Synthesis and characterization of Mn-Doped ZnO quantum dots utilizable in optical biosensors

The ZnO quantum dots (QDs) were successfully synthesized via co-precipitation technique and the effect of Mn2+ ions concentration as dopant on the optical properties was studied. To control the particle size by limiting the growth of the particles after the nucleation and to provide a side group on surface which can be further conjugated to bio-cell using polyethylene glycol (PEG) as bio-compatible capping agent. XRD analyses revealed single phase ZnO wurtzite crystal structure. TEM micrograph illustrates that the final QDs were about 10-30 nm in diameter with spherical shape. Also, the organic groups on the surface of nano-particles (NPs) were characterized by Fourier transform infrared spectroscopy (FTIR). From photoluminescence spectra, besides emission peak at 356 nm related to ZnO, doping Mn2+ ions in the host lattice led to appearance of the new visible emission band in the range of 410-450 nm because of 4T1→6A1 transition. Results show that the final QDs have potential for biochemical optical sensing.