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A multifunctional hydrogel patch with a combination of high toughness, superior adhesion, and good antibacterial effect is a highly desired surgical material. In this study, we developed a novel hydrogel patch composed of poly­(ethylene glycol) diacrylate/quaternized chitosan/tannic acid (PEGDA/QCS/TA) based on mussel-inspired chemistry. The physical and biological properties of the hydrogel patch were systematically evaluated in vitro and in vivo. The results indicated that this hydrogel patch possessed compact microstructure, low swelling ratio, tough mechanical properties, good antibacterial activities against S. aureus and E. coli, and excellent dry/wet adhesive ability to a wide range of substrates. The hydrogel patch could also be degraded and absorbed in vivo and used as a sutureless material for wound closure. All these findings demonstrate that the PEGDA/QCS/TA hydrogel patch with multifunctional properties has great potential for application in biomedical fields.

Nano-hydroxyapatite (HA) was directly synthesized on a silk fibroin (SF) template using the property of SF being soluble in a concentrated CaCl(2) solution as a HA source of calcium at pH 7.4 and room temperature. The microstructure and bonding state were investigated by x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry-thermogravimetry analysis (DSC-TG) and transmission electron microscopy (TEM). The results indicated that the HA crystals were poorly crystallized with a rod-like shape of 20-60 nm length and 10-20 nm diameter. Strong molecular interactions and chemical bonds might be present between SF and HA. There were other nucleation sites such as carbonyl (-C-O) and amine (-N-H-) groups on SF molecules besides the carboxyl (-COOH) and hydroxyl (-OH) groups previously reported. During the formation of HA, the coordination action between specific functional groups on SF and calcium ions (Ca(2+)) played an important role. The crystallinity of HA was improved and had an orientation growth along (0 0 2) at the presence of SF, resulting in a structure similar to natural bone. It was concluded that SF could regulate the structure and morphology of HA effectively.

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