Cadmium chalcogenide derived fluorescent quanta-sensor for melamine detection

The present work reports the detection of melamine (artificial protein) in milk using mercapto-propionic acid capped cadmium selenide (m-CdSe) quantum dots (QDs) as fluorescent labels, denoted as quanta-sensor. The m-CdSe QDs were prepared using aqueous chemical synthesis method and were characterized to get insight about their structural and functional properties. The formation of m-CdSe QDs was confirmed by using Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The optical properties (absorption and emission) of m-CdSe QDs were studied as a function of cadmium salt concentration, selenide salt concentration and pH. The effect of incubation time with melamine on fluorescence of QDs was also studied in order to check the stability of quanta-sensor. The linearity range of this quanta-sensor was found to be 0.01 nM to 60 mu M, with LOD of 0.013 nM. The quanta sensor exhibited good reproducibility, selectivity and acted as a potential probe for detection of melamine in milk samples.