Bionanotechnology

The nanosciences intend to deliver radical new products and processes at nanoscale dimensions by manipulation of surfaces and macromolecular assemblies. In 2005, Bruce et al. [55] reviewed the role of nanotechnology in food analysis but no real-life application of (bio)nanotechnology in chemical food contaminant analysis was presented. Since then the situation is not so much different. However, it should be noted that any SPR biosensor instrument already used in chemical food contaminant analysis is actually an example of bionanotechnology since the biointeraction is measured within a distance of 150 nanometre of the functionalized surface and the flow cells of the microfluidic system are typically in the order of some tens of nanolitres. For example, by applying SPR, Farre et al. [56] showed part-per-trillion sensitivity for the pesticide atrazine in natural water samples and Haasnoot et al. [57] showed the SPR determination of sulfonamide antibiotics in broiler serum and plasma as a prediction tool for residue levels in edible tissues. Another option is the use of localized surface plasmons (LSPs) sustained by functionalized silver or gold nanoparticles: a highly specific, label-less immunosensor has been constructed for the residue analysis of the anabolic steroid stanozolol down to the nanomolar range [58]. The nanoscale format of SPR can also be coupled successfully to nanoLC/TOFMS as demonstrated for the residue analysis of the antibiotic enrofloxacin in chicken muscle [59]. Gold nanoparticles can also be applied to enhance the performance of immunochromatographic strip tests ("dipsticks") as shown by Tanaka et al. [60]. A special application of nanoparticles in the detection of chemical food contaminants will be the use of quantum dots (QDs). QDs are semiconducting crystals of a few nanometres and have unique photophysical properties such as size-tunable luminescence spectra, high quantum yields, broad absorption and narrow emission wavelengths. As a result they will be increasingly used as fluorescent labels in, for example, immunoassays [61], also in chemical food contaminant and residue analysis. Apart from detection, nanomaterials might be used in sample preparation as well. Zhao et al. [62] used carbon nanotubes as a solid-phase extraction adsorbent for the GC/MS/MS analysis of barbiturate drug residues in pork at sub-ppb levels.

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