Biosynthesis of Lead Selenide (PbSe) Quantum Particles in Marine Fungus

Abstract

Lead selenide (PbSe) quantum particles (QPs), a typical semiconductor material of the IV–VI group are capturing the attention of material scientists for their shape controlled synthesis to utilize their excellent size tunable optical properties in diverse sectors. In order to address the disadvantages of the traditional chemical approach for PbSe QP synthesis, biosynthesis of these technologically relevant nano-fabrications was initiated in Pb and Se tolerant marine Aspergillus terreus. The formation of PbSe QPs were confirmed using TEM and SEM images that revealed the formation of rod like structures having an average diameter of 59 nm with an aspect ratio between 10 and 70. Detailed characterization to reveal the other structural and optical properties of the colloidal PbSe QPs were also carried out. The cyclic voltammogram of the biosynthesized PbSe QPs were characterized with five reaction peaks corresponding to the oxidation of PbSe, Se2O3 and Pb(OH)2 and the reduction of PbO2 and Pb(OH)2. Further, the statistical optimization of the process parameters during the biosynthesis of PbSe QPs for an enhanced fluorescence was carried out. It was observed that parameter optimization results in a florescence blue shift and a reduction in PbSe QP’s size to dimensions comparable to its excitonic Bohr radius (21nm). The fluorescence amenability of the biosynthesized PbSe QPs was utilized for the development of in-situ cadmium (II) sensing array. Initial experimental observations revealed sensitive and detectable quenching in fluorescence of the biogenic colloidal PbSe QPs in the presence of cadmium (II) ions in comparison to other tested metal ions. Subsequently advanced chromatographic and spectroscopic analyses confirmed the involvement of metal binding peptides namely metallothioneins, phytochelatins and superoxide dismutase that play a prominent role in the microbial metal detoxification system for the biosynthesis of PbSe QDs.