Characterization of Type I Collagen Fibrillogenesis Using Atomic Force Microscopy

Abstract

Bone is a 'smart' material adapting its material composition and properties in response to external loading to maintain the mechanical integrity. Thus, understanding the mechanism to control its adaptive behavior is extremely useful not only for improving clinical treatment but also for mimicking its design strategy for boundless engineering applications. As one of the bone's main constituents, collagen type I is the most abundant protein consisting of osseous tissue. The bio-mineralization process of collagen template controls the mechanical stiffness of bone in response to external loading. While the involvement of collagen in the bone mineralization process is widely accepted, its role and mechanism have not been fully understood yet. As a long-term goal of this research, we aim to investigate the role of collagen in transducing the mechanical input to the biological signal in the process of bone mineralization. For this purpose, it is required to fabricate the collagen template in vitro with varying density and fibril arrangements in a controlled fashion. Here, in vitro fibrillogenesis of the collagen is investigated depending on the fabrication conditions such as ion concentration, pH level, and collagen concentration. Atomic Force Microscopy (AFM) is employed to characterize the growth of fibril width, alignment, and density of the assembled collagen matrix. The self-assembly property of the collagen on various conductive substrates such as gold and platinum are also studied to prepare the collagen-coated samples for future research of piezoelectric property of the collagen.