title: Reference materials and representative test materials to develop nanoparticle characterization methods: the NanoChOp project case.
abstract: This paper describes the production and characteristics of the nanoparticle test materials prepared for common use in the collaborative research project NanoChOp (Chemical and optical characterization of nanomaterials in biological systems), in casu suspensions of silica nanoparticles and CdSe/CdS/ZnS quantum dots (QDs). This paper is the first to illustrate how to assess whether nanoparticle test materials meet the requirements of a "reference material" (ISO Guide 30, 2015) or rather those of the recently defined category of "representative test material (RTM)" (ISO/TS 16195, 2013). The NanoChOp test materials were investigated with small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and centrifugal liquid sedimentation (CLS) to establish whether they complied with the required monomodal particle size distribution. The presence of impurities, aggregates, agglomerates, and viable microorganisms in the suspensions was investigated with DLS, CLS, optical and electron microscopy and via plating on nutrient agar. Suitability of surface functionalization was investigated with attenuated total reflection Fourier transform infrared spectrometry (ATR-FTIR) and via the capacity of the nanoparticles to be fluorescently labeled or to bind antibodies. Between-unit homogeneity and stability were investigated in terms of particle size and zeta potential. This paper shows that only based on the outcome of a detailed characterization process one can raise the status of a test material to RTM or reference material, and how this status depends on its intended use.
authors.affiliation: Institute for Reference Materials and Measurements, Joint Research Centre, European Commission Geel, Belgium.
authors.forename: Gert
authors.initials: G
authors.lastname: Roebben
authors.affiliation: Institute for Reference Materials and Measurements, Joint Research Centre, European Commission Geel, Belgium.
authors.forename: Vikram
authors.initials: V
authors.lastname: Kestens
authors.affiliation: Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences Budapest, Hungary.
authors.forename: Zoltan
authors.initials: Z
authors.lastname: Varga
authors.affiliation: Institute for Reference Materials and Measurements, Joint Research Centre, European Commission Geel, Belgium.
authors.forename: Jean
authors.initials: J
authors.lastname: Charoud-Got
authors.affiliation: Institute for Reference Materials and Measurements, Joint Research Centre, European Commission Geel, Belgium.
authors.forename: Yannic
authors.initials: Y
authors.lastname: Ramaye
authors.affiliation: Physikalisch-Technische Bundesanstalt Berlin, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Gollwitzer
authors.affiliation: LGC Limited Teddington, UK.
authors.forename: Dorota
authors.initials: D
authors.lastname: Bartczak
authors.affiliation: Biophotonics Division 1.10, Federal Institute for Materials Research and Testing Berlin, Germany.
authors.forename: Daniel
authors.initials: D
authors.lastname: Geißler
authors.affiliation: Analytical Sciences, National Physical Laboratory Teddington, UK.
authors.forename: James
authors.initials: J
authors.lastname: Noble
authors.affiliation: Institute for Reference Materials and Measurements, Joint Research Centre, European Commission Geel, Belgium.
authors.forename: Stephane
authors.initials: S
authors.lastname: Mazoua
authors.affiliation: Institute for Reference Materials and Measurements, Joint Research Centre, European Commission Geel, Belgium.
authors.forename: Nele
authors.initials: N
authors.lastname: Meeus
authors.affiliation: Institute for Reference Materials and Measurements, Joint Research Centre, European Commission Geel, Belgium.
authors.forename: Philippe
authors.initials: P
authors.lastname: Corbisier
authors.affiliation: Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences Budapest, Hungary.
authors.forename: Marcell
authors.initials: M
authors.lastname: Palmai
authors.affiliation: Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Hungarian Academy of Sciences Budapest, Hungary.
authors.forename: Judith
authors.initials: J
authors.lastname: Mihály
authors.affiliation: Physikalisch-Technische Bundesanstalt Berlin, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Krumrey
authors.affiliation: LGC Limited Teddington, UK.
authors.forename: Julie
authors.initials: J
authors.lastname: Davies
authors.affiliation: Biophotonics Division 1.10, Federal Institute for Materials Research and Testing Berlin, Germany.
authors.forename: Ute
authors.initials: U
authors.lastname: Resch-Genger
authors.affiliation: Analytical Sciences, National Physical Laboratory Teddington, UK.
authors.forename: Neelam
authors.initials: N
authors.lastname: Kumarswami
authors.affiliation: Analytical Sciences, National Physical Laboratory Teddington, UK.
authors.forename: Caterina
authors.initials: C
authors.lastname: Minelli
authors.affiliation: Analytical Sciences, National Physical Laboratory Teddington, UK.
authors.forename: Aneta
authors.initials: A
authors.lastname: Sikora
authors.affiliation: LGC Limited Teddington, UK.
authors.forename: Heidi
authors.initials: H
authors.lastname: Goenaga-Infante
keywords: analytical quality assurance; materials characterization; metrology; nanoparticle; reference material