Macrophage-Inspired marine antifouling coating with dynamic surfaces based on regulation of dynamic covalent bonds.

Macrophages can kill bacteria and viruses by releasing free radicals, which provides a possible approach to construct antifouling coatings with dynamic surfaces that release free radicals if the breaking of dynamic covalent bonds is precisely regulated. Herein, inspired by the defensive behavior of macrophages of releasing free radicals to kill bacteria and viruses, a marine antifouling coating composed of polyurethane incorporating dimethylglyoxime (PUx-DMG) is prepared by precise regulation of dynamic oxime-urethane covalent bonds. The obtained alkyl radical (R·) derived from the cleavage of the oxime-urethane bonds manages to effectively suppress the attachment of marine biofouling. Moreover, the intrinsic dynamic surface makes it difficult for biofouling to adhere and ultimately achieves sustainable antifouling property. Notably, the PU50-DMG coating not only presents efficient antibacterial and antialgae properties, but also prevents macroorganisms from settling in the sea for up to 4 months. This provides a pioneer broad-spectrum strategy to explore the marine antifouling coatings.

Hierarchical Nanoheterostructure of HFIP-Grafted α-Fe2O3@Multiwall Carbon Nanotubes as High-Performance Chemiresistive Sensors for Nerve Agents.

New and efficient sensors of nerve agents are urgently demanded to prevent them from causing mass casualties in war or terrorist attacks. So, in this work, a novel hierarchical nanoheterostructure was synthesized via the direct growth of α-Fe2O3 nanorods onto multiwall carbon nanotube (MWCNT) backbones. Then, the composites were functionalized with hexafluoroisopropanol (HFIP) and successfully applied to detect dimethyl methylphosphonate (DMMP)-sarin simulant gas. The observations show that the HFIP-α-Fe2O3@MWCNT hybrids exhibit outstanding DMMP-sensing performance, including low operating temperature (220 °C), high response (6.0 to 0.1 ppm DMMP), short response/recovery time (8.7 s/11.9 s), as well as low detection limit (63.92 ppb). The analysis of the sensing mechanism demonstrates that the perfect sensing performance is mainly due to the synergistic effect of the chemical interaction of DMMP with the heterostructure and the physical adsorption of DMMP by hydrogen bonds with HFIP that are grafted on the α-Fe2O3@MWCNTs composite. The huge specific surface area of HFIP-α-Fe2O3@MWCNTs composite is also one of the reasons for this enhanced performance. This work not only offers a promising and effective method for synthesizing sensitive materials for high-performance gas sensors but also provides insight into the sensing mechanism of DMMP.