Abstract
In this study, ʟ-alanine were copolymerized at both ends of poly(ethylene glycol) forming a triblock copolymer PA-PEG-PA(PEA) to promote cell adhesion. Then the terminal group of PEA were modified by acryloyl group to make it an amphiphilic block copolymer with photo-crosslinking property. After modification of terminal group, the material can be exposed to ultraviolet light (UV light) to induce photo-polymerization, and obtain photocrosslinked hydrogels which have greater mechanical strength. We observe and measure the gel fraction, water content, structure and mechanical property of hydrogels in different concentration. The results showed that hydrogels with concentration of 10 wt% had better gelation property and mechanical strength. According to the results of hydrogel toxicity test, soaking the hydrogel in the medium can effectively remove the unreacted polymer and the remained photoinitiator to reduce the toxicity of hydrogel. The cell viability all maintained at more than 90%. Subsequently, cells and hydrogels were co-cultured to observe cell viability and the growth in the hydrogel. According to the results of MTT assay, the cell survival rate of the seventh day was higher than the fourth day, demonstrating that the cells can grow in this environment very well. However, Live/Dead assay results showed that cells migrated into PEA-DA hydrogel instead of attaching to the surface of the hydrogel. Functional characterization of human umbilical vein endothelial cells (HUVECs) was performed by quantitative reverse transcriptase polymerase chain reaction and immunofluorescence staining afterwards. As a result, it was found that the specific gene expression of the PEA-DA hydrogel group was higher than the PEG-DA hydrogel group after seven days of co-culture, demonstrating that the PEA-DA hydrogel which copolymerized with Alanine does not help much in improving the cell survival rate, but the human umbilical vein endothelial cells express higher specific gene expression compared with PEG-DA hydrogel in the long-term cultivation.