title: Metal sulfide nanoparticles synthesized via enzyme treatment of biopolymer stabilized nanosuspensions.
abstract: Nanoparticles of CuS, Cu(x)S, Ag(2)S and CdS were successfully prepared using a novel general and green synthetic process to give dextran biopolymer stabilised metal sulfifde nanosuspensions. Following preparation, dextranase enzyme was used to remove the bulk of the bound dextran to give pure stable metal sulfide nanocrystals for application in for example aspects of medicine, photonics and solar cells. Particles of good homogeneity were obtained and the CuS nanoparticle size was controlled to 9-27 nm by adjusting the reaction conditions. Cu(2)S nanoparticles were 14 nm, Ag(2)S nanoparticles were 20-50 nm and CdS nanoparticles were 9 nm is size. The complexing mechanism of nanoparticle sulfides to dextrans was further studied using carboxylmethyl dextran as a complexing agent and crosslinked Sephadex (dextran) ;beads as substrate. Particles were characterized by TEM, XRD, TGA, FT-IR and zeta-potential measurement, and their UV-vis spectroscopic absorption properties were determined. Stabilization of the sulfide nanoparticles with soluble hydroxylated biopolymers such as dextran is previously unreported and is here interpreted in terms of viscosity, pH of the system and weak polar S-H or S(metal)OH(2)(+) interactions with dextran depending on the material. Notably, the complexing mechanism appears to differ significantly from that taking place in known dextran-metal oxide systems. The process shown here has good potential for scale-up as a biosynthetic route for a range of functional sulfide nanoparticles.
authors.affiliation: School of Chemistry, University of Leeds, Leeds, LS2 9JT, UK.
authors.forename: Yi-Yeoun
authors.initials: YY
authors.lastname: Kim
authors.forename: Dominic
authors.initials: D
authors.lastname: Walsh
mesh_terms: D001704:Biopolymers / Q000737:chemistry*; D019187:Cadmium Compounds / Q000737:chemistry; D003300:Copper / Q000737:chemistry; D003911:Dextrans / Q000737:chemistry; D004798:Enzymes / Q000378:metabolism*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008670:Metals / Q000737:chemistry*; D018030:Silver Compounds / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013440:Sulfides / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D001704:Biopolymers; D019187:Cadmium Compounds; D003911:Dextrans; D004798:Enzymes; D008670:Metals; D018030:Silver Compounds; D013440:Sulfides; C034939:cadmium sulfide; D003300:Copper; C013251:silver sulfide; C017846:cupric sulfide