Latest ArticlesImmobilizing enzyme to nano interfaces has demonstrated to be a favorable strategy for prompting the industrialized application of enzyme. Despite tremendous endeavor has been devoted to using gold nanoparticles (AuNPs) as conjugation matrix due to its fascinating physico-chemical properties, maintaining enzymatic activity while circumventing cumbersome modification remains a formidable challenge. Herein, the freezing-directed conjugation of enzyme/nano interfaces was constructed without extra reagent. As the proof of concept, glucose oxidase (GOx) was chosen as model enzyme. The one-pot conjugation process can be facilely completed at −20 ℃ under aqueous solution. Moreover, with the loading of GOx on AuNP at freezing, the enzyme exhibited superior catalytic activity and stability upon thermal and pH perturbation. The mechanism of boosted activity was then discussed in detail. It was found that higher loading density under freezing condition and more enzyme tending to bind AuNPs via Au-S bond were the main factors for the superior activity. More importantly, this methodology was universal and can also be applied to other enzyme which contains natural cysteine, such as horseradish peroxidase (HRP) and papain. This facile conjugation strategy accompanied by remarkable bioactivity expand the possibilities for enzymatic biosensing, microdevice and even drug delivery.
A general, facile and eco-friendly iron catalysis enables oxidation of unstrained tertiary aromatic alcohols to ketones through C−C bond cleavage even with H2O2 as the oxidant. Notably, this transformation can tolerate oxidation-labile functional groups. The robustness of this method is further demonstrated on the late-stage oxidation of complex bioactive molecules.
Unnatural amino acids (UAAs) have broad applications in pharmaceutical sciences and biological studies. Current synthetic methods for UAAs mainly rely on asymmetric catalysis and often require several steps. There is a lack of direct and simple methods. To address this challenge, we designed the LADA (labeling-activation-desulfurization-addition) strategy: selective labeling and activation of cysteine residues, the photocatalytic desulfurization and the subsequent radical addition to alkenes. Although composed of two steps, it is one-pot synthesis and has advantages such as high functional group tolerance, biocompatible reaction condition, and retained stereochemistry. This highly efficient strategy was successfully applied in the direct synthesis of unnatural amino acids and modifications of peptides with more than 50 examples.
Droplet manipulation on an open surface has great potential in chemical analysis and biomedicine engineering. However, most of the reported platforms designed for the manipulation of water droplets cannot thoroughly solve the problem of droplet evaporation. Herein, we report a shape-reconfigurable micropillar array chip for the manipulation of water droplets, oil droplets and water-in-oil droplets. Water-in-oil droplets provide an enclosed space for water droplets, preventing the evaporation in an open environment. Perfluoropolyether coated on the surface of the chip effectively reduces the droplet movement resistance. The micropillar array chip has light and magnetic dual-response due to the Fe3O4 nanoparticles and the reduced iron powder mixed in the shape-memory polymer. The micropillars irradiated by a near-infrared laser bend under the magnetic force, while the unirradiated micropillars still keep their original shape. In the absence of a magnetic field, when the micropillars in a temporary shape are irradiated by the near-infrared laser to the transition temperature, the micropillars return to their initial shape. In this process, the surface morphology gradient caused by the deformation of the micropillars and the surface tension gradient caused by the temperature change jointly produce the driving force of droplet movement.
Fast Fe(Ⅲ)/Fe(Ⅱ) circulation in heterogeneous peroxymonosulfate (PMS) activation remains as a bottleneck issue that restricts the development of PMS based advanced oxidation processes. Herein, we proposed a facile ammonia reduction strategy and synthesized a novel FeVO3-x catalysts to activate PMS for the degradation of a typical pharmaceutical, carbamazepine (CBZ). Rapid CBZ removal could be achieved within 10 min, which outperforms most of the other iron or vanadium-based catalysts. Electron paramagnetic resonance analysis and chemical probe experiments revealed SO4•−, •OH, O2•− and high valent iron (Fe(Ⅳ)) were all generated in this system, but SO4•− and Fe(Ⅳ) primarily contributed to the degradation of CBZ. Besides, X-ray photoelectron spectroscopy and X-ray adsorption spectroscopy indicated that both the generated low-valent V provides and oxygen vacancy acted as superior electron donors and accelerated internal electron transfer via the unsaturated V−O−Fe bond. Finally, the proposed system also exhibited satisfactory performance in practical applications. This work provides a promising platform in heterogeneous PMS activation.
Artificial photocatalysis offers a promising strategy to sustainably produce hydrogen peroxide (H2O2) that is one of the most valuable multifunctional chemicals. Among various photocatalysts, polymeric carbon nitride (pCN) has drawn continuous attention in non-sacrificial H2O2 production. However, the poor activity of half reactions, i.e., the oxygen reduction reaction (ORR) and water oxidation reaction (WOR), greatly restricts the efficiency of photocatalytic H2O2 production. In this highlight, we discuss the significant advances in molecular engineering of carbon nitrides for H2O2 photosynthesis and the importance of the deep understanding of the photocatalysis process for rational design and reaction pathways of organic conjugated polymers to address the growing H2O2 demand. Furthermore, we summarize the emerging applications of photocatalytic H2O2 productions beyond energy and environment.
