Abstract
Tropocollagen types I and III were simultaneously fibrilized in vitro, and the differences between the geometric and mechanical properties of the heterotypic fibrils with different mixing ratios of tropocollagen III to I were investigated. Transmission electron microscopy was used to confirm the simultaneous presence of both tropocollagen types within the heterotypic fibrils. The incorporation of collagen III in I caused the fibrils to be thinner with a shorter D-banding than pure collagen I. Hertzian contact model was used to obtain the elastic moduli from atomic force microscope indentation testing using a force volume analysis. The results indicated that an increase in the percentage of tropocollagen III reduced the mechanical stiffness of the obtained fibrils. The mechanical stiffness of the collagen fibrils was found to be greater at higher loading frequencies. This observation might explain the dominance of collagen III over I in soft distensible organs such as human vocal folds.
Highlights
The mechanical strength and elasticity of biological tissues are governed by their constituting protein molecules, only a few nanometers in size, which self-assemble to form fibrils with a hierarchical structure
The purpose of the present study was to investigate the effects of incorporating collagen type III (Col-III) in collagen type I (Col-I) fibrillogenesis for six different mixing ratios of Col-III:Col-I, which were chosen based on those found in various soft tissues as indicated in Fig. 1a, on the mechanical properties and geometric features of the resulting fibrils
We observed a slight decrease in both diameter and D-banding with an increase in the Col-III:Col-I ratios
Summary
The mechanical strength and elasticity of biological tissues are governed by their constituting protein molecules, only a few nanometers in size, which self-assemble to form fibrils with a hierarchical structure. Collagen type III is widely present in collagen I-containing tissues with the exception of bone This fibril-forming collagen is rare in hard tissues and ubiquitous in various elastic tissues such as embryonic skin, lung, and blood vessels, and those found in distensible organs such as vocal folds, bladder, and uterus[18,19,20]. Previous studies have demonstrated that Col-III might be co-expressed with Col-I to form heterotypic fibers (Fig. 1)[28, 33] This co-expression may result in the regulation of the dimensions of the fibrils, such as their diameter[27, 34, 35]. Taatjes et al.[49] used AFM imaging to investigate the morphological properties of Col-III fibrils
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
