Abstract: BACKGROUND: 3D printing is an important means to manufacture tissue engineering scaffolds, but how to improve the antibacterial property of scaffolds is an important link that is easily overlooked in current research.
OBJECTIVE: To construct methacrylated gelatin/chitosan antibacterial tissue engineering scaffolds by 3D printing and evaluate the antibacterial properties, mechanical properties, and cell compatibility of the scaffolds.
METHODS: Methacrylated gelatin (3%-15%) and chitosan (0%-5%) were mixed to prepare methacrylated gelatin/chitosan composite bio-inks. The 3D printability of the bio-inks was tested at room temperature, and the appropriate bio-inks were selected for subsequent experiments. 10% methacrylated gelatin was mixed with chitosan of different concentrations (0%, 1%, 3%, and 5%) as bio-inks, and methacrylated gelatin/chitosan scaffolds were 3D printed, which were recorded as G10, G10C1, G10C3, and G10C5, respectively. The effects of the four kinds of bio-inks and four kinds of scaffolds on the growth of Escherichia coli were detected, and the compressive strength and compression modulus of the four kinds of scaffolds were detected. Mouse embryonic fibroblasts NIH3T3 were inoculated on the surface of four scaffolds. The live-dead staining was performed after culturing for 3 days to observe cell viability.
RESULTS AND CONCLUSION: (1) The printing range of pure methacrylated gelatin was between 7% and 13%. The addition of chitosan expanded the printing range of methacrylated gelatin to a lower concentration, which could be as low as 4%. The addition of chitosan to high-concentration methacrylated gelatin increased its viscosity and made it difficult to extrude. Finally, methacrylated gelatin with a concentration of 10% was mixed with 0%, 1%, 3%, and 5% chitosan as bio-ink. (2) With the increase of chitosan concentration, the antibacterial properties of bio-ink and 3D printed scaffolds were enhanced; the compressive strength and compression modulus of 3D printed scaffolds were increased, and the viability of NIH3T3 cells on 3D printed scaffolds increased first and then decreased, among which the cell viability on G10C3 scaffold was the best. (3) The results show that by adjusting the concentration of chitosan and combining 3D printing technology, methacrylated gelatin/chitosan tissue engineering scaffolds with excellent antibacterial properties, mechanical properties and cell compatibility can be obtained.

Key words: 3D printing, tissue engineering scaffold, methacrylated gelatin, chitosan, antibacterial property, engineered bone material