The interaction of chitosan and BMP-2 tuned by deacetylation degree and pH value.

Integrating proteins with chitosan (CS) can not only improve the biocompatibility of CS, but also enable the sustained release of proteins. The deacetylation degree (DD) and pH conditions are considered as the two most important factors affecting the interaction between CS and proteins. In this study, the effects of CS with different DDs and pH conditions on bone morphogenetic protein-2 (BMP-2) adsorption were evaluated using the molecular dynamics (MD) method. The results showed that the interaction energy first increased and then decreased, with the increase of the DD in the range of 0-100%; the strongest interaction was found between BMP-2 and 75% DD-CS surface. Furthermore, decreasing pH values favor the interaction between BMP-2 and CS surfaces. These results are useful to gain a better understanding of the interaction mechanism between polysaccharides and proteins and provide a meaningful reference for the application of CS with different DDs and pH conditions.