title: Synthesis and characterization of biomatrixed-gold nanoparticles by the mushroom Flammulina velutipes and its heterogeneous catalytic potential.
abstract: Sustainable and greener synthesis of intracellular gold nanoparticles using mushroom Flammulina velutipes is reported. Incubation of a mushroom in chloroaurate solution resulted in the synthesis and immobilization of stable gold nanoparticles inside the mushroom mycelia. Transmission electron microscopic (TEM) analysis revealed the presence of gold nanoparticles (⩽20nm) inside the mycelia, primarily on the inner surface of the cell membrane. Inductively coupled plasma-optical emission spectrometry (ICP-OES) revealed that the accumulated gold concentration ranged from 64.4 to 330.5mgkg(-1) dry weight (DW) in the mushroom mycelia. The reduction of Au(3+) ions to Au(0) and stabilization of gold nanoparticles occurred within 1h, and the formation of fcc crystalline gold nanoparticles was confirmed by X-ray diffraction (XRD) analysis. This facile intracellular synthesis of gold nanoparticles by a mushroom without using any toxic chemicals or technologically expensive processes is used as a heterogeneous catalyst in the reduction of organic pollutants methylene blue (MB) and 4-nitrophenol (4NP). The reduction reaction follows pseudo-first order kinetics with a reaction rate constant of 0.0529min(-1) and 0.1236min(-1) for MB and 4NP, respectively. This biological process of biomatrixing of metal nanoparticles for heterogeneous catalytic reactions is simple, nontoxic, environmentally benign, and economically viable compared to the chemical synthetic routes.
authors.affiliation: Department of Chemical Engineering, College of Engineering, Yeungnam University, Gyeongsan 712-749, South Korea; Polymer Gel Cluster Research Center, Yeungnam University, Gyeongbuk 712-749, South Korea; School of Biotechnology and Graduate School of Biochemistry, Yeungnam University, Gyeongsan 712-749, South Korea.
authors.forename: Kannan Badri
authors.initials: KB
authors.lastname: Narayanan
authors.affiliation: School of Biotechnology and Graduate School of Biochemistry, Yeungnam University, Gyeongsan 712-749, South Korea. Electronic address: hyunho@ynu.ac.kr.
authors.forename: Hyun Ho
authors.initials: HH
authors.lastname: Park
authors.affiliation: Department of Chemical Engineering, College of Engineering, Yeungnam University, Gyeongsan 712-749, South Korea; Polymer Gel Cluster Research Center, Yeungnam University, Gyeongbuk 712-749, South Korea. Electronic address: sshan@yu.ac.kr.
authors.forename: Sung Soo
authors.initials: SS
authors.lastname: Han
mesh_terms: D002384:Catalysis; D004785:Environmental Pollutants / Q000032:analysis; D055393:Flammulina / Q000254:growth & development* / Q000378:metabolism; D006046:Gold / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D053768:Metal Nanoparticles / Q000737:chemistry*; D008751:Methylene Blue / Q000032:analysis; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D025282:Mycelium / Q000737:chemistry / Q000378:metabolism; D009596:Nitrophenols / Q000032:analysis; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D004785:Environmental Pollutants; D009596:Nitrophenols; D006046:Gold; D008751:Methylene Blue; C024836:4-nitrophenol
keywords: Au(3+) ions; Gold nanoparticles; In vivo; Mushroom; Pseudo-first order reaction; Transmission electron microscopy