Controlled shell on nanoparticles as a tool to regulate the properties of immobilized molecules

Tuning functions of organic molecules is a remaining challenge in versatile applications. Here, we demonstrated the pKa of 11- mercaptoundecanoic acid can be subtly tuned by the gold shell thickness of Fe₂O₃@Au core-shell nanoparticles. Based on titration results, the rebalance of the electrostatic and vdW interactions on nanoparticles was proposed as a mechanism for regulating the pKa of 11-mercaptoundecanoic acid on nanoparticles. Further, the simulation by DLVO theory validated our mechanism, and thus offering a potential route to tune the functions of organic molecules.