2.1. Materials

Chitosan-oligosaccharides (CSO, 970Da) were obtained from cool chemical science and technology (Beijing, China), and the degree of deacetylation of CSO is 95%. Cystamine dihydrochloride (98%) and acryloyl chloride (97%) were purchased from Bailingwei Technology Company (Beijing, China). Jiangsu Qiangsheng Functional Chemical Company provided dichloromethane (DCM; analytical grade). Lipo8000™ was provided by Beyotime Biotechnology (Shanghai, China). Fetal bovine serum (FBS), trypsin, and penicillin-streptomycin were purchased from Gibco (USA). Dulbecco’s modified eagle’s medium (DMEM) and Lipo8000™ were supplied by Beyotime Biotechnology (Shanghai, China). GFP antibody, CAT plasmid with N terminal GFP Spark tag, and GFP plasmid was obtained from Sino Biological (Beijing, China). The Fourier-transform infrared spectrometer (FT-IR) is from Thermo Fisher Scientific’s Nicolet™ iS50 FTIR Spectrometer series (Massachusetts, USA). The solid microneedles are from Shanghai Fanzhen Trading Co., Ltd. Catalase detection kits, and Western and IP cell lysates, fixatives, and blocking solutions were purchased from Beyotime Biotechnology Co., Ltd. (Shanghai, China). Nanjing Jiancheng Bioengineering Institute provided alanine aminotransferase and aspartate aminotransferase detection kits (Nanjing, China).