A facile and efficient electrochemical method for sustainable constructing both selanyl phenanthrenes and selanyl polycyclic heteroaromatics (32 examples, 71%-97% yields) through the radical annulation of 2-alkynyl biaryls and 2-heteroaryl-substituted alkynyl benzenes with diselenides at ambient temperature under additive-, chemical oxidant-, catalyst-free and mild conditions was established.
Persulfate-based advanced oxidation processes (AOPs) have obtained increasing attention due to the generation of sulfate radical (SO4•‒) with high reactivity for organic contaminants degradation. Numerous activation methods have been used to activate two common persulfates: peroxymonosulfate (PMS) and peroxydisulfate (PDS). However, the comparisons of activation methods and two oxidants in the comprehensive degradation performance of the target contaminant are still limited. Thus, taking norfloxacin (NOR) as the target contaminant, we proposed five key parameters (the observed pseudo-first-order rate constant, kobs; average mineralization rate, rm; utilization efficiency of catalyst, Ucat; utilization efficiency of oxidant, Uox; and net utilization efficiency of oxidant, Uox') to quantify the comprehensive degradation performance of NOR. The irradiation affected target pollutants, catalysts, and oxidants, leading to an improved degradation performance of NOR. Various heterogeneous catalysts were compared in terms of the key elements contained. Fe, Co, and Mn-based materials performed better, while carbon-based catalysts performed poorly on NOR degradation. The overall degradation performance of NOR was different for PMS and PDS, which can be ascribed to their varied reaction pathways towards NOR, but stemmed from different properties of PMS and PDS. Besides, the effect of pH on the degradation efficiency of NOR was investigated. A neutral solution was optimal for PMS system, while an acidic solution worked better for PDS system. Finally, we analyzed the molecule structure of NOR by density functional theory (DFT) calculation to study the sites easy to attack. Then, we summarized four typical degradation pathways of NOR in SO4•‒-based AOP systems, including defluorination, piperazine ring cleavage, piperazine ring oxidation, and quinoline group transformation.
Photosynthesis [6CO2 + 12H2O → (CH2O)6 + 6O2 + 6H2O] in nature contains a light reaction process for oxygen evolution and a dark reaction process for carbon dioxide (CO2) reduction to carbohydrates, which is of great significance for the survival of living matter. Therefore, for simulating photosynthesis, it is desirable to design and fabricate a bifunctional catalyst for promoting photocatalytic water oxidation and CO2 reduction performances. Herein, a molecular confined synthesis strategy is reasonably proposed and applied, that is the bifunctional CoOx/Co/C-T (T = 700, 800 and 900 ℃) photocatalysts prepared by the pyrolysis of molecular Co-EDTA under N2 and air atmosphere in turn. Among the prepared photocatalysts, the CoOx/Co/C-800 shows the best photocatalytic water oxidation activity with an oxygen yield of 51.2%. In addition, for CO2 reduction reaction, the CO evolution rate of 12.6 µmol/h and selectivity of 75% can be achieved over this catalyst. The improved photocatalytic activities are attributed to the rapid electron transfer between the photosensitizer and the catalyst, which is strongly supported by the current density-voltage (j-V), steady-state and time-resolved photoluminescence spectra (PL). Overall, this work provides a reference for the preparation and optimization of photocatalysts with the capacity for water oxidation and CO2 reduction reactions.
Graphene and its derivatives have sparked intense research interest in wearable temperature sensing due to their excellent electric properties, mechanical flexibility, and good biocompatibility. Despite these advantages, the weak temperature dependence of charge transport makes them difficult to achieve a highly sensitive temperature response, which is one of the remaining bottlenecks in the progress towards practical applications. Unfortunately, detailed knowledge about the key factors of the charge transport temperature dependence in this material that determines the critical performance of electrical sensors is very limited up to now. Here, we reveal that oxygen absorption on the ultrathin reduced graphene oxide (RGO) films (~3 nm) can significantly increase their conductance activation energy over 200% and thus greatly improve the temperature dependence of thermal-activated charge transport. Further investigations suggest that oxygen introduces the deep acceptor states, distributed at an energy level ~0.175 eV from the valence-band maximum, which allows a highly temperature-dependent impurity ionization process and the resulting vast holes release in a wide temperature range. Remarkably, our temperature sensors based on oxygen-doped ultrathin RGO films show a high sensitivity with temperature conductive coefficient of 14.58% K−1, which is one order of magnitude higher than the reported CNT or graphene-based devices. Moreover, the ultrathin thickness and high thermal conductivity of RGO film allow an ultrafast response time of ~86 ms, which represents the best level of temperature sensors based on soft materials. Profiting from these advantages, our sensors show good capacity to identify the slight temperature difference of human body, monitor respiratory rate, and detect the environmental temperature. This work not only represents substantial performance advances in temperature sensing, but also provides a new approach to modulate the charge transport temperature dependence, which could be benefited to both device design and fundamental research.
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