Label free detection of auramine O by G-quadruplex-based fluorescent turn-on strategy

Auramine o (AO) is a synthetic dye used in paper and textile industries. Although it has been an unauthorized food additive in many countries due to its toxic and carcinogenic possibility, its illegal uses have been detected in certain food products such as pasta, semolina and spices and also in pharmaceuticals. The presence of AO in food products should be monitored, therefore, to minimize the negative health effects on consumers. In this study, a simple, highly sensitive and selective label free detection method was investigated for AO by G-quadruplex-based fluorescent turn-on strategy. The optimum fluorescent detection assay was achieved with a specific G-quadruplex DNA sequence, c-myc, at 400 nM in TrisHCl buffer at pH 7.4. The linearity of fluorescence intensity depending on AO concentration ranged from 0 to 0.07 mM and LOD and LOQ were 3 nM and 10 nM, respectively. The G-quadruplex-based detection assay was highly specific for AO as compared to other two synthetic food colorings and successfully applied to determine AO in pasta, bulgur and curry powder with recoveries in the range from 70.33% to 106.49%. This G-quadruplex-based label free detection assay has a significant potential to be used in the detection of AO in food products.(c) 2021 Elsevier B.V. All rights reserved.

Automated summary

Auramine o (AO) is a synthetic dye used in paper and textile industries. Although it has been banned as a food additive in many countries, it is still illegally used in certain food products and pharmaceuticals. Monitoring the presence of AO in food products is important to minimize health risks. This study developed a simple, sensitive, and selective label-free detection method based on G-quadruplex for AO. The method showed high specificity for AO and was successfully applied to detect AO in pasta, bulgur, and curry powder.