Green synthesis of well-defined spherical PbS quantum dots and its potential in biomedical imaging research and biosensing

In this research, we present a facile, effective and green route for the synthesis of well-defined spherical lead sulfide (PbS) quantum dots (QDs) through the reaction between lead nitrate and sodium sulphide by virtue of its strong reduction and selective interaction abilities without using any surfactant, and evaluate its potential for use in biomedical imaging and biosensing applications. The average crystallite size using Scherrer´s formula was about 13 nm and the calculated lattice constant using Bragg´s equation was 0.5950 nm, which was very close to the value in the standard card JCPDS file No. 5-592, and the crystal structure of PbS QDs was in its cubic phase. The synthesized particles had well-defined spherical morphology, and the photoluminescence (PL) study showed that the emission spectrum was a strong and narrow band with high intensity which confirmed the high-quality luminescence properties of the prepared PbS QDs. A possible formation mechanism of the PbS QDs and its Potential in Biomedical Imaging Research and Biosensing has also been put forward and discussed.