Modifications of Parylene by Microstructures and Selenium Nanoparticles: Evaluation of Bacterial and Mesenchymal Stem Cell Viability

Parylene-based implants or coatings introduce surfaces suffering from bacteria colonization. Here, we synthesized polyvinylpyrrolidone-stabilized selenium nanoparticles (SeNPs) as the antibacterial agent, and various approaches are studied for their reproducible adsorption, and thus the modification of parylene-C–coated glass substrate. The nanoparticle deposition process is optimized in the nanoparticle concentration to obtain evenly distributed NPs on the flat parylene-C surface. Moreover, the array of parylene-C micropillars is fabricated by the plasma etching of parylene-C on a silicon wafer, and the surface is modified with SeNPs. All designed surfaces are tested against two bacterial pathogens, Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive). The results show no antibacterial effect toward S. aureus, while some bacteriostatic effect is observed for E. coli on the flat and microstructured parylene. However, SeNPs did not enhance the antibacterial effect against both bacteria. Additionally, all designed surfaces show cytotoxic effects toward mesenchymal stem cells at high SeNP deposition. These results provide valuable information about the potential antibacterial treatment of widely used parylene-C in biomedicine.

Solar-Blind Photodetector Based on NaTaO3/TiO2 Composite Film with Enhanced Photoelectric Performance

In this study, ultraviolet detectors based on NaTaO3/TiO2 were fabricated with enhanced detection performance towards solar-blind (200–280 nm) light. A TiO2 seed layer was introduced and served as a buffer layer between the fluorine tin oxide (FTO)-coated glass substrate and the TiO2 film, which increased the adhesion between them. The periodic stability and photoelectric characteristics of the detectors were studied and analyzed. The detectors showed a high performance when illuminated by 265 nm and 254 nm UV light. At −15 V bias, the dark current of the detector was only 70 pA. Under the bias of −15 V and the illumination of 254 nm, the maximum photo-to-dark current ratio reached 20, and the response time was less than 300 ms. Moreover, the detector exhibited a fast response time and remained very stable after numerous testing cycles. These results demonstrate the potential application of NaTaO3/TiO2 composites in UV detection.

Fabrication and Characterisation of Organic EL Devices in the Presence of Cyclodextrin as an Interlayer

This study examined glass-based organic electroluminescence in the presence of a cyclodextrin polymer as an interlayer. Glass-based organic electroluminescence was achieved by the deposition of five layers of N,N’-Bis(3-methylphenyl)N,N’-bis(phenyl)-benzidine, cyclodextrin polymer (CDP), tris-(8-hydroxyquinolinato) aluminium LiF and Al on an indium tin oxide-coated glass substrate. The glass-based OEL exhibited green emission owing to the fluorescence of tris-(8-hydroxyquinolinato) aluminium. The highest luminance was 19,620 cd m−2. Moreover, the glass-based organic electroluminescence device showed green emission at 6 V in the curved state because of the inhibited aggregation of the cyclodextrin polymer. All organic molecules are insulating, but except CDP, they are standard molecules in conventional organic electroluminescence devices. In this device, the CDP layer contained pores that could allow conventional organic molecules to enter the pores and affect the organic electroluminescence interface. In particular, self-association was suppressed, efficiency was improved, and light emission was observed without the need for a high voltage. Overall, the glass-based organic electroluminescence device using CDP is an environmentally friendly device with a range of potential energy saving applications.

Recovery of FTO coated glass substrate via environment-friendly facile recycling perovskite solar cells

Organic–inorganic perovskite solar cells (PSCs) have recently emerged as a potential candidate for large-scale and low-cost photovoltaic devices.

Effects of incorporation of Ag into a kesterite Cu2ZnSnS4 thin film on its photoelectrochemical properties for water reduction

Kesterite Cu2ZnSnS4 (CZTS) thin films in which the Cu site was partially replaced with Ag were prepared by spray deposition on an Mo-coated glass substrate. Successful replacement of Cu components...

Agarose-Chitosan Based Hydrogel Waveguide Matrix: Comparison Synthesis and Performance for Optical Leaky Waveguide (OLW) Biosensor

In this work, a hydrogel-based optical leaky waveguide (OLW) biosensor was developed to detect biomolecules using changes in refractive index (Dn). Hydrogels formed from chitosan and agarose were synthesised to be used as a waveguiding thin film in OLW biosensor. The concentration and thickness of the hydrogels defined by the spin coater speeds and time were optimised to produce a device chip with a single waveguide moded operation of OLW biosensor. The cladding layer was fabricated using 9.5nm titanium coated glass substrate for metal-clad (MCLW) and addition of dye particles (reactive blue 4) for dye-clad (DCLW) format. For the performance of the fabricated device for detection of Dn of a glycerol solution, the highest sensitivity of detection was obtained from MCLW chip made of 2% w/v of chitosan-agarose hydrogel spun at 6000 rpm with LOD: 4.28 x 10–6 RIU, while for DCLW format, the LOD measured at 7.46 x 10–6 RIU. The performance of the device to monitor the protein (bovine serum albumin; BSA and anti-BSA) interaction, the binding affinity in respect of change in peak angle (DӨ°) of chitosan matrix to the protein was measured at DӨ°~(6.2 ± 0.5°)x10–6.