During the last 20 years, the analytical community has widened the target area for speciation analysis by a new type of species: nanoparticles. Here we give access to techniques and methods used, as well as other useful information about nanoparticles
Background: Chemical species are defined by the International Union of Pure and Applied Chemistry (IUPAC) as “specific form of an element defined as to isotopic composition, electronic or oxidation state, and/or complex or molecular structure”. The speciation of elements is mandatory for understanding their mobility in the environment, their uptake by organisms, their biological activities and toxicity. Nanoparticles (NPs) are discrete solid pieces of material with at least one dimension in the size range of 1 to 100 nm. Inorganic NPs can be considered a distinct chemical species of elements themselves, and their analysis can therefore be discussed as part of speciation analysis.
In this sense the most simple analytical task is the differentiation of the particular species from the dissolved species. However, more specific characterization is needed to understand the bahavior of NPs in different environmental compartments or organisms.
Nanoparticle size: The size of nanoparticles is critically important in various fields and applications due to the profound impact it has on their properties, behaviors, and performance. Here are some key reasons why nanoparticle size is important:
Surface Area-to-Volume Ratio: As nanoparticles get smaller, their surface area relative to their volume increases significantly. This high surface area is advantageous for various applications, including catalysis, sensors, and drug delivery, as it provides more active sites for interactions with other substances.
Optical Properties: Nanoparticle size can strongly influence their optical properties, such as absorption, scattering, and emission of light. This is crucial in fields like nanophotonics, plasmonics, and the development of nanoscale optical materials.
Electromagnetic Properties: In nanoelectronics and nanomaterials, the size of nanoparticles can affect their electrical and magnetic properties, making them suitable for specific electronic or magnetic applications.
Catalysis: Smaller nanoparticles often exhibit higher catalytic activity due to their increased surface area, making them valuable in catalytic reactions.
Drug Delivery: The size of nanoparticles is critical in drug delivery systems, as it affects their ability to cross biological barriers, target specific cells or tissues, and release drugs in a controlled manner.
Toxicity and Biocompatibility: In the field of nanotoxicology and nanomedicine, nanoparticle size can significantly influence their toxicity and biocompatibility. Smaller nanoparticles may have different interactions with biological systems compared to larger ones.
Stability and Aggregation: Nanoparticle size can impact their stability in colloidal solutions. Smaller nanoparticles are often more prone to aggregation due to increased Brownian motion, which can affect their performance and applications.
Drug Solubility and Bioavailability: In pharmaceuticals, the size of nanoparticles can improve the solubility of poorly water-soluble drugs, increasing their bioavailability.
Imaging: Nanoparticle size is crucial in biomedical imaging techniques like magnetic resonance imaging (MRI) and computed tomography (CT) scanning, as it affects the contrast and distribution of imaging agents.
Mechanical Properties: In nanomaterials and nanocomposites, nanoparticle size can influence the mechanical properties of the materials, such as strength, stiffness, and toughness.
Transport and Diffusion: The size of nanoparticles affects their transport and diffusion properties, which is important in applications like filtration, membrane technologies, and drug transport through biological barriers.
Environmental and Ecological Impact: In environmental science, understanding the size distribution of nanoparticles is critical for assessing their transport, behavior, and potential ecological impact in natural systems.
In summary, the size of nanoparticles is a fundamental parameter that influences their performance and behavior in various applications, making it a critical factor to consider when designing, characterizing, and utilizing nanoparticles in science and technology.
Nanoparticles may be consistent of a single constituent, or are formed by two or more components. In case of a single component, speciation analyses may involve determining the chemical state or oxidation state of metal nanoparticles. For example, in the case of metal nanoparticles, speciation analysis may aim to distinguish between metallic, oxide, or other forms of the same metal.
Some nanoparticles are designed with a core-shell structure, where different materials are present in the core and the shell. Speciation analysis can be used to determine the composition, structure, and distribution of materials in such nanoparticles.
Engineered nanomaterials are nowadays widely integrated into consumer and industrial products. Besides cosmetic and cleaning products, food is a major source of exposure of consumers to NPs through ingestion. Also nanomaterials released to the environment can be taken up by organisms and re-enter the food web. Even further, NPs can be formed naturally in the environment or in-vivo by the organisms themselves. In order to characterize and quantify NPs in products and in the environment, several analytical techniques have been developed or adapted.
Among these techniques are single-particle ICP-MS and ICP-MS coupled to separation techniques like field flow fractionation (FFF), capillary electrophoresis (CE), hydrodynamic chromatography (HDC) and reversed phase HPLC. Bio-imaging techniques such as laser ablation ICP-MS, nanoscale secondary ion mass spectrometry (nano-SIMS) and X-ray fluorescence support the qualitative analysis of NPs, whereas electron microscopy is typically considered the gold standard when it comes to determination of particle sizes. Electron microscopy provides additional information on particle shape, crystal structure and if combined with Energy Dispersive X-ray Spectroscopy (EDS), chemical composition can be determined.
