Electrospun Nanofiber Membranes from 1,8-Naphthimide-Based Polymer/Poly(Vinyl Alcohol) for pH Fluorescence Sensing

Accurately and sensitively sensing and monitoring the pH in the environment is a key fundamental issue for human health. Nanomaterial and nanotechnology combined with fluorescent materials can be emerged as excellent possible methods to develop high-performance sensing membranes and help monitor pH. Herein, a series of fluorescent nanofiber membranes (NFMs) containing poly-1,8-naphthimide derivative-3-[dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]azaniumyl]propane-1-sulfonate (PNI-SBMA) are fabricated by electrospinning the solution of PNI-SBMA blended with poly(vinyl alcohol) (PVA). The surfactant-like functionalities in side chains of PNI-SBMA endow the NFMs with outstanding hydrophilicity, and the naphthimide derivatives are sensitive to pH by photoinduced electron transfer effect, which contribute to highly efficient pH fluorescence sensing applications of NFMs. Specifically, the PNI-SBMA/PVA NFM with a ratio of 1:9 (NFM2) shows high sensitivity and good cyclability to pH. This work demonstrates an effective strategy to realize a fluorescent sensor NFM that has a fast and sensitive response to pH, which will benefit its application of pH sensor monitoring in the water treatment process.

Coaxial electrospinning preparation and antibacterial property of polylactic acid/tea polyphenol nanofiber membrane

The polylactic acid (PLA)/tea polyphenol (TP) nanofiber membranes were prepared by coaxial electrospinning. The physical properties, antibacterial agent release, degradation, and antibacterial properties were investigated. Results demonstrated that stepwise and controlled antibacterial agent release profiles were achieved based on the core-shell configuration and disparate degradation rate of PLA and TP. The mechanical performance decreased with the increase of the TP content in the shell layer. The cumulative antibacterial agent release rate of nanofiber membranes with different TP content was different, while the antibacterial agent release trend was the same. The antibacterial agent release rate of the sample was the fastest at the initial stage from 2 h to 8 h, and then gradually slowed down after 24 h. In addition, the antibacterial activity of the PLA/TP nanofiber membranes was confirmed by the inhibition zone method against both Gram-positive ( Staphylococcus aureus) and Gram-negative ( Escherichia coli). Results showed that the antibacterial performance of PLA/TP nanofiber was intensified with the increasing content of TP, especially had better antibacterial performance against S. aureus.