Multiscale Computer Simulation On The Smart Responsive Gold Nanoparticles

Multiscale simulation methods, including coarse-grained molecular dynamics (CGMD)and dissipative particle dynamics (DPD), are adopted to investigate the structure-propertyrelationships of a series of smart responsive gold nanoparticles (AuNPs) and nanomaterialsurfaces.Firstly, polystyrene (PS) and polyoxyethylene (PEO) block/mixed polymer brushmodified gold nanoparticles are studied via CGMD based on Martini force field; responsivemorphologies, particle size and surface chemistry are investigated. From these results, we canconclude that, AuNPs mainly form core-shell structure in different solvents. However,specific block sequence, mixing mode and solvent quality will make nanoparticles exhibitinteresting shaped morphologies, such as buckle-like, ring-like, jellyfish-like, octopus-likeand so on.Then, again using the Martini force field based CGMD method, we systematicallyexplore the oil-water interface behavior and phase transfer behavior of model triblockamphiphilic polymer brush modified AuNPs. The simulation results indicates that the phasetransfer could happen if only the hydrophobic blocks act as the head and tail block, and thecontent of weak hydrophilic blocks in the middle is lower than60%. Oppositely, when stronghydrophilic blocks are included in the brushes, AuNPs would be always restricted in theinterfacial zone and radially spread in a shape we call "flat Janus". Also, the influences ofthree blocks on interfacial behavior and phase transfer capacity are quite different.We use DPD method to simulate the PS and poly(N-isopropylacrylamide)(PNIPAM)block/mixed polymer brush grafted AuNPs, of which the temperature and solvent dualresponsiveness on the self-assembly morphologies in water, chloroform and mixed solventswith different water-oil ratio is investigated. According to our simulation results, theself-assembly aggregation morphologies can be divided into7categories according to theaggregation extent from high (spherical aggregation) to low (dissolved). The formationmechanisms of7self-assembly morphologies and unique "oil in water" and "water in oil"structures existing in mixed solvents are detailedly discussed and interpreted from amicroscopic view.Finally, pH responsive poly (-amino ester)(PAE)/PEO block polymer brush modifiedgold nanoparticles as anticancer drug carrier are simulated with DPD method. We can findfrom simulation results that the anticancer drug carriers formed by polymer brush modified AuNPs have obvious advantages over the carriers formed by the self assembly of polymerchains under the same composition. PAE-b-PEO-b-PAE modified AuNPs have enhanced pHresponsiveness on particle size, compared with PAE-b-PEO modified AuNPs. Also, the pHresponsiveness of surface chemistry is observed by PAE-b-PEO-b-PAE modified AuNPs. Theoptimal block ratio for two kinds of brush modified AuNP systems are obtained, respectively.