Physico-chemical analysis of molecular binding to the colloidal metal nanostructure: Multiple micro- and nanospectroscopy study

The work presents a detailed analysis of adsorption geometry of nocodazole, an antineoplastic agent, deposited onto gold nanoparticle surface. This type of study is fundamental because of improving drugs delivery specifically to cancer cells. Simultaneously, it will revolutionize oncology, dramatically improving the effect of drugs while reducing or even eliminating adverse side effects for the patient. The analytical means are now mature to study very precisely the solid-liquid interactions that will foreshadow the development of new anti-cancer therapies. This research demonstrates the feasibility of surface-enhanced infrared absorption spectroscopy (SEIRA), surface-enhanced Raman spectroscopy (SERS) and polarization-modulated surface-enhanced infrared absorption nanospectroscopy (PM-SEIRA) to study adsorption phenomenon of a molecule at the solid/liquid interface. A novel approach combining the classical infrared spectroscopy (IR) with atomic force microscopy (AFM) is employed to more comprehensively describe the behavior of the drug adsorbed on metal surface at the nanoscale level. The performed analysis enabled to track subtle changes in nocodazole bonds arrangement upon adsorption. The observed changes provide evidence for strong interaction between the electron-rich thiophene ring and metal surface. It can also be inferred that charge-transfer mechanism contributes considerably to the SERS signal amplification.