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Enzyme-linked immunoassay (ELISA) is highly specific and selective towards target molecules and is convenient for on-site detection. However, in many cases, lack of high sensitivity makes it hard to reveal a significant colorimetric signal for detecting a trace amount of target molecules. Thus, analytical instruments are required for detection, which limits the application of ELISA for on-site detection. In the present study, a highly sensitive and naked-eyed detectable colorimetric biosensor for chloramphenicol (CAP) was prepared by incorporating ELISA onto surfaces of microporous and nanofibrous membranes. The high specific surface areas of the nanofibers significantly increased the number of antibodies covalently linked onto the fiber surfaces and binding capacity of the sensor with antigens present in a sample. With such an integration, the sensitivity of the ELISA sensor was dramatically increased, and a trace number of targets could reveal a naked-eye detectable color. The immunoassay sensor exhibited a significant naked-eye distinguishable color to chloramphenicol (CAP) at 0.3 ng/mL. The successful design and fabrication of the nanofibrous membrane immunoassay sensor provide new paths towards the development of on-site inspection sensors without the assistance from any instrument., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Poly (vinyl alcohol-co-ethylene) nanofibrous membranes (PVA-co-PE NFM) were successfully modified by sodium-3-sulfobenzoate to become negatively charged with sulfonate groups, and the sulfonated (PVA-co-PE) nanofiber membrane SS (PVA-co-PE NFM) was used in non-covalent adsorption of cellulases via electrostatic attraction. The modified NFM showed excellent adsorption to the enzyme molecules due to the incorporated static charge interaction with the fibers, high open-porosity and ultrahigh surface areas of the nanofibers. Such unique morphology and chemical structures lead to the adsorption capacity of 130 mg g -1 and reusability for 5 cycles without significant change in catalytic functions. The morphology changes of the nanofibrous membranes were observed by using a scanning electron microscopy, and chemical structures of the membranes were characterized by using FTIR and water contact angle measurements. SS (PVA-co-PE NFM) is a promising solid support media for enzyme immobilization, and the immobilized enzymes can be applied in industrial applications., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Fabricating adsorptive materials for fast and high efficient adsorption of enzymes is critical to match the great demands for separation and recovery of enzymes used as biocatalysts. However, it has proven extremely challenging. Here, we report a cost-effective strategy to construct the sulfated group surface-functionalized silk fibroin nanofibrous membranes (SS-SFNM) under mild conditions for positively charged Candida rugosa lipase adsorption. The naturally abundant silk is thus reconstructed into nanofibrous membranes with tunable surface functions. Thereby, the resultant SS-SFNM exhibited excellent adsorption performance towards lipase, including a superior adsorption capacity of 148 mg g -1 , fast adsorption equilibrium within 3 h and good reversibility. The fabrication of such fascinating silk-based materials may provide new chance into the design and development of multi-functional membranes for various separated applications., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this study, polyanionic alginate gel beads crosslinked by Ca 2+ and glutaraldehyde have demonstrated a strong electrostatic interaction with specific proteins. Due to the naturally abundant carboxyl groups, the prepared alginate gel beads exhibited a relatively superior integrated adsorption performance toward lysozyme, including a superior adsorption capacity of 213mgg -1 , fast adsorption equilibrium within 12h, good selectivity, and good reversibility. Compared with other protein adsorbents, the as-prepared adsorptive beads have the advantages of excellent adsorption performance, easy to prepare, convenient, efficient, reliable and environment-friendly to apply, which can serve as a more sustainable material in protein separation and purification., (Copyright © 2017. Published by Elsevier B.V.)