ATOMISTIC MOLECULAR DYNAMICS SIMULATIONS OF THERMALLY RESPONSIVE POLYMERIC DRUG CARRIERS

Abstract

Atomistic simulations of a single, multiple chain syndiotactic poly(N-isopropylacrylamide) (PNIPAM) oligomers and block copolymer of poly(NIPAAm-b-TMC) with indomethacin drug model were performed using the GROMACS software package in aqueous solution at temperatures below and above the LCST of PNIPAM. All simulations were carried out in the isothermal-isobaric (NPT) ensemble at 1 bar pressure and varying temperatures using approximately 4126 water molecules for TIP4P in a cubic simulation cell furnished with periodic boundary condition at different temperatures 280K ,298K, 318Kand 330K. Nanosecond trajectories were calculated with water model for high statistical accuracy. We compare properties of the pure PNIPAM oligomers of different lengths and block copolymer of poly(NIPAAm-b-TMC) such as the self-diffusion coefficients D, radius of gyration, radial distribution function, intermolecular hydrogen bonding and VMD snapshots to determine the drug releasing profile and differences in their structures and transition behavior. We also explore changes in polymer–polymer, polymer–water, polymer-drug interactions, including hydrogen bond formation.