title: Time-dependent growth of crystalline Au(0)-nanoparticles in cyanobacteria as self-reproducing bioreactors: 2. Anabaena cylindrica.
abstract: Microbial biosynthesis of metal nanoparticles as needed in catalysis has shown its theoretical ability as an extremely environmentally friendly production method in the last few years, even though the separation of the nanoparticles is challenging. Biosynthesis, summing up biosorption and bioreduction of diluted metal ions to zero valent metals, is especially ecofriendly, when the bioreactor itself is harmless and needs no further harmful reagents. The cyanobacterium Anabaena cylindrica (SAG 1403.2) is able to form crystalline Au(0)-nanoparticles from Au(3+) ions and does not release toxic anatoxin-a. X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and laser-induced breakdown spectroscopy (LIBS) are applied to monitor the time-dependent development of gold nanoparticles for up to 40 hours. Some vegetative cells (VC) are filled with nanoparticles within minutes, while the extracellular polymeric substances (EPS) of vegetative cells and the heterocyst polysaccharide layer (HEP) are the regions, where the first nanoparticles are detected on most other cells. The uptake of gold starts immediately after incubation and within four hours the average size remains constant around 10 nm. Analyzing the TEM images with an image processing program reveals a wide distribution for the diameter of the nanoparticles at all times and in all regions of the cyanobacteria. Finally, the nanoparticle concentration in vegetative cells of Anabaena cylindrica is about 50% higher than in heterocysts (HC). These nanoparticles are found to be located along the thylakoid membranes.
authors.affiliation: Universität Koblenz-Landau, Institut für Integrierte Naturwissenschaften, Abteilung Physik, 56070 Koblenz, Germany.
authors.forename: Liz M
authors.initials: LM
authors.lastname: Rösken
authors.affiliation: Universität Koblenz-Landau, Institut für Integrierte Naturwissenschaften, Abteilung Physik, 56070 Koblenz, Germany.
authors.forename: Felix
authors.initials: F
authors.lastname: Cappel
authors.affiliation: Universität Koblenz-Landau, Institut für Integrierte Naturwissenschaften, Abteilung Physik, 56070 Koblenz, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Körsten
authors.affiliation: Universität Koblenz-Landau, Institut für Integrierte Naturwissenschaften, Abteilung Physik, 56070 Koblenz, Germany.
authors.forename: Christian B
authors.initials: CB
authors.lastname: Fischer
authors.affiliation: Universität Bayreuth, Lehrstuhl für Kristallographie, 95440 Bayreuth, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schönleber
authors.affiliation: Universität Bayreuth, Lehrstuhl für Kristallographie, 95440 Bayreuth, Germany.
authors.forename: Sander
authors.initials: S
authors.lastname: van Smaalen
authors.affiliation: Universität Bayreuth, Zellbiologie / Elektronenmikroskopie, 95440 Bayreuth, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Geimer
authors.affiliation: Hochschule Koblenz, RheinAhrCampus Remagen, Optics and Laser Engineering, 53424 Remagen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Beresko
authors.affiliation: Hochschule Koblenz, RheinAhrCampus Remagen, Optics and Laser Engineering, 53424 Remagen, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Ankerhold
authors.affiliation: Universität Koblenz-Landau, Institut für Integrierte Naturwissenschaften, Abteilung Physik, 56070 Koblenz, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Wehner
keywords: X-ray powder diffraction (XRD); biosynthesis; gold nanoparticles; laser-induced breakdown spectroscopy (LIBS); transmission electron microscopy (TEM)