Plasmon-mediated N-dealkylation instead chiral discrimination of propranolol drug adsorbed on gold nanoparticles

Abstract

Detailed knowledge and a deep understanding of the surface processes occurring on plasmonic substrates under a local electromagnetic field are essential for further research and development of their applications. This is especially relevant for the interface phenomena involving gold nanoparticles and bioactive molecules since such systems may be intended for living cells or the human body. Here, the comprehensive study of beta-blockers adsorption (propranolol, carvedilol, and amlodipine) on bare and modified gold nanoparticles is presented. Surface-enhanced Raman scattering and capillary electrophoresis were used to study gold surface and solution above at different duration of drugs adsorption. It was found that N-dealkylation occurs with propranolol molecules adsorbed on the uncoated gold nanoparticles and the reaction product was confirmed by high performance liquid chromatography coupled with high resolution mass spectrometry. The study of propranolol adsorption under argon bubbling and in the presence of a singlet oxygen scavenger established a key oxidative role of reactive oxygen species promoted by gold nanoparticles. The mechanism of propranolol surface N-dealkylation is proposed based on comprehensive experimental and literature data analysis. The revealed plasmon-assisted reaction may have important implications for further use of gold nanoparticles in bioanalysis and medicine.