With the rapid development of modern society, environmental problems, including excessive amounts of CO₂ released in the atmosphere, are becoming more and more serious. It is necessary to develop new materials and technologies to reduce pollution. Among them, metal–organic frameworks (MOFs) have shown potential for application in the area of catalysis due to their ultra-high specific surface area, structural versatility, and designability as well as ease of modification and post-synthesis. Herein, we summarize recent research advances by use of MOFs for boosting CO₂ conversion. Furthermore, challenges and possible research directions related to further exploration are also discussed.

In situ encapsulation of enzymes into hydrogen-bonded organic frameworks (HOFs) offers a promising strategy to enhance enzyme durability and activity recovery in biocatalysis. In this study, we report the immobilization and stabilization of catalase (CAT) and α-amylase (α-Amy) using a novel charge-assisted HOF, TNU-14. This HOF is constructed from tiramidinium and tricarboxylate building blocks under ambient conditions. Benefiting from the electrostatic interactions between the negatively charged enzyme surfaces and the positively charged tiramidinium units, the TNU-14 exoskeleton forms around the enzymes within 15 minutes. As a result, TNU-14 effectively protects the enzymes from degradation while maintaining their activity under harsh chemical and physical conditions, including acidic or alkaline environments, proteolytic enzyme trypsin, chaotropic agent urea, high temperatures, and through at least ten catalysis/filtration cycles. This study represents the first demonstration of a charge-assisted HOF scaffold assembled from trigonal building blocks for enzyme immobilization, paving the way for developing a toolset for enzyme and protein carriers.

Polyetheretherketone (PEEK) is considered to be a potential material for oral implants due to its elastic modulus being similar to that of human cortical bone. However, the poor antibacterial, anti-inflammatory, and osseointegration properties of bioinert PEEK have hindered its clinical application. Therefore, this study designed and constructed a pH-responsive PEEK implant with a bilayer core–shell zeolitic imidazolate framework-8 (ZIF-8) structure loaded on its surface, with an antimicrobial peptide (KR12) encapsulated in the outer shell and an osteogenic peptide (osteogenic growth peptide ) encapsulated in its inner core. In this study, the bilayer core–shell ZIF-8 structure was confirmed to have pH-responsive properties. In vitro studies proved that the implant could promote bone marrow mesenchymal stem cells’ proliferation and differentiation and the M1 phenotype to M2 phenotype conversion of RAW 264.7 and could inhibit bacterial adhesion and proliferation. By constructing rats’ distal femur with/without infection models, it was further demonstrated that the novel implant could effectively inhibit bacterial adhesion and growth, inhibit inflammation, and promote peri-implant osseointegration, which was more substantial when the local area was infected and the pH was lower than that of normal tissue. Collectively, the results suggest that this novel pH-responsive PEEK implant loaded with a bilayer core–shell ZIF-8 structure is a promising peptide delivery implant system, which is well suited for dental applications and offers a potential solution for the prevention of infection during the early phase after implantation.