Abstract:

Objective To prepare a polyvinyl butyral （PVB） nanofiber membrane loaded with propolis， and to clarify its physicochemical properties， drug release behavior， antibacterial activity， and biocompatibility. Methods Propolis with a mass fraction of 0.12% was dissolved in 18% （mass fraction） PVB methanol solution. PVB and PVB-propolis （PVB-P） nanofiber membranes were prepared using electrospinning from PVB and PVB-P solutions， respectively. Scanning electron microscope （SEM） was used to observe the microscopic morphology of PVB-P nanofibers， and the Nano Measurer software was used to analyze the fiber diameter distribution. Fourier transform infrared spectroscopy （FTIR） was used to analyze the chemical composition of PVB-P. Water contact angle measurements were used to evaluate the hydrophilicity of PVB-P. UV spectrophotometer was used to detect the cumulative release of propolis at different time points. PVB and PVB-P nanofiber membranes were co-cultured with Staphylococcus aureus （S.aureus）， Escherichia coli （E.coli）， Candida albicans （C.albicans）， Salmonella， and Pseudomonas aeruginosa （P.aeruginosa） and divided into PVB group and PVB-P group. The absorbance method was used to calculate the antibacterial values of PVB and PVB-P against the five types of bacteria. The NIH-3T3 cells were seeded on PVB and PVB-P nanofiber membranes and divided into PVB group and PVB-P group. The CCK-8 method was used to detect the survival rates of NIH-3T3 cells on the nanofiber membranes in PVB group and PVB-P group at 1， 3， and 7 d. Results The SEM results showed that PVB and PVB-P nanofibers were interconnected in a mesh-like porous structure， with uniform thickness and no beads. The Nano Measurer software measurement results showed that the diameter of PVB nanofibers was （0.50±0.10） μm， and the diameter of PVB-P nanofibers was （0.54±0.16） μm. FTIR analysis showed that PVB-P nanofiber membranes exhibited characteristic peaks of PVB （1 140 and 1 002 cm^-1） and propolis （1 161 cm^-1）. The water contact angle measurement results showed that the contact angle of PVB membrane was （144.26°±2.90°） and that of PVB-P membrane was （128.13°± 1.36°）. The UV spectrophotometer results showed that the cumulative release of propolis was 0.04 mg at 1 d， 0.07 mg at 3 d， and reached a steady state of 0.79 mg at 7 d. The absorbance method results showed that the antibacterial values of PVB-P nanofiber membranes against S.aureus， E.coli， C.albicans， Salmonella， and P. aeruginosa were 4.39， 1.27， 5.68， 3.16， and 1.87， respectively. The CCK-8 method results showed that the survival rates of NIH-3T3 cells on PVB and PVB-P nanofiber membranes was>90% at 1， 3， and 7 d， and there were no significant differences between various groups （P>0.05）. Conclusion The diameter of PVB nanofiber membranes loaded with propolis is increased， and these membranes exhibit antibacterial effects against S.aureus and C.albicans， while also achieving sustained release of propolis.

Key words: Polyvinyl butyral, Propolis, Electrospinning, Biocompatibility, Antibacterial properties