A novel strategy for enhancing the stability of aptamer conformations in heavy metal ion detection.

Detection methods based on aptamer probes have great potential and progress in the field of rapid detection of heavy metal ions. However, the unstable conformation of aptamers often results in poor sensitivity due to the dissociation of aptamer-target complex in real environments. In this study, we developed a locking aptamer probe and combined it with AgInZnS quantum dots for the first time to detect cadmium ions. When cadmium ions are combined with the probe, the cadmium ions are fixed in the core-locking position, forming a stable cavity structure. The limit of detection (LOD) was achieved at a concentration of 6.9 nmol L−1, with a broad detection range from 10 nmol L−1 to 1000 μmol L−1, and good recovery rates (92.93%–102.8 %) were achieved in aquatic product testing. The locking aptamer probe with stable conformation effectively enhances the stability of the aptamer-target complex and remains good stability in four buffer environments as well as a 600 mmol L−1 salt solution; it also exhibits good stability at pH 6.5–7.5 and temperatures ranging from 25 °C to 35 °C. Overall, our study presented a general, simple, and cost-effective strategy for stabilizing aptamer conformations, and used for highly sensitive detection of cadmium ions. A lock-type aptasensor detection of cadmium to enhances the stability of the aptamer-target complex and remains good stability in four buffer environments. [Display omitted] • Truncated and optimized to obtain a locking aptamer probe with good affinity and spatial constraint ability. • For the first time, a detection probe for the specific recognition of cadmium ions was developed and designes. • The lock-type aptasensor has outstanding specificity and the sensitivity for detecting cadmium ions can reach the nmol/L level. • The lock-type aptasensor greatly improves the stability of aptamers in different buffer environments and high-salt environments. [ABSTRACT FROM AUTHOR]