Dendritic mesoporous silica nanoparticles (DMSNs) are a new class of solid porous materials used for enzyme immobilization support due to their intrinsic characteristics, including their unique open central–radial structures with large pore channels and their excellent biocompatibility. In this review, we review the recent progress in research on enzyme immobilization using DMSNs with different structures, namely, flower-like DMSNs and tree-branch-like DMSNs. Three DMSN synthesis methods are briefly compared, and the distinct characteristics of the two DMSN types and their effects on the catalytic performance of immobilized enzymes are comprehensively discussed. Possible directions for future research on enzyme immobilization using DMSNs are also proposed.

The highly efficient chemoselectivity, stereoselectivity, and regioselectivity render enzyme catalysis an ideal pathway for the synthesis of various chemicals in broad applications. While the cofactor of an enzyme is necessary but expensive, the conversed state of the cofactor is not beneficial for the positive direction of the reaction. Cofactor regeneration using electrochemical methods has the advantages of simple operation, low cost, easy process monitoring, and easy product separation, and the electrical energy is green and sustainable. Therefore, bioelectrocatalysis has great potential in synthesis by combining electrochemical cofactor regeneration with enzymatic catalysis. In this review, we detail the mechanism of cofactor regeneration and categorize the common electron mediators and enzymes used in cofactor regeneration. The reaction type and the recent progress are summarized in electrochemically coupled enzymatic catalysis. The main challenges of such electroenzymatic catalysis are pointed out and future developments in this field are foreseen.

The hollow spherical covalent organic frameworks (COFs) have a wide application prospect thanks to their special structures. However, the controllable synthesis of uniform and stable hollow COFs is still a challenge. We herein propose a self-templated method for the preparation of hollow COFs through the Ostwald ripening mechanism under ambient conditions, which avoids most disadvantages of the commonly used hard-templating and soft-templating methods. A detailed time-dependent study reveals that the COFs are transformed from initial spheres to hollow spheres because of the inside-out Ostwald ripening process. The obtained hollow spherical COFs have high crystallinity, specific surface area (2,036 m²·g⁻¹), stability, and single-batch yield. Thanks to unique hollow structure, clear through holes, and hydrophobic pore environment of the hollow spherical COFs, the obtained immobilized lipase (BCL@H-COF-OMe) exhibits higher thermostability, polar organic solvent tolerance, and reusability. The BCL@H-COF-OMe also shows higher catalytic performance than the lipase immobilized on non-hollow COF and free lipase in the kinetic resolution of secondary alcohols. This study provides a simple approach for the preparation of hollow spherical COFs, and will promote the valuable research of COFs in the field of biocatalysis.

A novel integrated nanobiocatalyst system based on an enzyme@silica nanoflower@metal-organic framework (enzyme@SNF@ZIF-8) structure with improved stability is fabricated for the first time. The versatility of this system is validated using penicillin G acylase (PGA) and catalase (CAT) as model enzymes. The microporous ZIF-8 layer can be controlled by varying the number of ZIF-8 coating cycles, which produces PGA@SNF@ZIF-8 nanobiocatalysts with different ZIF-8 layer thicknesses. After the second ZIF-8 coating cycle, a PGA@SNF@ZIF-8(2) structure with a homogeneous and well-intergrown ZIF-8 layer is formed, which possesses excellent mechanical and chemical stability. Moreover, PGA@SNF@ZIF-8(2) shows improved thermal/storage stability and reusability compared with free PGA and PGA immobilized on silica nanoflowers (PGA@SNF). The obtained CAT-based nanobiocatalysts (CAT@SNF@ZIF-8(2)) also show excellent catalytic performance.