Investigating the substitution of intermolecular hydrogen bonds on the surface of self-assembled monolayer by scanning electrochemical microscopy

Investigating the substitution of intermolecular hydrogen bonds on the simulated biofilm surface at molecular level is beneficial to understand the mechanism of molecular selective recognition occurring on biofilm surface. In this paper, the substitution of intermolecular hydrogen bonds on the surface of simulated biofilm, self-assembled monolayer of 3-mercaptopropionic acid (MPA SAM), is studied using scanning electrochemical microscopy (SECM). When acetic acid exists on MPA SAM surface, the intermolecular hydrogen bonds between acetic acid and MPA SAM are able to replace those between the redox mediator ferrocenemethanol (FcCH₂OH) and MPA SAM, because the stronger charge-assisted hydrogen bonds (CAHB) formed between acetic acid and MPA SAM have the ability of substitution. The effect of the substitution of intermolecular hydrogen bonds is more significant with increasing the concentration of acetic acid within certain limits. This work may provide ideas for deeper understanding of molecular selective recognition on biofilm surface.