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

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 (√3×√3)R30° 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.