Metal Halide Perovskite Nanocrystals-Intermediated Hydrogel for Boosting the Biosensing Performance

Metal-halide perovskites have become attractive nanomaterials for advanced biosensors, yet the structural design remains challenging due to the trade-off between environmental stability and sensing sensitivity. Herein, a trinity strategy is proposed to address this issue by integrating Mn (II) substitution with CsPb₂Cl₅ inert shell and NH₂-PEG-COOH coating for designing Mn²⁺-doped CsPbCl₃/CsPb₂Cl₅ core/shell hetero perovskite nanocrystals (PMCP PNCs). The trinity strategy isolates the emissive Mn²⁺-doped CsPbCl₃ core from water and the Mn²⁺ d-d transition generates photoluminescence with a long lifetime, endowing the NH₂-PEG-COOH capped Mn²⁺-doped CsPbCl₃/CsPb₂Cl₅ PNCs with robust water stability and oxygen-sensitive property. Given the structural integration, photoluminescent hydrogel biosensors are designed by embedding the PMCP PNCs into the hydrogel system to deliver on-site pesticide information on food products. Impressively, benefiting from the dual enzyme triggered-responsive property of PMCP PNCs, the hydrogel biosensor is endowed with ultra-high sensitivity toward chlorpyrifos pesticide at the nanogram per milliliter level. Such a robust PMCP PNCs-based hydrogel sensor can provide accurate pesticide information while guiding the construction of photoluminescent biosensors for upcoming on-site applications.