Elucidating polymorph-selective bioadsorption on chitin surfaces

Chitin is a naturally abundant biopolymer with low cytotoxicity offering substantial promise in biomedical applications. An enhanced understanding of the polymorph-selective interactions between proteins and chitin surfaces would enable targeted advances in tissue engineering, antimicrobial surfaces, sensing, and drug delivery. This fundamental understanding is scarce and is challenging to obtain via experimental approaches alone. Molecular simulation approaches can offer complementary insights. Here, we use umbrella sampling molecular dynamics simulations to predict the adsorption free energies of nine representative amino acids at four aqueous chitin interfaces, comprising two chitin polymorphs and two different crystal surfaces. Our results demonstrate a clear selectivity for one polymorph over the other at the amino acid level. From these findings we provide a fundamental basis for explaining the polymorph selectivity exhibited by some chitin binding proteins. Our outcomes offer a platform for the future rational design of polymorph-selective chitin binding motifs.