Stabilization of collagen with EDC/NHS in the presence of l-lysine: A comprehensive study

This paper reports the effect of l-lysine on the conformational, rheological, and thermal properties of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS) cross linked collagen and investigates the influence of l-lysine on the self assembly processes of collagen. In the absence of l-lysine, the rheological characterization of collagen cross linked with EDC/NHS showed an increase in shearing stress with shearing speed indicating that the collagen chains become rigid and the molecules are reluctant to flow. On the other hand, the increase in shearing stress with shearing speed is comparatively much less in the presence of l-lysine indicating a greater flexibility of the collagen molecules. The self assembly processes of collagen treated with EDC/NHS in the absence and presence of l-lysine were characterized using powder XRD, FT-IR, polarizing optical microscopy and kinetic studies. XRD studies show an increase in peak intensity and sharpness in the presence of l-lysine indicating the enhancement of crystallinity of collagen nano-fibrils. FT-IR results suggest that the incorporation of l-lysine in the EDC/NHS cross linking favors the molecular stability of collagen. From the present study, it is possible to conclude that the pre-treatment of collagen with l-lysine enhances EDC/NHS cross linking and can be used for biomaterial applications.