The air pollution caused by particulate matters (PMs) poses a severe threat to the human health. In particular, the fine particles with diameter smaller than 2.5 μm (PM 2.5 ) can be carriers of various bacteria and viruses, accelerating spread of epidemic. In this work, we synthesized two robust and flexible conjugated microporous polymer (CMP) aerogels for PMs removal, via one-step coupling polymerization of arylethynylenes and aryl halides with different molecular configuration. The resulting CMP aerogels comprise of hollow nanotubes with 3D porous network and high surface areas up to 660 m 2 /g. The efficiency of CMP aerogels for PM 2.5 and PM 10 was 99.5 ± 0.3 % and 99.8 ± 0.1 % with a long-term durability. In combination with their physicochemical stability and inherent surface hydrophobicity, a high efficiency for PM 2.5 filtration more than 99.6 ± 0.1 % also can be obtained at a high humidity at room temperature both for the two CMP aerogels. In addition, benefiting from the rich alkynyl groups in skeletons, post-modification of the resulting CMP aerogels with thiol-yne chemistry followed by silver ion uptake gives rise to antibacterial materials with outstanding activity for gram-positive strains far superior to other porous organic polymer materials. This work provides a new avenue to fabricate bifunctional CMPs derived porous aerogels for air filtration with high performance and antibacterial activity, and is expected to expand the application of CMPs in environmental purification.
Due to the typical volatility of gaseous pollutant methyl mercaptan (CH 3 SH), the development of a facile, reliable, and accurate onsite environmental surveillance of highly toxic CH 3 SH faces many challenges, but it is critical to environmental atmosphere assessment and safeguarding public health. Here, we prepared a novel bimetallic carbon dots (Fe&Cu@CDs) nanozyme with high peroxidase-mimicking activity to design a portable hydrogel kit for onsite visual H 2 O 2 -self-supplying enzymatic cascade catalytic colorimetric and photothermal signal synergistic amplification dual-modal monitoring of CH 3 SH in atmospheric environment. Assisted by alcohol oxidase (AOX), CH 3 SH could be specifically converted into H 2 O 2 for oxidizing chromogenic substrate 3,3′,5,5′-tetramethylbenzidine (TMB) catalyzed by Fe&Cu@CDs to produce dark blue ox-TMB with absorption at 652 nm and photothermal characters. Consequently, a CH 3 SH concentration-dependent change both in naked-eye color and photothermal effect-triggered temperature were observed. By hybridizing AOX-assisted Fe&Cu@CDs + TMB with agarose, a H 2 O 2 -self-supplying colorimetric and photothermal signal synergistic amplification sensory hydrogel kit integrated with Color Picker APP-installed smartphone and 660 nm laser-equipped handheld thermal imager for CH 3 SH was proposed with acceptable results in atmospheric environment around wastepile ( e.g. , solid waste and food waste piles), which exhibited great potentials to further develop commercial onsite monitoring platforms in warning-early abnormal atmospheric CH 3 SH for safeguarding environmental health.
O -Succinyl- L -homoserine mercaptotransferase (MetZ) is a key enzyme for the synthesis of L -methionine. However, the limited tolerance to high concentrations of substrate methyl mercaptan sodium restricts its industrial applications, while the “trade-off” between activity and stability has always been a challenge for protein engineering. To address this problem, a strategy of dynamic network rigidification-local flexibility regulation was applied in this study to engineer the enzyme from Chromobacterium violaceum ( Cv MetZ). Through consensus sequence analysis and structure-guided design, the hotspot amino acid residues were anchored for mutagenesis. The best mutant T59I/T119Y/A241T was obtained with synergistic enhancement of activity and stability. The half-life ( t 1/2 ) of whole cells harboring the mutant was increased from 3.3 and 1.3 h to 20.6 and 7.2 h, in the presence of 5% and 10% methyl mercaptan sodium, respectively. The engineered enzyme was successfully immobilized with ideal usability, which laid the foundation for efficient and scale-up bioproduction of L -methionine.
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