title: Detecting and Number Counting of Single Engineered Nanoparticles by Digital Particle Polymerase Chain Reaction.
abstract: The concentrations of nanoparticles present in colloidal dispersions are usually measured and given in mass concentration (e.g. mg/mL), and number concentrations can only be obtained by making assumptions about nanoparticle size and morphology. Additionally traditional nanoparticle concentration measures are not very sensitive, and only the presence/absence of millions/billions of particles occurring together can be obtained. Here, we describe a method, which not only intrinsically results in number concentrations, but is also sensitive enough to count individual nanoparticles, one by one. To make this possible, the sensitivity of the polymerase chain reaction (PCR) was combined with a binary (=0/1, yes/no) measurement arrangement, binomial statistics and DNA comprising monodisperse silica nanoparticles. With this method, individual tagged particles in the range of 60-250 nm could be detected and counted in drinking water in absolute number, utilizing a standard qPCR device within 1.5 h of measurement time. For comparison, the method was validated with single particle inductively coupled plasma mass spectrometry (sp-ICPMS).
authors.affiliation: Institute for Chemical and Bioengineering, ETH Zurich , Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland.
authors.forename: Daniela
authors.initials: D
authors.lastname: Paunescu
authors.affiliation: Institute for Chemical and Bioengineering, ETH Zurich , Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Mora
authors.affiliation: Laboratory of Inorganic Chemistry, ETH Zurich , Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Querci
authors.affiliation: IBM Research , Säumerstrasse 4, 8803 Rüschlikon, Switzerland.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Heckel
authors.affiliation: Institute for Chemical and Bioengineering, ETH Zurich , Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland.
authors.forename: Michela
authors.initials: M
authors.lastname: Puddu
authors.affiliation: Laboratory of Inorganic Chemistry, ETH Zurich , Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland.
authors.forename: Bodo
authors.initials: B
authors.lastname: Hattendorf
authors.affiliation: Laboratory of Inorganic Chemistry, ETH Zurich , Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland.
authors.forename: Detlef
authors.initials: D
authors.lastname: Günther
authors.affiliation: Institute for Chemical and Bioengineering, ETH Zurich , Vladimir-Prelog-Weg 1, 8093 Zurich, Switzerland.
authors.forename: Robert N
authors.initials: RN
authors.lastname: Grass
mesh_terms: D004247:DNA / Q000032:analysis*; D060766:Drinking Water / Q000032:analysis*; D004784:Environmental Monitoring / Q000295:instrumentation; D004867:Equipment Design; D053758:Nanoparticles / Q000032:analysis* / Q000648:ultrastructure; D010316:Particle Size; D044367:Phase Transition; D016133:Polymerase Chain Reaction / Q000295:instrumentation*; D012822:Silicon Dioxide / Q000032:analysis*
chemical_list: D060766:Drinking Water; D012822:Silicon Dioxide; D004247:DNA
keywords: DNA; digital PCR; encapsulation; particle analytics; silica; sol−gel processes