable thickness of the porous template through such scaffolds. One challenge identified for MEW is the ability to control charge buildup so that fibers can be placed accurately in close proximity, and in many centimeter heights. The scale and size of scaffolds produced using MEW, however, indicate that this emerging process will fill a technological niche in biofabrication.
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| 9. |
- Bäckdahl, Henrik, 1977, et al.
(författare)
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Observations on bacterial cellulose tube formation for application as vascular graft
- 2011
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Ingår i: Materials Science and Engineering C. - : Elsevier BV. - 0928-4931 .- 1873-0191. ; 31:1, s. 14-21
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Tidskriftsartikel (refereegranskat)abstract
- Nanocellulose (bacterial cellulose, BC), such as that produced by Acetobacter xylinum, has shown promising results as a replacement material for small diameter vascular grafts. The surface morphology of the lumen and mechanical properties of such tubes are crucial for their performance. The growth of a BC tube in a vertical fermentation bioreactor using silicone tubing for support and as an oxygen delivery membrane has not been studied in detail previously. Oxygen concentration and the number of bacteria added influence the production of the BC tubes. A dense and smooth luminal surface was formed after 4 days on a 3 mm silicone support. The bacteria were found to be in high concentration close to the silicon support and decreased in number further away. In the region with a high bacteria concentration, dense thin layers of BC were formed since the bacteria moved close together in this region. The presented observations were summarized in a theoretical model of BC tube growth.
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| 10. |
- Caccavo, Diego, et al.
(författare)
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Modeling capillary formation in calcium and copper alginate gels.
- 2016
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Ingår i: Materials Science and Engineering C. - : Elsevier BV. - 0928-4931 .- 1873-0191. ; 58, s. 442-449
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Tidskriftsartikel (refereegranskat)abstract
- Alginate solutions in the presence of bivalent ions can form ionic cross-linked gels. In particular gelation conditions the gel structure can be characterized by great anisotropy with the presence of straight capillaries along a preferential direction. These materials can find applications mainly in high-tech sectors, like tissue engineering, where the gel characteristics play a crucial role. Despite the need of mastering the capillary formation and properties, the process remains a poorly known problem, and its development is left to trial and error procedures. In this work a quantitative approach to the description of the capillary formation process has been developed. The theory proposed by Treml et al. (2003) has been implemented and extended to an alginate different from the one used in that study and two different ions (calcium and copper). Some of the model parameters have been derived through simple measurements; others have been scaled using proper scaling equations. Experiments have been performed in different gelation conditions, varying alginate and ionic solution concentrations, to highlight the effects of these parameters on the anisotropic structure and to validate the model. In all the analyses done, the model has performed nicely showing a good reliability in the prediction of gel characteristics like capillary formation, capillary length and process time.
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