Distinguishing the sources of silica nanoparticles by dual isotopic fingerprinting and machine learning

One of the key shortcomings in the field of nanotechnology risk assessment is the lack of techniques capable of source tracing of nanoparticles (NPs). Silica is the most-produced engineered nanomaterial and also widely present in the natural environment in diverse forms. Here we show that inherent isotopic fingerprints offer a feasible approach to distinguish the sources of silica nanoparticles (SiO2 NPs). We find that engineered SiO2 NPs have distinct Si–O two-dimensional (2D) isotopic fingerprints from naturally occurring SiO2 NPs, due probably to the Si and O isotope fractionation and use of isotopically different materials during the manufacturing process of engineered SiO2 NPs. A machine learning model is developed to classify the engineered and natural SiO2 NPs with a discrimination accuracy of 93.3%. Furthermore, the Si–O isotopic fingerprints are even able to partly identify the synthetic methods and manufacturers of engineered SiO2 NPs.Determining the source of nanoparticles is critical for nanotechnology risk assessment. Here, the authors develop an approach that, by taking into account the isotopic signatures of both Si and O, may be able to distinguish between natural and engineered SiO2 nanoparticles, and even those synthesized by different manufacturers.

[1]  G. Jiang,et al.  Isotope Tracers To Study the Environmental Fate and Bioaccumulation of Metal-Containing Engineered Nanoparticles: Techniques and Applications. , 2017, Chemical reviews.

[2]  Shemesh,et al.  A 3000-year climatic record from biogenic silica oxygen isotopes in an equatorial high-altitude lake , 1998, Science.

[3]  T. Hofmann,et al.  Single-particle multi-element fingerprinting (spMEF) using inductively-coupled plasma time-of-flight mass spectrometry (ICP-TOFMS) to identify engineered nanoparticles against the elevated natural background in soils , 2017 .

[4]  M. Rehkämper,et al.  Evaluation of stable isotope tracing for ZnO nanomaterials--new constraints from high precision isotope analyses and modeling. , 2012, Environmental science & technology.

[5]  R. B. Georg,et al.  High temperature silicon isotope geochemistry , 2014 .

[6]  M. Brzezinski,et al.  Silicon-isotope composition of diatoms as an indicator of past oceanic change , 1998, Nature.

[7]  G. Jiang,et al.  Recent advances in the analysis of non-traditional stable isotopes by multi-collector inductively coupled plasma mass spectrometry , 2017 .

[8]  R. Scholz,et al.  Modeled environmental concentrations of engineered nanomaterials (TiO(2), ZnO, Ag, CNT, Fullerenes) for different regions. , 2009, Environmental science & technology.

[9]  D. Mann,et al.  Magnetite pollution nanoparticles in the human brain , 2016, Proceedings of the National Academy of Sciences.

[10]  G. Lowry,et al.  Towards a definition of inorganic nanoparticles from an environmental, health and safety perspective. , 2009, Nature nanotechnology.

[11]  R. Clayton,et al.  Quartz oxygen isotopic stability in relation to isolation from sediments and diversity of source , 1975 .

[12]  C. Lévi-Strauss,et al.  Experimental investigation , 2013 .

[13]  Absar Ahmad,et al.  Fungus-mediated biotransformation of amorphous silica in rice husk to nanocrystalline silica. , 2006, Journal of the American Chemical Society.

[14]  Marcin Banach,et al.  Silver nanoparticles – a material of the future…? , 2016 .

[15]  M. Baskaran,et al.  Handbook of Environmental Isotope Geochemistry: Vol I , 2012 .

[16]  J. H. Reynolds,et al.  Natural variations in the isotopic constitution of silicon , 1953 .

[17]  R. Clayton,et al.  The use of bromine pentafluoride in the extraction of oxygen from oxides and silicates for isotopic analysis , 1963 .

[18]  M. Brzezinski,et al.  Biological fractionation of silicon isotopes in Southern Ocean surface waters , 2004 .

[19]  B. Nowack,et al.  Exposure modeling of engineered nanoparticles in the environment. , 2008, Environmental science & technology.

[20]  G. Jiang,et al.  Natural Silicon Isotopic Signatures Reveal the Sources of Airborne Fine Particulate Matter. , 2018, Environmental science & technology.

[21]  L. Labeyrie,et al.  Temperature dependence of the oxygen isotopic fractionation between diatom silica and water , 1987 .

[22]  Pedro J J Alvarez,et al.  Comparative eco-toxicity of nanoscale TiO2, SiO2, and ZnO water suspensions. , 2006, Water research.

