Experimental and computational study of the adsorption of 8-methoxypsoralen on gold and silver nanoparticle

Psoralens belong to a class of chemical compounds called furanocoumarins that consist of the fusion of coumarin to a furan ring. As a result of their optical properties, these molecules have important applications, for example, in the treatment of psoriasis and in skin cancer therapy. We believe that psoralens are good candidates in future applications of nanoplasmonics in the treatment of several skin diseases. Therefore, understanding the interactions of these molecules with the surface of the metal nanoparticles is crucial.

In this work we are studying the interaction of 8-methoxypsoralen (8MOP) with silver and gold nanoparticles by using Surface-enhanced Raman scattering (SERS). To get insights about the adsorption mechanisms of 8MOP on the nanoparticle surface we have implemented a multi-scale methodology combining all-atom molecular dynamics simulation with Density Functional Theory (DFT) calculations. With this approach we aim to obtain the atomic groups of 8MOP that directly interact with the metal atoms as well as the structural configuration with respect to the nanoparticle surface. Furthermore, we also observe that the pyron ring of 8MOP is cleaved under alkaline pH conditions, and the new molecule (Isomer Z) undergoes photoisomerization when exposed to UV light converting in the called Isomer E. We have studied the spectroscopic characteristics of these isomers by conducting absorption, fluorescence and SERS experiments in combination with DFT calculations. In this presentation, I will discuss the results of our experimental and computational study, highlighting the spectroscopic characteristics, adsorption mechanisms and structural interactions of 8MOP and its isomers with metal nanoparticles.