Preparation and Properties of Cationic Gelatin Cross-Linked with Tannin

A kind of biomaterial with antibacterial and mechanical properties was prepared using gelatin (GE) as a raw material. GE was modified by antibacterial epoxy quaternary ammonium salt (QAS) and then cross-linked with tannic acid (TA). Analysis of the Fourier transform infrared spectroscopy (FTIR) results showed that the cationic group was grafted onto GE by reaction of the amino of GE with the epoxy of QAS, and the cross-linking occurred between the amino of GE and the active groups of TA under alkaline conditions. The cross-linking degree was determined by the fluorescence method via a derivative reaction of fluorescamin. The influence of the cross-linking degree on the physical and chemical properties of the GE film was studied by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and mechanical testing. The results showed that the modified GE film formed a compact cross-linking structure, and its thermostability and mechanical properties were improved with increasing cross-linking degree. The in vitro antibacterial rate of the cross-linked cationic GE film to Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) reached 95.83% and 100% respectively, and the in vitro cell relative growth rate (RGR) of HeLa cells cultured in the extracted leachate of the cross-linked cationic GE film exceeded 85%, which illustrated that the modified GE film had excellent antibacterial activity and biocompatibility.