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

Abstract 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.