Single-atom catalysts (SACs) are prone to agglomeration or migration during catalytic processes, making the development of highly dispersible SACs greatly essential for the performance of photocatalytic CO2 reduction. Herein, cobalt-containing keto-enamine covalent organic frameworks (COFs) (Co/TpPa-1) are successfully in situ synthesized by utilizing the interlayer nitrogen atom coordinated with metallic cobalt, which is used to effectively prevent the agglomeration of monometallic atoms to ensure the homogeneous dispersion of SACs in the resulting metalized COFs. In the photocatalytic CO2 reduction, the Co/TpPa-1 composite exhibits significantly enhanced performance compared to the TpPa-1 COFs. The CO yield of 0.05 mM Co/TpPa-1 composite is approximately 414.5 μmol g–1 h–1, representing a two-order-of-magnitude improvement over the TpPa-1 COF catalyst (approximately 4.15 μmol g–1 h–1). Moreover, the 0.05 mM Co/TpPa-1 composite shows 99.45% selectivity for CO and good stability, maintaining a over 97% CO2 reduction rate after four cycles. The reason lies in the fact that the interaction between monatomic Co and TpPa-1 COFs enhances visible light absorption and extends the lifetime of the photogenerated carriers by promoting electron transfer through the loaded monatomic Co. This work provides a new idea for the catalyst synthesis with high performance and high selectivity.
Rheumatoid arthritis (RA) is a chronic immune disease characterized by the infiltration of immune cells and the proliferation of fibroblast-like synoviocytes (FLS) at the joint site, leading to inflammation and joint destruction. However, the available treatment options targeting both inflammatory and proliferative FLS are limited. Herein, this work presents three covalent organic frameworks (COFs) photothermal composite systems modified with multi-armed polyethylene glycols (PEG) for the treatment of RA. These systems exhibit a dual response under low pH and high reactive oxygen species (ROS) conditions at the site of inflammation, with a specific focus on delivering the protein drug ribonuclease A (RNase A). Notably, molecular docking studies reveal the interaction between RNase A and NF-κB p65 protein, and Western blotting confirm its inhibitory effect on NF-κB activity. In vitro and in vivo experiments verify the significant reduction in joint swelling and deformities in adjuvant-induced arthritis (AIA) rats after treatment with RNase A delivered by multi-armed PEG-modified COF ligands, restoring joint morphology to normal. These findings underscore the promising therapeutic potential of COFs for the treatment of RA, highlighting their unique capabilities in addressing both inflammatory and proliferative aspects of the disease and expanding the scope of biomedical applications for COFs.
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