Adsorption and sensing of vildagliptin on coinage metal nanoclusters: DFT, MD and spectroscopic insights

This work presents a focused computational investigation of how the anti-diabetic drug vildagliptin (VGP) interacts with small coinage-metal clusters (Ag3, Au3 and Cu3) and the implications of those interactions for sensing and nanoscale delivery. Adsorption is exothermic for all metal-drug combinations, with adsorption energies in vacuum roughly spanning −15.7 to −33.5 kcal mol−1 (Ag3 ≈ −15.7 to −21.4; Au3 ≈ −21.3 to −33.5; Cu3 ≈ −25.3 to −31.5), and stronger binding in water (largest for the NH-site complexes, e.g., Au3-VGP3 ≈ −52.7 kcal mol−1). The energy-gap decreases (∆Eg) and DOS changes indicate increased conductivity upon adsorption – a desirable feature for electrochemical sensing – while computed Raman/IR shifts and SERS-relevant enhancements support spectroscopic detectability. MD and docking show that VGP and Au3-complexes tend to preserve protein structural stability, whereas Ag3 and especially Cu3 complexes can induce greater conformational perturbation.