Quasi-static and dynamic mechanical properties of artificial tissue fabricated from concentrated collagen using mechano-chemical treatment

The present study sought to develop artificial tissues possessing mechanical properties similar to those of human tendons. Collagen solution, concentrated via dialysis, was used to form a collagen gel . The gel was then subjected to mechano-chemical treatment, applying a 20-g static mechanical loading and a chemical cross-linker, genipin , to collagen gel at 37 °C for 48 h, to shape the gel into artificial tissue by inducing longitudinal alignment of collagen fibres and enhancing cross-linking between them (20gStretch tissue). To characterise mechanical and biological properties, quasi-static and dynamic tensile tests , as well as a biocompatibility test, were performed. 20gStretch tissue possessed tensile strength of 10 MPa, tangent modulus of 317 MPa, and strain at failure of 4.2 %. Stress relaxation was ∼20 %. Hysteresis loss was ∼20 %, and residual strain was ∼30 % of the magnitude of the applied strain when subjected to 2 % and 4 % cyclic stretching. These properties were significantly more tendon-like than tissues made without mechanical loading (Static tissues). Indeed, collagen fibres in 20gStretch tissue were well aligned to the loading direction, which was not observed in Static tissues. When embedded along rat Achilles tendon , 20gStretch tissues induced only a minimal inflammatory reaction and maintained tissue integrity for 12 weeks. Although only the modulus of 20gStretch tissue reached the level of human tendon, other properties, such as strength and extensibility require further improvement. Nonetheless, our method fabricated highly elastic, biocompatible, artificial tissues. • Mechano-chemical treatment aligned and strengthened collagen fibres. • Artificial tissue made from concentrated collagen solution achieved 10 MPa strength. • Artificial tissue exhibited elastic and less viscous behaviours to cyclic loading.