Novel gold nanoparticle-protein-semiconductor quantum dot hybrid system: synthesis, characterization and application in cancer cell imaging

Formation of a hybrid system by metallic nanoparticle, protein (or peptide), and a semiconductor QD can be a new and alternate material which may be used for biological applications including cancer cell detection and treatment. Herein, we report on the colloidal synthesis of metal-protein-QD hybrid system considering Au NPs, CdSe QDs, BSA and Lysozyme protein. We demonstrate the structural, optical and vibrational properties of Au-CdSe, Au-BSA-CdSe and Au-Lysozyme-CdSe hybrid systems following their use as cancer cell markers. The study of photoluminescence spectra reveals the predominance fluorescence resonance energy transfer (FRET) between CdSe QDs and Au NPs, Au-BSA and Au-Lysozyme complex. The energy transfer efficiency between QDs donor and the Au NPs, Au-BSA, Au-Lysozyme acceptors are estimated to be 46%, 94% and 64%; respectively. Fluorescence imaging results represent high biocompatibility and fluorescent behavior of the QDs and its hybrid system in the MDA-MB-231 breast cancer cells. The calculation of corrected total counts of fluorescence (CTCF) predicts the higher uptake of CdSe QDs as compared to the Au-QDs, Au-BSA-QDs, Au-Lysozyme-QDs by the cells. The significantly varied zeta potential values of the hybrid systems influence the cellular uptake processes. The fabrication of biocompatible (water soluble, biologically stable, having bioconjugation capability, low cytotoxic to the normal cells, fluorescent in biological environment) Au-CdSe, Au-protein-CdSe hybrid systems would open up an alternative strategy in nanobiotechnology, due to their special physical, optical as well as chemical properties.