Characterisation of nanomaterials in biological samples.

Abstract

The novel properties of nanomaterials and their increasing use have led to enormous research and development activity and significant markets of consumer products containing nano-objects. Many of the nano-objects used in these products have been incorporated intentionally or occur accidentally. Nano-objects are defined as having at least one dimension between 1 nm and 100 nm (ISO/TS 80004-1) and this is the primary criterion that makes them “nano.” Examples of nano-objects are those with metal cores (e.g., metals, metals oxides, quantum dots, alloys, and core–shell materials), and selected carbonaceous nano-objects (e.g., carbon nanotubes). Examples of biological matrices where nanomaterials are used include food, food packaging, cosmetics, pharmaceuticals, nutraceuticals, etc. Although there is concern about the possible toxic effects of nanomaterials because of their unique properties, there is no definitive proof for toxicity. In vitro nanotoxicology studies, in the short term, and the quantification of human exposure, in the long term, will require metrologically validated methods for the detection and characterisation of manufactured nano-objects in complex matrices. Such methods are scarce and, therefore, urgently needed to support upcoming regulation and enable quality control of existing products. Efforts to establish regulations and guidelines related to the use and characterisation of nanomaterials have increased over the last 5 years. The EU Cosmetic Product Regulation (1223/2009) currently defines a cosmetic nanomaterial ingredient as follows: ‘nanomaterial’ means an insoluble or biopersistant and intentionally manufactured material with one or more external dimensions, or an internal structure, on the scale from 1 to 100 nm. Recommendations from the EU Commission published in October 2011 (2011/696/EU) stated that for regulatory purposes, the size distribution of a material should be presented as size distribution based on the number concentration (i.e., the number of objects within a given size range). This recommendation is in contrast to the mass fraction of nanoscale particles in the nanomaterial, as a small mass fraction may contain the largest number of particles. In 2011, FDA released guidelines for industry (2011-D-04890002) with regards to the use of nanoparticles as food additives. The British Standards Institute has recently released guidelines (PAS 139:2012) on the detection and characterisation of manufactured nano-objects in complex matrices. These definitions, recommendations, and guidelines suggest that proper characterisation of nanomaterials in food and consumer products etc. is a demanding task. Analytical techniques that have potential for the characterisation of nanomaterials in biological samples include fractionation techniques such as field flow fractionation, size exclusion chromatography, hydrodynamic chromatography, dialysis, filtration, and ultrafiltration, and detection Published in the topical collection Characterisation of Nanomaterials in Biological Sampleswith guest editors Heidi Goenaga-Infante and Erik H. Larsen.