Encapsulating nitroreductase into metal-organic framework: Boosting industrial performance for the reduction of nitro-aromatics

Abstract Traditional chemical methods for nitro reduction are typically conducted under harsh conditions and are readily explosive, such as hydrogen pressurization and zinc powder reduction. Nitroreductase (NTR) as a biocatalyst may represent a promising strategy to solve this synthetic challenging. Unfortunately, due to the availability of this enzyme, the lack of long-term stability as well as challenging recovery process, very limited work was reported about its applicability for the reduction of nitro groups. Here, based on the highly efficient expression of NTR in our lab, we firstly reported the encapsulation of NTR into ZIF-8 to form NTR@ZIF-8. The resulting framework composite demonstrated an excellent protective capability of enzyme against harsh environment and could also simplify the complex downstream separation and recovery operations. Moreover, after five successive cycles of reuse to reduce 4-NP, the residual NTR@ZIF-8 still reserved a certain activity, which can significantly reduce the processing cost and might be applicable in the industries in the future.