Restrained molecular dynamics simulations were performed to study the binding affinity of the peptide with alkanethiols of different tail-groups, S(CH2)7CH3, S(CH2)7OH and S(CH2)7COOH, which self-assembled on Au(111)surface in the presence of water molecules. The curves of binding affinity were calculated by fixing the center of mass of the peptide at various distances from the assembling surface. Simulation results show that the binding affinity is in the order as COOH-SAMs>OH-SAMs>CH3-SAMs, while 100% COOH-SAMs>5% COOH-SAMs in concentration. The effects on binding affinity by different tail-groups were also studied. Results show that the binding affinity between COOH-SAMs and the peptide is bigger than those of the others and increasing the acidity of COOH-SAMs will result in stronger attractive power.
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