Fluorescence Quenching of Aromatic Amino Acids by Rhodium Nanoparticles

In this paper, the fluorescence quenching of the aromatic amino acids tyrosine and tryptophan by rhodium nanoparticles has been investigated. The choice of rhodium nanoparticles was determined by the fact that the plasmonic maximum of the nanoparticles and the absorption range of the amino acids are in the UV. The quenching constants and types of quenching were estimated using Stern-Volmer dependencies. The fluorescence intensity of amino acids was found to decrease with nanoparticle concentration, with different types of quenching observed: tryptophan-nanoparticle system showed static quenching, while dual quenching (static and dynamic) occurred in tyrosine-nanoparticle system. Calculation of parameters of quenching efficiency were done: diffusion coefficient, diffusion rate parameter and quenching activation energy. Opportunities to exploit quenching mechanisms to realise optical sensing effects in UV have been shown.