光电化学技术应用于抗氧化分析的研究进展

在新陈代谢过程中, 机体会产生大量以自由基为主要形式的氧化活性物质, 而抗氧化剂可以通过电子转移的方式捕获并中和自由基, 从而有效抵御自由基引起的细胞损害, 以保障和维护人体健康. 食品作为人体外源性抗氧化剂的重要来源可以有效补充因体内代谢及体液排出而损失的抗氧化物质, 因此对食品中抗氧化物质消除自由基的能力即抗氧化能力的测定和评价具有重要意义. 光电化学技术作为一种简单快捷、 低成本、 低背景且高灵敏度的测定方法, 能够有效克服光学法、 色谱法和电化学法等传统测试手段在抗氧化容量分析中的不足. 本文综述了基于半导体及其复合材料的光电化学传感平台的构建及食品体系抗氧化容量分析的研究进展, 评论了多种检测体系的特点并对其研究前景进行了展望.     

超临界二氧化碳偶合超声预处理强化玉米秸秆酶水解(英)

提出了一个木质纤维素生物质预处理的全绿色加工过程.以玉米秸秆和玉米芯为原料,以超临界CO₂和超声偶合法对木质纤维素进行预处理.超临界CO₂预处理条件为:压力15-25 MPa,温度120₁70℃,含水量50%,反应时间0.5₄ h.超声场功率600W,温度80℃,作用时间2-8 h.用纤维素酶水解反应获得的还原糖总量来评价预处理效果.结果表明,单纯超临界CO₂和超临界CO₂偶合超声预处理都能够提高生物质水解反应还原糖产量.对于玉米芯,超临界CO₂预处理（170℃,20 MPa,3 0min）后,还原糖产率为62%（未预处理的为12%）.对于玉米秸秆（170℃,20 MPa,2.5 h）,还原糖产率为46.4%.对于玉米芯,超临界CO₂偶合超声预处理（600 W,80℃下超声处理6 h,然后用170℃,20 MPa超临界CO₂预处理30 min）后,还原糖产率为87%.对于玉米秸秆,超临界CO₂偶合超声预处理（600 W,80℃下超声处理8 h,然后用170℃,20 MPa超临界CO₂预处理1 h）后,还原糖产率为25.5%.与未处理生物质相比,X射线衍射结果表明玉米秸秆和玉米芯在超临界CO₂和超声预处理后其结晶度没有明显变化.扫描电镜分析则发现木质纤维素的表面积显著增加.     

Homogeneous,Low-volume,Efficient, and Sensitive Quantitation of Circulating Exosomal PD-L1 for Cancer Diagnosis and Immunotherapy Response Prediction

Immunotherapy has revolutionized cancer treatment, but its efficacy is severely hindered by the lack of effective predictors. Herein, we developed a homogeneous, low-volume, efficient, and sensitive exosomal programmed death-ligand 1 (PD-L1, a type of transmembrane protein) quantitation method for cancer diagnosis and immunotherapy response prediction (HOLMES-Exo_PD-L1). The method combines a newly evolved aptamer that efficiently binds to PD-L1 with less hindrance by antigen glycosylation than antibody, and homogeneous thermophoresis with a rapid binding kinetic. As a result, HOLMES-Exo_PD-L1 is higher in sensitivity, more rapid in reaction time, and easier to operate than existing enzyme-linked immunosorbent assay (ELISA)-based methods. As a consequence of an outstanding improvement of sensitivity, the level of circulating exosomal PD-L1 detected by HOLMES-Exo_PD-L1 can effectively distinguish cancer patients from healthy volunteers, and for the first time was found to correlate positively with the metastasis of adenocarcinoma. Overall, HOLMES-Exo_PD-L1 brings a fresh approach to exosomal PD-L1 quantitation, offering unprecedented potential for early cancer diagnosis and immunotherapy response prediction.     

A Photowelding Strategy for Conductivity Restoration in Flexible Circuits

Light‐driven micropumps, which are based on electro‐osmosis with the electric field generated by photocatalytic reactions, are among most attractive research topics in chemical micromotors. Until now, research in this field has mainly been focused on the directional motion or collective behavior of microparticles, which lack practical applications. In this study, we have developed a photowelding strategy for repeated photoinduced conductivity recovery of cracked flexible circuits. We immersed the circuit in a suspension of conductive healing particles and applied photoillumination to the crack; photocatalysis of a predeposited pentacene (PEN) layer triggered electro‐osmotic effects to gather conductive particles at the crack, thus leading to conductivity recovery of the circuit. This photowelding strategy is a novel application of light‐driven micropumps and photocatalysis for conductivity restoration.     

