Phosphorescence aptasensing system for sulfadimethoxine with petal-like MoS2 nanosheets for signal amplification

The fast and accurate detection of residual veterinary antibiotics in food has great significance for the ecological balance and human health. This study presents a room temperature phosphorescence aptasensing system for sulfadimethoxine (SDM) detection with sulfadimethoxine-aptamer (SDM-APT) modified manganese doped ZnS quantum dots (Mn-ZnS QDs) as the signaling and recognition unit. The signal amplification was achieved by petal-like molybdenum disulfide nano sheets (MoS2 NS). As the selective adsorption of single-stranded DNA (ssDNA) on MoS2 NS, SDM-APT-Mn-ZnS QDs are assembled on the surface of MoS2 NS, and lead to the efficient phosphorescence quenching of Mn-ZnS QDs. Once SDM is brought in the sensing system, the specific interaction between SDM-APT and SDM will switch the conformation of SDM-APT from random coil to hairpin structure, resulting in the exfoliation of SDM-APT-Mn-ZnS QDs from MoS2 NS, along with the phosphorescence recovery. This SDM detection system has a linear range from 2.0 ng/mL to 400 ng/mL with LOD as 0.91 ng/mL (S/N = 3) at the optimal experimental condition. The feasibility, specificity and recovery have been verified from the detection of real samples, interfering experiments and standard recovery experiments. The SDM detection system may also be applied to other residual veterinary drugs with different aptamers.