Employment of mixed aptamers and gold nanobipyramids toward a paper-based aptasensor for simultaneously visual screening and accurate detection of eight sulfonamides

A variety of sulfonamides (SAs) are extensively utilized in animal husbandry and aquaculture, necessitating the development of high-throughput methods for the rapid screening and accurate determination of multiple, ideally all commonly-applied SAs, in animal-derived foodstuffs. We herein developed a paper-based colorimetric aptasensor for the detection of eight different SAs employing a mixture of two broad-specific aptamers as bio-receptor, ascorbic acid (AA)-mediated gold nanobipyramids (AuNBPs) growth for generating color signals, and a paper-based analytical device (PAD) for stabilizing and enhancing color signals. The aptasensor exhibits target SAs concentration-corresponding multiple color changes and has excellent specificity. It can be used to visually screen eight SAs (either individually or collectively) with a visual detection limit (LOD) of 4.0 μM, and quantitatively detect these SAs (either individually or collectively) with a spectrometry LOD of 0.2 μM. Importantly, the signals of the aptasensor can be stably stored for one month for later verification, and the spectrometry LOD is lower than the maximum residue limit (MRL) of total SAs in animal-derived foodstuffs. The aptasensor was successfully applied to detect eight SAs (either individually or collectively) in milk samples with a recovery of 89% - 95% and a relative standard deviation (RSD, n  = 5) < 8%. The results obtained with the aptasensor were consistent with those obtained using commercial ELISA kit. These findings demonstrated that the aptasensor simultaneously meets the requirement of instrument-free screening and quantitative determination of eight SAs in animal-derived foods, making it a promising approach for ensuring the consumption safety of animal-derived foodstuffs.