2D covalent organic frameworks (2D COFs) have been recognized as a novel class of photoactive materials owing to their extended π‐electron conjugation and high chemical stabilities. Herein, a new covalent organic framework (Tph‐BDP) is facilely synthesized by using a porphyrin derivative and an organic dye BODIPY derivative (5,5‐difluoro‐2,8‐diformyl‐1,3,7,9‐tetramethyl‐10‐phenyl‐5H‐dipyrrolo[1,2‐c:2′,1′‐f][1,3,2]diazabori‐nin‐4‐ium‐5‐uide) as monomers for the first time, and their unique photosensitive properties endow them excellent simulated oxidase activity under 635 nm laser irradiation that can catalyze the oxidation of 3,3′,5,5′‐tetramethylbenzidine (TMB). Further findings demonstrate that the presence of uranium (UO22+) can coordinate with imines of the oxidation products of TMB, thus modulating the charge transfer process of the colored products accompanied with intensive aggregation and remarkable color fading. This research provides a preparation strategy for COFs with excellent photocatalytic properties and nanozyme activity, and broadens the applications of the simple colorimetric methods for sensitive and selective radionuclide detection.

Bacterial infection causes serious threats to human life, especially with the appearance of antibiotic-resistant bacteria. Phototherapeutic approaches have become promising due to their noninvasiveness, few adverse effects, and high efficiency. Herein, a covalent organic framework (TAPP-BDP) with a conjugated donor–acceptor (D–A) structure has been constructed for efficient photoinduced bacteriostasis. Under the irradiation with a single near-infrared (NIR) light (λ = 808 nm), TAPP-BDP alone involves triple and synergistic bacterial inhibition based on the integration of photodynamic, photothermal, and peroxidase-like enzymatic activities. The unique D–A structure endows TAPP-BDP with a narrow energy band gap, improving its photodynamic and nanozyme activities to generate reactive oxygen species (ROS) to realize the broad-spectrum bactericidal activity. The extended π-conjugated skeleton of TAPP-BDP results in enhanced absorption in NIR, and the remarkable photothermal activity can increase the temperature up to 65 °C to cause efficient bacterial degeneration. TAPP-BDP shows excellent antibacterial efficiency against both Gram-negative and Gram-positive bacteria. Animal experiments further suggest that TAPP-BDP can effectively heal wounds infected with Staphylococcus aureus in living systems.

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Nanozymes are nanomaterials with enzyme-mimetic activity. It is known that DNA can interact with various nanozymes in different ways, enhancing or inhibiting the activity of nanozymes, which can be used to develop various biosensors. In this work, we synthesized a photosensitive covalent−organic framework (Tph-BT) as a nanozyme, and its oxidase and peroxidase activities could be reversely regulated by surface modification of single-stranded DNA (ssDNA) for the colorimetric detection of UO 2 2+ . Tph-BT exhibits excellent oxidase activity and weak peroxidase activity, and it is surprising to find that the UO 2 2+ -specific DNA aptamer can significantly inhibit the oxidase activity while greatly enhancing the peroxidase activity. The present UO 2 2+ interacts with the DNA aptamer to form secondary structures and detaches from the surface of Tph-BT, thereby restoring the enzymatic activity of Tph-BT. Based on the reversed regulation effects of the DNA aptamer on the two types of enzymatic activities of Tph-BT, a novel "off-on" and "on-off" sensing platform can be constructed for the colorimetric analysis of UO 2 2+ . This research demonstrates that ssDNA can effectively regulate the different types of enzymatic activities of single COFs and achieve the sensitive and selective colorimetric analysis of radionuclides by the naked eye.