Photothermal treatment (PTT) involving a combination of therapeutic modalities recently emerged as an efficient alternative for combating biofilm. However, PTT-related local high temperature may destroy the surrounding healthy tissues. Herein, we present an all-in-one phototherapeutic nanoplatform consisting of l-arginine (l-Arg), indocyanine green (ICG), and mesoporous polydopamine (MPDA), namely, AI-MPDA, to eliminate the already-formed biofilm. The fabrication process included surface modification of MPDA with l-Arg and further adsorption of ICG via π–π stacking. Under near-infrared (NIR) exposure, AI-MPDA not only generated heat but also produced reactive oxygen species, causing a cascade catalysis of l-Arg to release nitric oxide (NO). Under NIR irradiation, biofilm elimination was attributed to the NO-enhanced photodynamic therapy and low-temperature PTT (≤45 °C). Notably, the NIR-triggered all-in-one strategy resulted in severe destruction of bacterial membranes. The phototherapeutic AI-MPDA also displayed good cytocompatibility. NIR-irradiated AI-MPDA nanoparticles not only prevented bacterial colonization but also realized a rapid recovery of infected wounds. More importantly, the all-in-one phototherapeutic platform displayed effective biofilm elimination with an efficiency of around 100% in a abscess formation model. Overall, this low-temperature phototherapeutic platform provides a reliable tool for combating already-formed biofilms in clinical applications.

Flexible zinc–air batteries (ZAB) are a promising battery candidate for emerging flexible electronic devices, but the catalysis‐based working principle and unique semi‐opened structure pose a severe challenge to their overall performance at cold temperature. Herein, we report the first flexible rechargeable ZAB with excellent low‐temperature adaptability, based on the innovation of an efficient electrocatalyst to offset the electrochemical performance shrinkage caused by decreased temperature and a highly conductive hydrogel with a polarized terminal group to render the anti‐freezing property. The fabricated ZABs show excellent electrochemical performances that outperform those of many aqueous ZABs at room temperature. They also deliver a high capacity of 691 mAh g−1 and an energy density of 798 Wh kg−1 at −20 °C (92.7 % and 87.2 % retention of the room temperature counterparts, respectively), together with excellent flexibility and reverting capability.

Cu-NP-embedded hydrogel (BACA/Cu NPs/Gel-MA hydrogel) produces ROS for photothermal therapy, killing bacteria, and promoting wound healing.

No abstract

Metal–nitrogen–carbon (M–N–C) single-atom catalysts (SACs) show high catalytic activity for many important chemical reactions. However, an understanding of their intrinsic catalytic activity remains ambiguous because of the lack of well-defined atomic structure control in current M–N–C SACs. Here, we use covalent organic framework SACs with an identical metal coordination environment as model catalysts to elucidate the intrinsic catalytic activity of various metal centers in M–N–C SACs. A pH-universal activity trend is discovered among six 3d transition metals for hydrogen peroxide (H2O2) synthesis, with Co having the highest catalytic activity. Using density functional calculations to access a total of 18 metal species, we demonstrate that the difference in the binding energy of O2* and HOOH* intermediates (E O2* – E HOOH*) on single metal centers is a reliable thermodynamic descriptor to predict the catalytic activity of the metal centers. The predicted high activity of Ir centers from the descriptor is further validated experimentally. This work suggests a class of structurally defined model catalysts and clear mechanistic principles for metal centers of M–N–C SACs in H2O2 synthesis, which may be further extendable to other reactions.