Especially challenging is the sample preparation as NPs can agglomerate, aggregate, dissolve or change their crystalline structure or chemical composition. They interact with matrix components and surfaces and might undergo changes.
Apart from size and composition, there are other parameters defining the characteristics of nanoparticles that have to be evaluated by methods beyond speciation analysis, such as nanoparticle coatings, surface functionalization, particle shape or aggregation.
Nanoparticle coating Many nanoparticles have coatings or surface modifications, such as organic ligands, polymers, or surfactants. Nanoparticle analysis may involve characterizing the nature and composition of these coatings, as they can significantly impact the nanoparticles' behavior and interactions.
Nanoparticle Surface Functionalization Understanding the nature of functional groups or chemical modifications on the nanoparticle surface is another aspect of nanoparticle analysis, especially for nanoparticles used in various applications like drug delivery or catalysis. Nanoparticle Aggregates and Clusters Nanoparticle analysis can help identify the specific forms or arrangements of nanoparticles within aggregates or clusters, which can affect their properties and reactivity.
For a complete understanding of the behavior of NPs, often a combination of several analytical techniques is required.
The following listing gives access to the major topics discussed in the framework of NPs analysis.
Regulations and legislation
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Abdul Wahab, Asma Munir, Muhammad Hamzah Saleem, Mukhtar Iderawumi AbdulRaheem, Humera Aziz, Manar Fawzi Bani Mfarrej, Gholamreza Abdi, Interactions of Metal‐Based Engineered Nanoparticles with Plants: An Overview of the State of Current Knowledge, Research Progress, and Prospects, J. Plant Growth Regul., 42 (2023) 5396-5416. DOI: 10.1007/s00344-023-10972-7.
Magdalena Borowska, Krzysztof Jankowski, Basic and advanced spectrometric methods for complete nanoparticles characterization in bio/eco systems: current status and future prospects, Anal. Bioanal. Chem., 415 (2023) 4023-4038. DOI: 10.1007/s00216-023-04641-7
Maha M. El-Kady, Iqbal Ansari, Charu Arora, Nidhi Rai, Sanju Soni, Dakeshwar Kumar Verma, Priyanka Singh, Alaa El Din Mahmoud, Nanomaterials: A comprehensive review of applications, toxicity, impact, and fate to environment, J. Mol. Liq-, 370 (2023) 121046. DOI: 10.1016/j.molliq.2022.121046
Shikha Singh, Sheo Mohan Prasad, Gausiya Bashri, Fate and toxicity of nanoparticles in aquatic systems, Acta Geochim., 42 (2023) 63-76. DOI: 10.1007/s11631-022-00572-9
Andreas Gondikas, Julian Alberto Gallego-Urrea, Karin Mattsson, Nanoparticles in the Marine Environment, in: J. Blasco, A. Tovar-Sánchez(eds.), Marine Analytical Chemistry, Springer, 2022, 323-348. DOI: 10.1007/978-3-031-14486-8_7
Dominique Bazin, Nanomaterials in medicine: a concise review of nanomaterials intended to treat pathology, nanomaterials induced by pathology, and pathology provoked by nanomaterials, C.R. Chimie, 25/S3 (2022) 165-188. DOI: 10.5802/crchim.194
Annika Durve Gupta, Sonali Zankar Patil, Potential Environmental Impacts of Nanoparticles Used in Construction Industry, in: J. A. Malik and S. Marathe (eds.), Ecological and Health Effects of Building Materials, Springer, 2022, 159-183. DOI: 10.1007/978-3-030-76073-1_10
Fabienne Séby,Metal and metal oxide nanoparticles in cosmetics and skin care products, in: R. Milacic, J. Scancar, H. Goenaga Infante, J. Vidmar, Analysis and Characterisation of Metal-Based Nanomaterials, Elsevier, 2021, 381-427. DOI: 10.1016/bs.coac.2021.02.009
Georgios Fytianos, Abbas Rahdar, George Z. Kyzas, Nanomaterials in Cosmetics: Recent Updates, Nanomaterials, 10 (2020) 979. DOI: 10.3390/nano10050979
Abbas Mohajerani, Lucas Burnett, John V. Smith, Halenur Kurmus, John Milas, Arul Arulrajah, Suksun Horpibulsuk, Aeslina Abdul Kadir, Nanoparticles in Construction Materials and Other Applications, and Implications of Nanoparticle Use, Materials, 12 (2019) 3052; DOI: 10.3390/ma12193052
Analytical Techniques for NP Analysis
