Synthesis and characterization of type I collagen-based scaffolds cross-linked with natural polyphenols extracted from green tea    

Collagen, thanks to its high biocompatibility, low immunogenicity, and ability to mimic the extracellular matrix (ECM), is a promising candidate for soft tissue repair. However, its poor mechanical properties and rapid in vivo degradation limit its use in high-stress environments. This study focused on the cross-linking of type I collagen-based scaffolds with a natural extract from green tea (TPHs). This extract can provide collagen cross-linking and additional anti-inflammatory and antioxidant properties.

Type I collagen scaffolds obtained through the lyophilization of type I collagen hydrogels were immersed in TPHs-PBS solutions at different concentrations. Samples were characterized by several techniques (ATR-FTIR, FE-SEM, DSC, XRD, swelling and compression tests, UV-VIS spectroscopy, release tests, and zeta potential measurements) to investigate if the cross-linking process caused collagen denaturation, how different concentrations of TPHs affected the physico-chemical properties of the hydrogel, and the dynamics of TPHs release in a physiological solution.

Results confirmed TPHs as an effective cross-linking agent without causing collagen denaturation. Samples cross-linked with TPHs registered elastic moduli as high as 7 kPa with an increment of 180 %. Release tests evidenced a slow release of a fraction of the TPHs after an initial (1 h) burst release, making these constructs suitable for a sustained action up to 14 days.