Spectroscopic Investigation of Interaction Between Carbon Quantum Dots and D-Penicillamine Capped Gold Nanoparticles

This study reports the interaction and energy transfer between fluorescent carbon quantum dots (CQDs) and D-Penicillamine capped gold nanoparticles (DPA-AuNPs). The CQDs was synthesized by a simple chemical oxidation method at room temperature. The prepared CQDs shows a strong fluorescence at lambda (em) = 430 nm when excited at lambda (ex) = 320 nm. The interaction of CQDs with DPA-AuNPs was characterized by fluorescence spectroscopy, Transmission Electron Microscopy (TEM) study and Dynamic Light Scattering (DLS) techniques. The fluorescence study shows the continuous quenching in the fluorescence intensity of CQDs in presence of increasing concentrations of DPA-AuNPs. The change in fluorescence spectra of CQDs in presence of increasing concentration of DPA-AuNPs and quenching are suggestive of a rapid adsorption of CQDs on the surface of DPA-AuNPs. The K (sv) , K, K (q) and n values were calculated and results indicated that the dynamic type of quenching takes place. The distance between donor and acceptor (r) is 6.07 nm which supports the energy transfer by Fluorescence Resonance Energy Transfer (FRET) phenomenon. The plausible mechanism for FRET is also discussed.