Synthesis of the MPA- Capped CdSe/ZnS Quantum Dots and Study the Quenching Effect of Azo Dyes on Them

Quantum dots have received great attention for the past years as fluorescent markers for physical, chemical, and biological applications due to their unique size-dependent electrical and optical properties such as high extinction coefficient, broad absorption with narrow symmetric size-tunable fluorescent spectra, and strong resistance to photobleaching with significant luminescence quantum yield. In this study, at first the CdSe/ZnS quantum dots coated with oleylamine surface ligand were synthesized by high temperature injection method under vacuum conditions and stable nitrogen at 320°C. Then, in order to investigate the quenching effect of azo dyes, which is one of the most carcinogenic chemical colors used in various industries, on the emission of these nanoparticles, we used mercaptopropionic acid as a suitable hydrophilic ligand at the surface modification of quantum dots in the ligand exchange process as a proper aqueous phase transfer strategy. After confirming the proper synthesis of CdSe/ZnS nanoparticles by the transmission electron microscopy (TEM) test and the synthesized nanoparticle core and shell standard powder diffraction files (pdfs) in X-ray diffraction (XRD), the results of the studies showed that the methyl red due to its absorption spectrum overlapping with the emission spectrum of these quantum dots has a very powerful quenching effect on the emission of synthesized nanoparticles.