Figure 1

(a) Elasticity of various soft tissues in the human body versus the ratio of collagen type III to collagen type I19, 40, 67,68,69,70; Schematics of conventional tensile and indentation tests, which are widely used for mechanical characterization of soft tissues; (b) Tropocollagen types I and III are shown on the top followed by a schematic of their arrangements to form a heterotypic collagen fibril. The bottom part shows the procedure used to fibrilize tropocollagen types I and III in vitro, followed by sample preparation for atomic force microscopy imaging and nanoindentation. The resulting fibrils include both of the collagen types I and III.