(214ab) Molecular Modeling and Characterization of Dextran-Coated Nanoparticles in Aqueous Medium

Dextran is an important type of polysaccharide that has good biocompatibility, biodegradability, aqueous solubility, and many hydroxyl (-OH) groups for further functionalization. It has also been increasingly used in bio-related applications.  Dextran-coated nanoparticles can represent a material system that provides the benefits of both dextran and nanoparticle simultaneously to further advance the field of nanobiotechnology.  The grafted dextran chains on the nanoparticle surface form a porous layer whose pore structure greatly determines the properties and functions of the nanoparticle but has yet to be characterized.  In this work, the molecular dynamics (MD) methodology is employed to model and simulate dextran-coated solid nanoparticles in an aqueous environment.  A combination of simulation snapshots, dual grid-based pore structure analysis, and radial distributions is use to achieve a quantitative and detailed characterization of the pore structure formed by the dextran chains grafted at a high surface density.  The results show that most of the dextran chains are able to retain highly helical conformations due to their limited structural flexibility from relatively short chain length and additional support from conformationally frozen monomers and a high chain density in the base region.  Although most pore openings are in the smallest size range, in the outer region significantly larger pores exist but become increasingly smaller when the pores extend towards the nanocore.  Water molecules are found to be pervasive throughout the dextran layer and the nanocore surface, indicating good solvation of the dextran-coated nanoparticle by water