title: Extracellular polymeric substances govern the surface charge of biogenic elemental selenium nanoparticles.
abstract: The origin of the organic layer covering colloidal biogenic elemental selenium nanoparticles (BioSeNPs) is not known, particularly in the case when they are synthesized by complex microbial communities. This study investigated the presence of extracellular polymeric substances (EPS) on BioSeNPs. The role of EPS in capping the extracellularly available BioSeNPs was also examined. Fourier transform infrared (FT-IR) spectroscopy and colorimetric measurements confirmed the presence of functional groups characteristic of proteins and carbohydrates on the BioSeNPs, suggesting the presence of EPS. Chemical synthesis of elemental selenium nanoparticles in the presence of EPS, extracted from selenite fed anaerobic granular sludge, yielded stable colloidal spherical selenium nanoparticles. Furthermore, extracted EPS, BioSeNPs, and chemically synthesized EPS-capped selenium nanoparticles had similar surface properties, as shown by ζ-potential versus pH profiles and isoelectric point measurements. This study shows that the EPS of anaerobic granular sludge form the organic layer present on the BioSeNPs synthesized by these granules. The EPS also govern the surface charge of these BioSeNPs, thereby contributing to their colloidal properties, hence affecting their fate in the environment and the efficiency of bioremediation technologies.
authors.affiliation: UNESCO-IHE, Institute for Water Education , Westvest 7, 2611AX Delft, The Netherlands.
authors.forename: Rohan
authors.initials: R
authors.lastname: Jain
authors.forename: Norbert
authors.initials: N
authors.lastname: Jordan
authors.forename: Stephan
authors.initials: S
authors.lastname: Weiss
authors.forename: Harald
authors.initials: H
authors.lastname: Foerstendorf
authors.forename: Karsten
authors.initials: K
authors.lastname: Heim
authors.forename: Rohit
authors.initials: R
authors.lastname: Kacker
authors.forename: René
authors.initials: R
authors.lastname: Hübner
authors.forename: Herman
authors.initials: H
authors.lastname: Kramer
authors.forename: Eric D
authors.initials: ED
authors.lastname: van Hullebusch
authors.forename: François
authors.initials: F
authors.lastname: Farges
authors.forename: Piet N L
authors.initials: PN
authors.lastname: Lens
mesh_terms: D001673:Biodegradation, Environmental; D002241:Carbohydrates / Q000032:analysis; D005110:Extracellular Space / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D053758:Nanoparticles / Q000737:chemistry* / Q000382:microbiology; D011108:Polymers / Q000032:analysis / Q000737:chemistry*; D011506:Proteins / Q000032:analysis; D012643:Selenium / Q000737:chemistry*; D012722:Sewage / Q000737:chemistry / Q000382:microbiology; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties
chemical_list: D002241:Carbohydrates; D011108:Polymers; D011506:Proteins; D012722:Sewage; D012643:Selenium