Micro-Emulsion Synthesis, Surface Modification, and Photophysical Properties of ${\rm Zn}_{1-x}~{\rm Mn}_{\rm x} {\rm S}$ Nanocrystals for Biomolecular Recognition

In this research, we mainly focused on the micro-emulsion synthesis of biotinylated ZnS (zinc sulfide) nanocrystals for avidin recognition. Various samples of Zn_1-xMn_x S, with x = 0.0001, 0.007, 0.02, 0.03, 0.055, 0.09 and 0.13, prepared by quaternary W/O (water-in-oil) microemulsion system. Cyclohexane was used as oil, Triton X-100 as surfactant, n-hexanol as a co-surfactant and mercaptoethanol and thioglycolic acid as linking agents. The obtained products were evaluated by commonly techniques such as: scanning electron microscopy (SEM), transmission electron microscopy (TEM), zeta meter for measurement ZP (zeta potential) and fluorescence spectroscopy analyses. The above-experimental results indicated that the optimum doping concentration of Mn was ~ 5.5% . The fluorescence spectra of the doped crystals consist of orange-red emissions. Eventually, this research showed with increasing more than 18 μl biotin to nanocrystals, no changes were observed in the emission intensity spectra.