[23]  M. Rehkämper,et al.  High precision 142Ce/140Ce stable isotope measurements of purified materials with a focus on CeO2 nanoparticles , 2016 .

[24]  N. Ediz,et al.  Improvement in filtration characteristics of diatomite by calcination , 2010 .

[25]  R. B. Georg,et al.  New sample preparation techniques for the determination of Si isotopic compositions using MC-ICPMS , 2006 .

[26]  J. Meunier,et al.  Another continental pool in the terrestrial silicon cycle , 2005, Nature.

[27]  R. Clayton,et al.  Oxygen isotope exchange between quartz and water , 1972 .

[28]  R. Siegwolf,et al.  Using Stable Isotopes as Indicators, Tracers, and Recorders of Ecological Change: Some Context and Background , 2007 .

[29]  B. Dupré,et al.  Global silicate weathering and CO2 consumption rates deduced from the chemistry of large rivers , 1999 .

[30]  Mark T. Swihart,et al.  Vapor-phase synthesis of nanoparticles , 2003 .

[31]  H. Zou,et al.  Polymer/silica nanocomposites: preparation, characterization, properties, and applications. , 2008, Chemical reviews.

[32]  L. Labeyrie.  New approach to surface seawater palaeotemperatures using 18O/16O ratios in silica of diatom frustules , 1974, Nature.

[33]  Arturo A. Keller,et al.  Predicted Releases of Engineered Nanomaterials: From Global to Regional to Local , 2014 .

[34]  C. Douthitt.  The geochemistry of the stable isotopes of silicon , 1982 .

[35]  R. Clayton,et al.  Oxygen isotopic fractionation in the system quartz-albite-anorthite-water , 1979 .

[36]  A. Höweling,et al.  Tracing the oxygen isotope composition of the upper Earth's atmosphere using cosmic spherules , 2017, Nature Communications.

[37]  R. Telford,et al.  A 14,000-Year Oxygen Isotope Record from Diatom Silica in Two Alpine Lakes on Mt. Kenya , 2001, Science.

[38]  A. Yassin,et al.  Occupational Exposure to Crystalline Silica Dust in the United States, 1988–2003 , 2004, Environmental health perspectives.

[39]  F. Hu,et al.  A biogenic-silica δ18O record of climatic change during the last glacial–interglacial transition in southwestern Alaska , 2003, Quaternary Research.

[40]  S. Musić,et al.  Precipitation of amorphous SiO2 particles and their properties , 2011 .

[41]  G. Jiang,et al.  Stable silver isotope fractionation in the natural transformation process of silver nanoparticles. , 2016, Nature nanotechnology.

[42]  Brian Gulson,et al.  Stable Isotopic Tracing—A Way Forward for Nanotechnology , 2006, Environmental health perspectives.

[43]  Ismail Ab Rahman,et al.  Synthesis of silica nanoparticles by sol-gel: size-dependent properties, surface modification, and applications in silica-polymer nanocomposites — a review , 2012 .

[44]  Reinout Heijungs,et al.  Setting the stage for debating the roles of risk assessment and life-cycle assessment of engineered nanomaterials. , 2017, Nature nanotechnology.

[45]  P. Westerhoff,et al.  Methods for the Detection and Characterization of Silica Colloids by Microsecond spICP-MS. , 2016, Analytical chemistry.

[46]  Shan Gao,et al.  Direct determination of Si isotope ratios in natural waters and commercial Si standards by ion exclusion chromatography multicollector inductively coupled plasma mass spectrometry. , 2014, Analytical Chemistry.

[47]  Yasuo Yoshioka,et al.  Silica and titanium dioxide nanoparticles cause pregnancy complications in mice. , 2011, Nature nanotechnology.

[48]  Gaël Varoquaux,et al.  Scikit-learn: Machine Learning in Python , 2011, J. Mach. Learn. Res..

[49]  Mario Marchese,et al.  Techniques and applications , 2003 .

[50]  Tao Li,et al.  Using discriminant analysis for multi-class classification: an experimental investigation , 2006, Knowledge and Information Systems.

[51]  Frank von der Kammer,et al.  Where is the nano? Analytical approaches for the detection and quantification of TiO2 engineered nanoparticles in surface waters , 2018 .

[52]  J. Wiederhold.  Metal stable isotope signatures as tracers in environmental geochemistry. , 2015, Environmental science & technology.

[53]  F. Poitrasson,et al.  Precise Determination of Silicon Isotopes in Silicate Rock Reference Materials by MC‐ICP‐MS , 2011 .