Combining magnetic field induced locomotion and supramolecular interaction to micromanipulate glass fibers: toward assembly of complex structures at mesoscale

The formation of ordered complex structures is one of the most challenging fields in the research of biomimic materials because those structures are promising with respect to improving the physical and mechanical properties of man-made materials. In this letter, we have developed a novel approach to fabricating complex structures on the mesoscale by combining magnetic-field-induced locomotion and supramolecular-interaction-assisted immobilization. We have employed a magnetic field to locomote the glass fiber, which was modified by the layer-by-layer self-assembly of magnetic nanoparticles, to desired positions and have exploited the supramolecular interaction to immobilize glass fiber onto the appointed position. By magnetically induced micromanipulation, we can drive another fiber across the former one and finally obtain a crossing structure, which can lead to more complex structures on the mesocale. Moreover, we have constructed a mesoscale structure, termed "CHEM", to demonstrate further the application of this method.     

Highly-efficient photosensitizer based on AIEgen-decorated porphyrin for protein photocleaving

An AIEgen decorated porphyrin(TPETPyP) was easily obtained through a one-step reaction.The bulky TPE in TPETPyP greatly impeded the intermolecular π-π stacking of the porphyrin core,which significantly suppressed aggregation-caused quenching(ACQ) effect of TPETPyP in aqueous solution.The four pyridinium salts formed in TPETPyP also render the whole molecule water solubility,which eliminated its aggregation.TPETPyP exhibited ~1 O_2 quantum yield as high as 0.85 in PBS.Moreover,it also showed high binding affinity to proteins,the major biotarget of ~1 O_2.The high ~1 O_2 quantum yield plus the great binding ability of TPETPyP toward proteins makes it a highly-efficient protein photocleaving agent.Protein electrophoresis experiments demonstrated that TPETPyP can photocleave BSA upon visible light irradiation,indicating that TPETPy P can act as a promising photosensitizer(PS) in PDT.The work here will provide a facile strategy to utilize AIEgens modified traditional PSs for photodynamic therapy(PDT).     

Elasticity‐Dependent Fast Underwater Adhesion Demonstrated by Macroscopic Supramolecular Assembly

Macroscopic supramolecular assembly (MSA) is a recent development in supramolecular chemistry to associate visible building blocks through non‐covalent interactions in a multivalent manner. Although various substrates (e.g. hydrogels, rigid materials) have been used, a general design rule of building blocks in MSA systems and interpretation of the assembly mechanism are lacking and are required. Herein we design three model systems with varied elastic modulus and correlated the MSA probability with the elasticity. Based on the effects of substrate deformability on multivalency, we have proposed an elastic‐modulus‐dependent rule that building blocks below a critical modulus of 2.5 MPa can achieve MSA for the used host/guest system. Moreover, this MSA rule applies well to the design of materials for fast underwater adhesion: Soft substrates (0.5 MPa) can achieve underwater adhesion within 10 s with one order of magnitude higher strength than that of rigid substrates (2.5 MPa).     

Promoting CO2 Electroreduction to Multi-Carbon Products by Hydrophobicity-Induced Electro-Kinetic Retardation

Advancing the performance of the Cu-catalyzed electrochemical CO₂ reduction reaction (CO₂RR) is crucial for its practical applications. Still, the wettable pristine Cu surface often suffers from low exposure to CO₂, reducing the Faradaic efficiencies (FEs) and current densities for multi-carbon (C₂₊) products. Recent studies have proposed that increasing surface availability for CO₂ by cation-exchange ionomers can enhance the C₂₊ product formation rates. However, due to the rapid formation and consumption of *CO, such promotion in reaction kinetics can shorten the residence of *CO whose adsorption determines C₂₊ selectivity, and thus the resulting C₂₊ FEs remain low. Herein, we discover that the electro-kinetic retardation caused by the strong hydrophobicity of quaternary ammonium group-functionalized polynorbornene ionomers can greatly prolong the *CO residence on Cu. This unconventional electro-kinetic effect is demonstrated by the increased Tafel slopes and the decreased sensitivity of *CO coverage change to potentials. As a result, the strongly hydrophobic Cu electrodes exhibit C₂₊ Faradaic efficiencies of ≈90 % at a partial current density of 223 mA cm⁻², more than twice of bare or hydrophilic Cu surfaces.