Conductance Switching in Single-Peptide Molecules through Interferer Binding

Detection of bioprocess-interfering metal ions and molecules is important for healthcare, and peptide single-molecule junctions have shown their potential toward sensing these targets efficiently. Using first-principles calculations, we investigate the conductance of Cys-Gly-Cys and cysteamine-Gly-Gly-Cys peptide junctions, and the effect of its change upon copper-ion (Cu²⁺) or bisphenol A (BPA) binding. The calculated conductance of the peptides and the Cu²⁺-peptide complexes agrees well with the experimental data and that of the BPA-bond peptides is further predicted. Our analyses show that the conductance switching mainly comes from the structure deformation of the peptide caused by Cu²⁺ binding or from the new conduction channel added by BPA binding. Our results suggest that the cysteamine-Gly-Gly-Cys junction can recognize Cu²⁺ and BPA better than the Cys-Gly-Cys one does.