Qingsheng Bai, Yongguang Yin, Yanwanjing Liu, Haowen Jiang, Mengxin Wu, Weidong Wang, Zhiqiang Tan, Jingfu Liu, Myeong Hee Moon, Baoshan Xing, Flow field-flow fractionation hyphenated with inductively coupled plasma mass spectrometry: a robust technique for characterization of engineered elemental metal nanoparticles in the environment, Appl. Spectros. Rev., 58/2 (2023) 110-131. DOI: 10.1080/05704928.2021.1935272
Ziwei Meng, Lingna Zheng, Hao Fang, Pu Yang, Bing Wang, Liang Li, Meng Wang, Weiyue Feng, Single Particle Inductively Coupled Plasma Time-of-Flight Mass Spectrometry—A Powerful Tool for the Analysis of Nanoparticles in the Environment, Processes, 11/4 (2023) 1237. DOI: 10.3390/pr11041237
Francisco Laborda, Isabel Abad-Alvaro, María S. Jiménez, Eduardo Bolea, Catching particles by atomic spectrometry: Benefits and limitations of single particle - inductively coupled plasma mass spectrometry, Spectrochim. Acta B, 199 (2023) 106570. DOI: 10.1016/j.sab.2022.106570
Jeremie Gouyon, Ariane Boudier, Fatima Barakat, Arnaud Pallotta, Igor Clarot, Taylor dispersion analysis of metallic-based nanoparticles – A short review, Electrophoresis, 43/23-24 (2022) 2377-2391- DOI: 10.1002/elps.202200184
Isabelle A.M. Worms, Vera I. Slaveykova, Asymmetrical Flow Field-Flow Fractionation Coupled to ICP-MS for Characterization of Trace Metal Species in the Environment from Macromolecular to Nano-Assemblage Forms: Current Challenges for Quantification, Chimia 76 (2022) 34–44. DOI: 10.2533/chimia.2022.34
M. Resano, M. Aramendía, E. García-Ruiz, A. Bazo, E. Bolea-Fernandez, F. Vanhaecke, Living in a transient world: ICP-MS reinvented via time-resolved analysis for monitoring single events, Chem. Sci., 13 (2022) 4436. DOI: 10.1039/d1sc05452j
Adam Laycock, Nathaniel J. Clark, Robert Clough, Rachel Smith, Richard D. Handy, Determination of metallic nanoparticles in biological samples by single particle ICP-MS: a systematic review from sample collection to analysis, Environ. Sci.: Nano, 9 (2022) 42. DOI: 10.1039/d1en00680k
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Marco Roman, Hydrodynamic chromatography for the characterization of inorganic nanoparticles, in: R. Milacic, J. Scancar, H. Goenaga Infante, J. Vidmar, Analysis and Characterisation of Metal-Based Nanomaterials, Elsevier, 2021, 121-171. DOI: 10.1016/bs.coac.2021.02.005
Heike Traub, Imaging of metal-based nanoparticles in tissue and cell samples by laser ablation inductively coupled plasma mass spectrometry, in: R. Milacic, J. Scancar, H. Goenaga Infante, J. Vidmar, Analysis and Characterisation of Metal-Based Nanomaterials, Elsevier, 2021, 173-240. DOI: 10.1016/bs.coac.2021.01.006
Maria Montes-Bayón, Jörg Bettmer,The use of high performance liquid chromatography—Inductively coupled plasma-mass spectrometry in the analysis of inorganic nanomaterials, in: R. Milacic, J. Scancar, H. Goenaga Infante, J. Vidmar, Analysis and Characterisation of Metal-Based Nanomaterials, Elsevier, 2021, 285-301. DOI: 10.1016/bs.coac.2021.02.007
Kenneth Flores, Reagan S. Turley, Carolina Valdes, Yuqing Ye, Jesus Cantu, Jose A. Hernandez-Viezcas, Jason G. Parsons & Jorge L. Gardea-Torresdey, Environmental applications and recent innovations in single particle inductively coupled plasma mass spectrometry (SP-ICP-MS), Appl. Spec. Rev., 56/1 (2021) 1-26. DOI: 10.1080/05704928.2019.1694937
Petra Krystek, Ciprian M. Cirtiu, Hedwig Braakhuis, Margriet Park, Wim H. de Jong, Inductively Coupled Plasma-Mass Spectrometry in Biodistribution Studies of (Engineered) Nanoparticles, in: R.A. Meyers (ed.), Encyclopedia Anal. Chem., wiley, 2019, 1-23. DOI: 10.1002/9780470027318.a9337.pub2
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Yu-Feng Li, Jiating Zhao, Yuxi Gao, Bai Li, Chunying Chen, Study on the Toxicology of Nanomaterials by Synchrotron Radiation Techniques, in: Chunhai Fan, Zhentang Zhao, Synchrotron Radiation in Materials Science: Light Sources, Techniques, and Applications, Volume 1, Wiley, 2018, 597-631. DOI: 10.1002/9783527697106.ch15
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Bartlomiej Kowalczyk, István Lagzi, Bartosz A. Grzybowski, Nanoseparations: Strategies for size and/or shape-selective purification of nanoparticles, Curr. Opin. Colloid Interface Sci., 16 (2011) 135-148. DOI: 10.1016/j.cocis.2011.01.004