Characterization of AgNPs-Reinforced Silk Fibroin Fibers

The ultraviolet–visible (UV–Vis) spectra of AgNPs were measured with a UV–Vis spectrophotometer (UV1000F, Labsphere, Halma, NH, USA). The morphology of AgNPs was investigated by transmission electron microscopy (TEM, Tecnai 12, Philips, Amsterdam, The Netherlands). The diameter and morphology of the RSF fibers were characterized via a scanning electron microscope (SEM, Quanta 400 FEG, Reston, VA, USA). The mechanical testing of the RSF fibers was performed by a universal testing machine (Instron 3343, Norwood, MA, USA) in a constant-temperature and -humidity room (24 °C, 65% RH), with a gauge length of 6 mm and a loading rate of 2 mm·min⁻¹. At least 20 fibers (6 mm) from the same sample were selected for mechanical testing, and the stress–strain data closest to the average value of 20 fibers (6 mm) was the final representative data of the sample. The structure of RSF/AgNPs hybrid fibers were analyzed by wide-angle X-ray diffraction (WAXD) (Rigaku TTR-III, Tokyo, Japan). Fourier transform infrared (FTIR) spectra of RSF/AgNPs hybrid fibers were characterized by the Shanghai Synchrotron Radiation Facility (SSRF).