Biomineralization Based Biosynthesis And Characterization Of CdS Nanoparticles With Its Applications

Major shortcomings of nanoparticles synthesized via the current physicochemical approaches are increasingly recognized,they are toxic,high nenergy consumption,in addition to decreasing biological accessibility of nanoparticles.With the development of bio-nanotechnology,the exploration of novel,clean and simple procedures using environmental-friendly biological materials for the synthesis of CdS nanoparticles are highly expected.Recently,for the first time,chemical-prepared calcium carbonate was applied successfully for the synthesis of Au and Ag nanoparticles as supporters and coating agents.Calcium carbonate has been found as a perfect adjuvant for nanoparticle synthesis.Thus,bacterial metabolism such as microbially induced calcite precipitation(MICP)could be very effective in nanoparticle synthesis.However,there is no report on MICP process for the biosynthesis of CdS nanoparticlesIn the present research,we demonstrated a novel and reliabe biosynthesis method for the preparation of monodispersed CdS nanoparticles supported by biocalcite through MICP.The approach is safe,low cost and more convenient without requiring any addiaional stabilizer,special instrumentation or poisonous intermediate.Further,the application of biosynthesized CdS nanoparticles in photocatalytic disinfection towards E.coli and nickel remediation in soil has been studied.The results showed that:(1)Abundant monodispersed CdS nanoparticles was harvested in MICP media combined with biocalcite.The fluorescence spectra and UV-vis absorption spectra indicated the CdS nanoparticles synthesized through MICP owns smaller particle size and improved quantum yields compared with hydrothermal CdS nanoparticles(2)XRD analysis confirmed the formation of CdS nanoparticles in the surface of biocalcite minerals in the precipitation.FTIR measurement demonstrated the chemical composition of as-prepared nanoparticles.The typical C-O and C-C stretching vibration suggested that the CaCO3.deposits are bounded with biosynthesized CdS nanoparticles.SEM and HRTEM micrographs showed that the particle size were in the range of 50-100 nm and the morphology of CdS products were roughly spherical.(3)In the application experiment,almost 60%of E.coli cells was killed in biocalcite-CdS nanoparticles supplemented media,indicating the superior antimicrobial ability of as-prepared nanoparticles;the Ni remediation experiment demonstrated the superior ability of biocalcite-CdS nanoparticles to remove heavy metals to negligible concentrations.This simple but efficient approach has open up a new angle of view for the biosynthesis nanoparticles through bacterial metabolic activity.Here,microbially induced calcite precipitation has been proven to enhance the formation of CdS nanoparticles and provide CdS nanoparticles with superior dispersibility,fluorescent and biocompatible properties.