Illustrating the Fate of Methyl Radical in Photocatalytic Methane Oxidation over Ag-ZnO by in situ Synchrotron Radiation Photoionization Mass Spectrometry.

Photocatalysis has emerged as an ideal method for the direct activation and conversion of methane under mild conditions. In this reaction, methyl radical (⋅CH3 ) was deemed a key intermediate that affected the yields and selectivity of the products. However, direct observation of ⋅CH3 and other intermediates is still challenging. Here, a rectangular photocatalytic reactor coupled with in situ synchrotron radiation photoionization mass spectrometry (SR-PIMS) was developed to detect reactive intermediates within several hundred microseconds during photocatalytic methane oxidation over Ag-ZnO. Gas phase ⋅CH3 generated by photogenerated holes (O- ) was directly observed, and its formation was demonstrated to be significantly enhanced by coadsorbed oxygen molecules. Methoxy radical (CH3 O⋅) and formaldehyde (HCHO) were confirmed to be key C1 intermediates in photocatalytic methane overoxidation to CO2 . The gas-phase self-coupling reaction of ⋅CH3 contributes to the formation of ethane, which indicates the key role of ⋅CH3 desorption in the highly selective synthesis of ethane. Based on the observed intermediates, the reaction network initiated from ⋅CH3 of photocatalytic methane oxidation could be clearly illustrated, which is helpful for studying the photocatalytic methane conversion processes.

A gentamicin-thioctic acid multifunctional hydrogel for accelerating infected wound healing.

Bacterial infections remain a major concern during wound healing and tissue bonding. The excessive proliferation of bacteria will seriously hinder the repair of the wound and even lead to death. Generally, surgical sutures might cause damage to the surrounding tissues and inevitable infection due to the unfixed shape of the wound. Thus, it is urgent to develop novel antibacterial skin dressing with self-healing and strong adhesion properties. Herein, we prepared an antibacterial and self-healable hydrogel with strong adhesion activity through natural small molecules, including thioctic acid TA and gentamicin (GM). The rapid ring-opening-polymerization of the TA (PTA) forms the backbone of macromolecules, and the functional hydrogel was constructed with the crosslinking of GM, termed as G-PTA, which offers hydrogen bonding interactions between the amino and hydroxyl groups of GM and carboxylic group side chains of poly(TA). The synthesized hydrogel exhibited rapid self-healing ability and strong tissue adhesion due to the internal dynamic disulfide bonds and multiple hydrogen bonds. Importantly, the introduction of GM enabled the G-PTA hydrogel to sustainably release antibiotics and exhibit a durative antibacterial effect with the degradation of PTA, which further shorten the therapeutic time and enhance tissue regeneration in a wound infection model. The in vitro and in vivo experiments demonstrate that the G-PTA hydrogel has potential as a surgical antibacterial biological adhesive, especially for bacterial wound infections.