Unlocking on the effect of gold cluster with pregabalin, a bioactive molecule: Solvation, SERS and reactivity analysis

The interaction of pregabalin ((S)-3-(Aminoethyl)-5-methylhexanoic acid) (PGB) with Au₄ clusters at various positions is studied computationally investigated and reported. Adsorption processes are exothermic which is beneficial for drug delivery applications. PGB is interacted with Au₄ through its OH (X1), CO (X2), NH₂ (X3) and CH₃ (X4) according to MEP analysis and the adsorption energies are, −6.27/-26.06/-39.74/-4.21 in vacuum and −16.16/-35.36/-53.22/-15.49 kcal/mol in aqueous medium. The appearance of new bands in PGB-Au₄ complexes is due to surface enhanced Raman spectroscopy (SERS effect). For X2 and X3 configurations with maximal adsorption energies, strong interaction is shown with the Au₄ and these adsorptions can be categorized as chemisorptions since adsorption energies are larger than −23.0 kcal/mol, while X1 and X4 have a physisorption adsorption process since adsorption energy is less than −23.0 kcal/mol. All Au₄-PGB systems have electrophilicity indices greater than the PGB value, implying that adding of gold clusters makes pharmaceuticals more electrophilic. As the energy gaps close, the cluster's conductivity increases making it suitable for use as a drug sensor. Solvents have higher negative solvation energies, indicating that the solvent medium is more stable. The presence of NCI is confirmed using interaction analysis. ELF analysis reveals that Au₄ cluster forms an ionic bond with the PGB surface. Drug carrier activity is evident from the docking scores.