Formation Mechanism of a Novel Core–Shell with Tetradecyl Dimethyl Benzyl Ammonium–Modified Montmorillonite Interlayer Nanofibrous Membrane and Its Antimicrobial Properties

A novel core–shell with a tetradecyl dimethyl benzyl ammonium chloride–modified montmorillonite (TDMBA/MMT) interlayer silk fibroin (SF)/poly(lactic acid) (PLLA) nanofibrous membrane was fabricated using a simple conventional electrospinning method. Scanning electron microscopy and pore size analyses revealed that this core–shell with TDMBA/MMT interlayer maintained its nanofibrous morphology and larger pore structure more successfully than SF/PLLA nanofibrous membranes after treatment with 75% ethanol vapor. Transmission electron microscopy and energy-dispersive X-ray spectroscopy analyses testified that the SF/PLLA–TDMBA/MMT nanofibers exhibited a core–shell with an interlayer structure, with SF/PLLA in the core–shell layer and TDMBA/MMT in the interlayer. The formation of a core–shell with interlayer nanofibers was primarily attributed to the uniform dispersion of TDMBA/MMT nanosheets in a solution owing to its exfoliation using hexafluoroisopropanol and then preparing a stable spinning solution similar to an emulsion. Compared to SF/PLLA nanofibrous membranes, the core–shell structure with TDMBA/MMT interlayers of SF/PLLA nanofibrous membranes exhibited enhanced hydrophilicity, thermal stability, mechanical properties as well as improved and long-lasting antimicrobial performance against Escherichia coli and Staphylococcus aureus without cytotoxicity.