Characterization and mechanism of metal selenides synthesized by Mariannaea sp. HJ

Abstract:

[Background] Metal selenides have attracted increasing attention in semiconductor, electrochemistry and anticancer fields due to its excellent photoelectric and catalytic properties. Compared with the traditional chemical methods, biosynthesis of metal selenides is environmentally friendly and lower energy. However, few studies on the biosynthesis of metal selenides were reported, and its relevant mechanisms were still unclear. [Objective] We chose Mariannaea sp. HJ to synthesize three kinds of metal selenides and proposed the possible mechanisms. [Methods] X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to initially characterize the metal selenides synthesized by strain HJ. The changes in total sulfhydryl content, total antioxidant capacity and free radical content were investigated during the synthesis process. Besides, the function of transporter DMT1 was also verified in the synthesis of metal selenides. [Results] XRD results showed that Bi₄Se₃, PbSe and CoSe₂ nanoparticles could be separately biosynthesized by strain HJ under the action of Bi³⁺, Pb²⁺, Co²⁺ and SeO₃^2-, and the optimal pH conditions for their synthesis were 6.0, 7.0, and 8.0, respectively. FTIR analysis illustrated that these nanoparticles were covered with certain functional groups such as amino, carboxyl and hydroxyl groups. Compared to the control group, it was also found that the total sulfhydryl concentration was significantly reduced during the synthesis process, while the total antioxidant performance was increased. It was indicated that the sulfhydryl system or the non-enzymatic system of amino acid metalloproteins could be involved in the reduction of SeO₃^2-. The benzylisothioureas shielding experiment showed that metal transporter DMT1 played a key role in SeO₃^2- transportation and metal selenides secretion. Besides, oxidative stress was produced after the addition of Bi³⁺, Pb²⁺and Co²⁺, which caused strain HJ to secrete more hydrogen peroxide, hydroxyl free radicals and superoxide free radicals outside the cells. The transportation process of metal ions or nanoparticles could be enhanced by above free radicals through inducing heat shock effects. [Conclusion] Mariannaea sp. HJ could greenly synthesize Bi₄Se₃, PbSe and CoSe₂ nanoparticles. This study would provide useful information for biosynthesis and mechanism of metal selenides.