Adsorption of Protein on a Au Surface Studied by All-Atom Atomistic Simulations

AR Wei and C Deng, JOURNAL OF PHYSICAL CHEMISTRY C, 120, 13103-13112 (2016).

DOI: 10.1021/acs.jpcc.6b03523

In this work, the adsorption of protein on a Au surface coated by self- assembled monolayers (SAMs) of alkanethiol chains is studied by molecular dynamics simulations with an all-atom model. Particularly, a more realistic embedded-atom method potential has been used to characterize the Au-Au interactions in the system as compared to previous studies. With this all-atom model, many experimental observations have been reproduced from the simulations. It is found that the SAMs have the lowest adsorption energy on the Au(111) surface where the alkanethiol chains form a well ordered (root 3x root 3)R30 degrees triangular lattice at 300 K. Furthermore, it is confirmed that carboxyl- terminated SAMs are more effective to absorb proteins than the methyl- terminated SAMs. On the basis of the simulation results, we propose that the experimentally observed aggregation of protein-Au nanoparticle conjugates is mainly due to the electrostatic interactions between protein amino acids and carboxyl-terminated SAMs from multiple Au surfaces.

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