Structural and mechanical behavior of type-I collagen fibrils in presence of induced electrostatic interactions through ionic liquids.

Tuning the self-assembly of collagen has broad applications in the biomedical field owing to their desired biological performance as collagenous materials with tunable functionalities can further determine cellular responses. In this work, an attempt has been made to tune the self-assembly of collagen using ionic liquids, viz., imidazolium chloride (IC) and choline dihydrogen phosphate (CDHP) at its physiological pH, followed by probing assembled systems using various characterization methods. Turbidity measurements of fibrillar networks were performed to ascertain the rate of fibril formation in addition of imidazolium chloride and choline dihydrogen phosphate to collagen at physiological pH. Morphological changes were examined using Scanning Electron Microscope (SEM), binding affinities were measured by Microscale Thermophoresis (MST), in addition to, changes in the shear viscosity, mechanical strength of collagen fibrils when interacted with imidazolium and choline based ILs were carried out using rotational rheometer and Quartz Crystal Microbalance (QCM) measurements. Experimental result depicts that CDHP imparts better crosslinking as well as mechanical strength compare to IC, which is already known for destabilizing the triple helix structure is inhibiting the fibril formation. This self-assembled, ionic-liquid treated collagen-fibrillar system would accelerate various force modulated fibrillar network study, for mimicking the ECM and tissue engineering application.