Ties That Bind: Evaluation of Collagen I and α-Chitin

Abstract

Collagen and chitin are two fascinating unique matrix framework molecules that play a key role in the hierarchical development of hard tissue. Of the 28 identified types, collagen I accounts for more 90% of the total collagen found in nature and is the main constituent of bone. Of the three identified types, α-Chitin is the most abundant form found in nature and is the main component in the exoskeletons of crustaceans like crabs. α-chitin is a plentiful natural material, similar to collagen I in composition, structure, and function. Both collagen I and α-chitin have extensive use in the biomedical field. In an effort to obtain processing strategies and microstructure design criteria for the development of new bone substitute materials with novel properties, biomimetics was used to establish relationships between the properties of collagen I and α-chitin. The objective of this study was to compare collagen I and α-chitin to illuminate notable similarities and differences in chemical, physical, structural and functional properties. The more intriguing similarities involve hierarchical structuring, liquid crystal characteristics and self assembly. One of the more conspicuous differences is the biochemistry of collagen I, a protein, and α-chitin, a polysaccharide. Collagen I and α-chitin were studied using electron microscopy, elemental and thermal analysis. Bouligand or a twisting plywood system was observed on both collagen and chitin micrographs. One major difference is that the SEM micrographs of collagen fibers demonstrated a banding pattern while chitin fibers did not. The elemental analysis revealed that chitin’s carbon/nitrogen of 3 was doubled in collagen. Thermal analysis revealed that chitin had two thermal transitions while collagen had three. Both collagen and chitin have a thermal event associated with the evolution of freely bound water. These are among the similarities and differences that will be addressed in this paper.