Aptazyme Driven Dual-FRET Nanoplatform for Simultaneous Detection of Chlorpyrifos and Lead Ions

Abstract

The co-occurrence of pesticides and heavy metal ions in water resources poses significant health risks, necessitating the development of advanced detection methods capable of simultaneously monitoring of these contaminants. Sometimes, traditional biosensors for multiple target detection may face challenges in detecting chemically distinct analytes due to their signal interference and interdependent detection mechanism. To overcome these challenges, a simple dual target optical biosensor was fabricated for sensitive and efficient measure of chlorpyrifos and lead ions (Pb2+) by utilizing Förster resonance energy transfer (FRET) baseddual recognition enzyme beacon (DRAB) nano-machine. In our design, the self blocked DRAB contains a 6-Carboxy-X-Rhodamine(ROX)-labled chlorpyrifos aptamer at one terminal with its florescence quenched by BHQ-2 strategically positioned at the central region of DRAB, where aptamer terminates. Simultaneously, the Pb2+ dependent substrate strand labeled with FAM is quenched by BHQ-1, which is located at terminal region of DRAB complementary to substrate strand. This assay facilitates in simultaneous and independent detection of chlorpyrifos and Pb2+. Upon the addition of chlorpyrifos, the hairpin-locked aptamer undergoes conformational opening, activating the system and restoring florescene at the ROX emission peak (520). Similarly, the introduction of Pb2+ ions triggers the cleavage of substrate strand, leading to florescence activation at FAM emission peak (620nm). This dual target sensing mechanism ensure highly specificity and sensitivity with LOD for chlorpyrifos is 2.9 nM and LOD for Pb2+ is 0.2 nM. The biosensor enables the generation of independents florescence signal for each analyte,ensuring precise detection of chlorpyrifos and Pb2+ in complex matrices.