In Situ Encapsulation of Organophosphorus Hydrolase into a Reduction-Catalytic Cu-MOF for Chemoenzymatic Cascade Conversion of Methyl Parathion to 4-Aminophenol

The highly toxic organophosphate pesticide methyl parathion (MP) is widely used in agriculture and thus poses significant risks to the environment. Organophosphorus hydrolase (OPH) can effectively catalyze the hydrolysis of MP, but generate a toxic product of 4-nitrophenol (4-NP), so the following reduction of 4-NP to 4-aminophenol (4-AP) with low toxicity but high economic value has been designed for sustainable development. Therefore, the cascade conversion of highly hazardous MP to economically valuable 4-AP is an attractive strategy for both environmental remediation and industrial applications. In this study, we synthesized a reduction-catalytic cupric metal-organic framework (CuBDC) in solvent-free aqueous phase and under mild conditions and in situ encapsulated OPH within CuBDC via a cation polyelectrolyte poly(allylamine hydrochloride) (PAH)-assisted biomineralization, creating a chemoenzymatic cascade catalyst (OPH-PAH@CuBDC) for MP conversion to 4-NP. The optimized OPH-PAH@CuBDC exhibited 154% hydrolysis activity of free OPH, 130% reduction activities of pure CuBDC, and an average cascade conversion rate of 6.2 μmol·min^-1·g_catalyst^-1, affording a complete conversion of 50 μM MP to 4-AP in only 6 min at low reductant concentration (20 mM NaBH₄), due to the Cu²⁺-activation effect on the encapsulated OPH and the PAH-induced exposure of more reduction-catalytic sites, respectively. Furthermore, OPH-PAH@CuBDC retained 95% activity in 10 day storage and about 50% activity in 10 recycles. The results proved that OPH-PAH@CuBDC is a promising chemoenzymatic catalyst with great potential in practical applications for MP detoxification and resourcilization.