Signal-off nanozyme-based colorimetric aptasensor for sensitive detection of ampicillin using MnO2 nanoflowers and gold nanoparticles

The combination of nanomaterials possessing distinct characteristics and the precision of aptamers facilitates the creation of biosensors that exhibit exceptional selectivity and sensitivity. In this manuscript, we present a highly sensitive aptasensor that utilizes the distinctive characteristics of MnO2 nanoflowers and gold nanoparticles to selectively detect ampicillin (AMP). In this aptasensor, the mechanism of signal change is attributed to the difference in the oxidase-mimicking activity of MnO2 nanoflowers in the presence of a free sequence. The inclusion of AMP hindered the creation of a double-stranded DNA configuration through its binding to the aptamer, resulting in an observable alteration in absorbance. The relative absorbance varied linearly with the concentration of AMP in the range of 70 pM to 10 nM with a detection limit of 21.7 pM. In general, the colorimetric aptasensor that has been developed exhibits exceptional selectivity and remarkable stability. It also demonstrates favorable performance in human serum, making it a highly reliable diagnostic tool. Additionally, its versatility is noteworthy as it holds great potential for detecting various antibiotics present in complex samples by merely replacing the utilized sequences with new ones.