Bioactivity of star-shaped polycaprolactone/chitosan composite hydrogels for biomaterials

Recently, our group reported the synthesis and fabrication of composite hydrogels of chitosan (CS) and star-shaped polycaprolactone (stPCL). The co-crosslink of modified stPCL with carboxyl at the end chain (stPCL-COOH) provided good mechanical properties and stability to the composite hydrogels. This research presents the bioactivities of composite hydrogels showing a potential candidate to develop biomaterials such as wound dressing and bone tissue engineering. The bioactivities were the antibacterial activity, cell viability, skin irritation, decomposability, and ability to attach ions for apatite nucleation. The results showed that all the composite hydrogels were completely decomposed within 2 days. The composite hydrogels had better antibacterial activity and higher efficiency to Gram-negative (Escherichia coli) than to Gram-positive (Staphylococcus epidermidis) bacteria. The composite hydrogels were studied for cell viability based on MTT assay and skin irritation on rabbit skin. The results indicated high cell survival more than 80% and no skin irritation. In addition, the results showed that calcium and phosphorous were preferentially attached to the composite hydrogel surface to grow apatite crystal (Ca/P ratio 1.86) compared to attaching to the chitosan hydrogel (Ca/P ratio 1.48) in 21 days of testing.