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2Detection of mycotoxins using SERS-based aptamers
M. Moskovskiy1*, R. Alieva2, S. Kuznetsov1, V. Novikov1, A. Dorokhov1, E. Zavyalova2
1-Federal Scientific Agro-Engineering Center VIM, 1st Institutskiy Proezd 5, 109428 Moscow, Russia 2- Chemistry Department of Lomonosov Moscow State University, Moscow, Russia
Mycotoxins are a group of compounds originating from the metabolism of filamentous fungi that causes many diseases. Fungi infect different plants contaminating food products with mycotoxins. More than 300 mycotoxins were found to induce toxicological effects in mammals. Among others, trichothecene type A (T-2 toxin) is one of the most dangerous mycotoxins because of the systemic toxicity can result from any route of exposure, i.e., dermal, oral, or respiratory [1].
In this work, we applied the surface-enhanced Raman spectroscopy (SERS), which is a highly sensitive and robust technique that provides a fingerprint of the analyte with a typical surface-assessed signal intensity increase by 106 - 108 times [2].
In order to determine the presence of mycotoxins, the new aptamers were developed. They are artificially structured DNA or RNA oligonucleotides that can bind a chemical or biological target with high affinity and specificity. In this work, we estimated their affinity to mycotoxins, thermal stability, and thermal stability of a chosen aptamer in various salts that are significant for SERS intensity.
We obtained SERS spectra of T-2 and DON mycotoxins solutions with different mycotoxin content. Purified toxins (standards for chromatographic determination) were used in this experiment. Figure 1 shows the increase of the peak intensity of the band at about 1587 cm-1 with the content growth from 0 to 4 ^g/mL. For T-2, this dependence is linear throughout this concentration range. In the case of DON, we can see a dramatic nonlinear increase of the band intensity starting with 3.5 (ig/mL. We assume this is due to two sites of DON binding within the aptamer.
Toxin,
Figure 1. The dependence of SERS intensity of the peak at 1587 cm-1 on T-2 and DON concentration.
To sum up, the demonstrated SERS technique with the new developed aptamers can be used to determine the presence and concentration of mycotoxins in solutions. This test system is rapid (<20 min) and cheap consuming the simplest silver nanoparticles and the trace amounts of DNA aptamers.
[1] E. Janik, M. Niemcewicz, M. Podogrocki, et al, T-2 toxin - the most toxic trichothecene mycotoxin: metabolism, toxicity, and decontamination strategies, Molecules, vol. 26, art. № 6868, (2021).
[2] P. A. Mosier-Boss, Review of SERS substrates for chemical sensing, Nanomaterials, vol. 7, art. № 142, (2017).
