Mycotoxins are secondary metabolites produced by different species of fungi that colonize several kinds of food and contaminate them with toxins either in the field or after harvest and have a huge economic impact around the world. Due to the variety of structures of these small toxic chemical products (MW around 700), it is impossible to use one standard technique for analysis and/or detection. Practical requirements for high-sensitivity analysis and the need for a specialized laboratory setting creates challenges for routine analysis.<br/><br/>Aptamer-based biosensing technology combined with gold nanoparticle optical transducers provide simple, rapid, and reliable detection methods that can be easily integrated with portable and accessible optical equipment. Among them, label-free surface-enhanced Raman scattering (SERS) is an attractive alternative. By taking advantage of the surface-enhanced effects of gold nanostructures, the Raman signals of aptamers adsorbed on the surface can be enhanced by several orders of magnitude and used in the selective determination of mycotoxins such as ochratoxin A (OTA) and aflatoxin B1 (AFB1) without requiring the presence of a Raman dye.<br/><br/>Label-free SERS sensors for mycotoxin detection have barely been reported. The studies available still need to overcome accessibility issues, as they rely on expensive equipment, benchtop spectrometers, and a clean room facility to prepare the substrates. Herein, we introduced a liquid-phase gold nanoaptasensors system based on gold nanotriangles for label-free determination of OTA and AFB1 by SERS in a simple and accessible manner. Batch-to-batch reproducibility was confirmed by testing the performance of seven independently prepared sensors. Multivariate analysis methods were used to process the Raman spectra and to selectively discriminate mycotoxin content down to the ppb level. Finally, the solvent effect was evaluated to corroborate their influences in the sensitivity and reproducibility of the assay when dealing with real samples.

Accessible mycotoxin identification by label-free SERS nanoaptasensors in solution

2019 Spring National Meeting

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