Biomolecule immobilization has attracted the attention of various fields such as fine chemistry and biomedicine for their use in several applications such as wastewater, immunosensors, biofuels, et cetera. The performance of immobilized biomolecules depends on the substrate and the immobilization method utilized. Electrospun nanofibers act as an excellent substrate for immobilization due to their large surface area to volume ratio and interconnectivity. While biomolecules can be immobilized using adsorption and encapsulation, covalent immobilization offers a way to permanently fix the material to the fiber surface resulting in high efficiency, good specificity, and excellent stability. This review aims to highlight the various covalent immobilization techniques being utilized and their benefits and drawbacks. These methods typically fall into two categories: (1) direct immobilization and (2) use of crosslinkers. Direct immobilization techniques are usually simple and utilize the strong electrophilic functional groups on the nanofiber. While crosslinkers are used as an intermediary between the nanofiber substrate and the biomolecule, with some crosslinkers being present in the final product and others simply facilitating the reactions. We aim to provide an explanation of each immobilization technique, biomolecules commonly paired with said technique and the benefit of immobilization over the free biomolecule.

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The Materials Cycle 2 Typical Conversion Chain or Matrix 3 Overview of the Methodology 4 Screening System .

Silver-doped carbon nanofibers (SDCNF) are used as the base material for the selective capture of Escherichia coli in microfluidic systems. Fibers were spun in a glovebox with dry atmosphere maintained by forced dry air pumped through the closed environment. This affected the evaporation rate of the solvent during the electrospinning process and the distribution of silver particles within the fiber. Antibodies are immobilized on the surface of the silver-doped polyacrylonitrile (PAN) based carbon nanofibers via a three-step process. The negatively charged silver particles present on the surface of the nanofibers provide suitable sites for positively charged biotinylated poly-(L)-lysine-graft-poly-ethylene-glycol (PLL-g-PEG biotin) conjugate attachment. Streptavidin and a biotinylated anti-E. coli antibody were then added to create anti-E. coli surface functionalized (AESF) nanofibers. Functionalized fibers were able to immobilize up to 130 times the amount of E. coli on the fiber surface compared to neat silver doped fibers. Confocal images show E. coli remains immobilized on fiber mat surface after extensive rinsing showing the bacteria is not simply a result of non-specific binding. To demonstrate selectivity and functionalization with both gram negative and gram-positive antibodies, anti-Staphylococcus aureus surface functionalized (ASSF) nanofibers were also prepared. Experiments with AESF performed with Staphylococcus aureus (S. aureus) and ASSF with E. coli show negligible binding to the fiber surface showing the selectivity of the functionalized membranes. This surface functionalization can be done with a variety of antibodies for tunable selective pathogen capture.

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Interest in bifacial modules has rapidly increased over the past decade due to their ability to generate more power than conventional monofacial photovoltaic (PV) technology as they can absorb sunlight from both sides of the module. Compared to the traditional glass/glass bifacial modules, glass/backsheet modules show many advantages including lighter weight, high light transmittance, and high corrosion resistance. However, research on the weatherability and long-term reliability of transparent backsheet materials and their usage in bifacial modules under service environments is lacking. In this study, accelerated weather testing using the NIST SPHERE (Simulated Photodegradation via High Energy Radiant Exposure) was conducted to investigate the durability of three fluoropolymer-based transparent backsheets and their laminated coupon counterparts. The transparent backsheets were exposed at 75 C/50% relative humidity (RH), while the coupons were exposed at 65 C/50% RH, both subjected to UV irradiance of approximately 140 W/m 2 for up to 2000 h. Results indicate that a fluoroethylene vinyl ether (FEVE)/polyethylene terephthalate (PET)/ethylene-vinyl acetate (EVA)-based transparent backsheet (CB3) exhibited substantial chemical, optical, thermal, and mechanical changes and ultimate cracking after 1200 h (≈600 MJ/m 2 ). The other two backsheets, polyvinyl fluoride (PVF)/PET/FEVE-based (CB1) and polyvinylidene fluoride (PVDF)/PET/FEVE-based (CB2) backsheets, showed no obvious signs of cracking up to 2000 h of UV exposure(≈1000 MJ/m 2 ). For all three backsheets, the PET core layer demonstrated the greatest material property changes after UV exposure indicating that this layer is the most susceptible to UV degradation. Results indicate that the application of transparent backsheets for bifacial modules is promising. However, proper design of the layers of the backsheets for increasing the stability of PET core layer under UV exposure is critical. This study will provide a scientific basis for material choice and product development for a more reliable bifacial PV technology.

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