Molecular Dynamics Study of Chitosan Adsorption at a Silica Surface

Magdalena Hudek; Karen Johnston; Karina Kubiak-Ossowska; Valerie A Ferro; Paul A Mulheran

doi:10.1021/acs.jpcc.4c05821

Molecular Dynamics Study of Chitosan Adsorption at a Silica Surface

J Phys Chem C Nanomater Interfaces. 2024 Dec 10;128(50):21531-21538. doi: 10.1021/acs.jpcc.4c05821. eCollection 2024 Dec 19.

Authors

Magdalena Hudek¹, Karen Johnston¹, Karina Kubiak-Ossowska², Valerie A Ferro³, Paul A Mulheran¹

Affiliations

¹ Department of Chemical and Process Engineering, University of Strathclyde, 75 Montrose Street, Glasgow G1 1XJ, U.K.
² ARCHIE-WeSt, Department of Physics, University of Strathclyde, 107 Rottenrow East, Glasgow G4 0NG, U.K.
³ Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, 161 Cathedral Street, Glasgow G4 0RE, U.K.

Abstract

Chitosan is a nontoxic biopolymer with many potential biomedical and material applications due to its biodegradability, biocompatibility, and antimicrobial properties. Here, fully atomistic molecular dynamics simulations and enhanced sampling methods have been used to study the adsorption mechanism of chitosan oligomers on a silica surface from an aqueous solution. The free energy of adsorption of chitosan on a silica surface was calculated to be 0.6 kcal mol^-1 per monomer in 0.15 mol L^-1 aqueous solution, which is comparable to k _B T at room temperature. The loading capacity of chitosan on the silica surface was found to be 0.094 mg m^-2, and it is dominated by charge compensation. Furthermore, the hydrogen bonding between chitosan and silica was analyzed. The nitrogen and hydroxyl group oxygen chitosan atoms were found to be the main contributors to the hydrogen bonding between chitosan and silica. These findings have the potential to guide the experimental design of chitosan-coated silica nanoparticles for applications such as drug delivery or additives for biopolymer food packaging.