4.4.3 MTT cell proliferation assay of hydrogel
To evaluation the biocompatibility of the hydrogels, the extraction solutions of THB@ANVs hydrogels were first prepared according to ISO 10 993–5 standard. Briefly, the hydrogel (surface area 1 cm2) was soaked in 1 ml DMEM and then placed at 37 ◦C for 24h to obtain the extraction solutions of the hydrogels. Afterward, 106 cells were cultured in the extraction solutions in 96-well plates for 24 h at 37 ◦C and 5% CO2. Then, the medium was replaced with an MTT solution (0.5 mg ml−1) and the plates were placed in an incubator incubated for 4 h. The precipitated formazan was dissolved in isopropanol for 15 min and the absorbance was read at 570 nm.