Interfacial coordination reconstruction of enzyme-MOF driven by [Fe(CN)6]3- for constructing hollow nanoreactors toward ultrasensitive organophosphate pesticides sensing.

Metal-organic frameworks (MOFs) provide an ideal confinement platform for enzyme immobilization. However, their intrinsically narrow microporous diffusion channels create severe mass transport limitations that significantly restrict the catalytic activity of encapsulated enzymes. Here, we report a hierarchical enzyme nanoreactor constructed via an interfacial reconstruction strategy triggered by hexacyanoferrate ([Fe(CN)6]3-) ions, in which Prussian blue analogues (PBAs) are directly generated on a ZIF-67 scaffold preloaded with acetylcholinesterase (AChE). This transformation remodels the originally dense MOF into a hierarchically porous architecture, thereby generating a more favorable microenvironment that improves substrate diffusion and enzyme accessibility, ultimately leading to enhanced catalytic performance. Besides, PtNPs were introduced via in situ reduction to enhance conductivity, accelerate electron transfer, and further improve the sensitivity of the sensor. On this basis, the CS-AChE@ZIF-67@PBA4-Pt/GCE (CS-AZP4-Pt/GCE) biosensor was further constructed for the ultrasensitive determination of organophosphorus pesticides (OPs) and carbamate pesticides (CPs). The sensor exhibits wide linear ranges (3.60 × 10-13-3.60 × 10-6 M for monocrotophos and 1.24 × 10-12-1.24 × 10-6 M for carbaryl), ultralow detection limits (3.62 × 10-14 M and 5.78 × 10-13 M, respectively), along with satisfactory anti-interference capability and operational stability. This study proposes a strategy to overcome diffusion limitations during enzymatic catalysis through interface reconstruction, offering a novel approach to the design of hierarchically structured nanoreactors for high-performance biosensing applications.