Amperometric Detection of Catecholamine Neurotransmitters Using Electrocatalytic Substrate Recycling at a Laccase Electrode

An enzyme electrode based on the coimmobilization of an osmium redox polymer and laccase on glassy carbon electrodes has been applied to ultra sensitive amperometric detection of the catecholamine neurotransmitters dopamine, epinephrine and norepinephrine, resulting in nanomolar detection limits, as low as 4 nM for dopamine. The sensitivity of the electrode is due to signal amplification via oxidation of the catecholamine by the immobilized laccase, which is regenerated by concomitant reduction of oxygen to water, coupled to the electrocatalytic re‐reduction of the oxidized catecholamine by the osmium redox complex: electrocatalytic substrate recycling. In addition because the sensor can be operated in reductive mode at ?0.2 V (vs. Ag/AgCl), noise and interferences are diminished. Combined with its high sensitivity this enzyme electrode also exhibited excellent selectivity allowing the detection of catecholamines in the presence of ascorbic acid. However, differentiation between the current responses achieved for the three catecholamines is not possible. The effective mode of constant recycling, resulting in amplification of the current response, of the laccase enzyme electrode sensor combined with the inherent advantages of using electrochemical techniques holds great promise for the future of catecholamine detection and monitoring.     

Mitochondria targeted cancer therapy using ethidium derivatives

In this study, we reported on two novel fluorescent ethidium derivatives of MTP1 and MTP2 for selective and efficient cancer therapy. MTP1 and MTP2 exhibited cancer cell targeting and subsequent mitochondria targeting and imaging abilities. Moreover, both MTP1 and MTP2 would induce mitochondria depolarization and so along with a series of cascaded biochemical effects including the reduction of ATP production, destruction of intracellular redox potential balance and release of mitochondria cytochrome C (Cyt C), which could finally trigger caspase-dependent cell apoptosis. More interestingly, both MTP1 and MTP2 demonstrated significant cancer suppression abilities in vitro and in vivo, which presented a new paradigm for the development of unique anti-cancer agent candidates in precise and efficient cancer theranostics.     

SO·4-自由基氧化酪氨酸反应中的溶剂效应

研究了水-乙腈混合溶液中SO·4-自由基氧化酪氨酸的反应.实验结果表明,SO·4-自由基氧化酪氨酸的反应机制不因乙腈的加入而改变,但所产生的瞬态粒子的动力学行为受到较大影响.随介质中乙腈体积分数的增加,SO·4-的衰变速率减慢而酪氨酸中性自由基(TyrO·)的衰变速率加快.我们认为这两种自由基所呈现出来的相反的溶剂效应是由于其所带电荷的不同.随介质中乙腈体积分数的增加,SO·4-氧化酪氨酸的反应速率减慢.这一实验结果意味着,在有机溶剂存在的情况下TyrO·/TyrOH的氧化还原电势可能发生了变化,从而旁证了关于TyrO·/TyrOH的氧化还原电势因酪氨酸从游离状态变到肽或蛋白质中而发生变化的推测.     

Redox deracemization of α-substituted 1,3-dihydroisobenzofurans

Chiral α-substituted 1,3-dihydroisobenzofurans are key scaffolds in a number of bioactive natural products and synthetic pharmaceuticals. However, catalytic asymmetric approaches have been rarely developed. Here, a redox deracemization technology is adopted to address the catalytic asymmetric synthesis. A broad range of α-aryl substituted 1,3-dihydroisobenzofurans are effectively deracemized in high efficiency with excellent ee. α-Alkynyl substituted ethers were also compatible with the deracemization technology.     

A dynamic systems model of dyadic interaction

We develop a differential equation model of dyadic interaction that embodies the basic assumption that members of intimate couples form an interactive system in which the behavior of each member of a couple is influenced by the other's behavior and by goals that each person has for herself or himself. The dynamic solutions of this system suggest that when each person in the dyad is “cooperative”, then an equilibrium can be approached. The equilibrium represents a compromise position between the individuals’ own ideals and those of the partner. On the other hand, if one individual, or both, is uncooperative, then this system often, but not always, becomes unstable. One paradoxical deduction from the model is that, through mutual cooperation, couples can experience periods of stability, but such stable situations are not necessarily satisfying.     

Combining electrolysis with thermocatalysis for dry reforming of methane in a naturally stratifying liquid alloy-salt catalytic system

Dry reforming of methane (CH₄) with carbon dioxide (CO₂) is an attractive technology for producing value-added syngas and mitigating greenhouse gas emission. However, this process usually requires high energy input due to the intrinsic inertness of CH₄ and CO₂. Besides, the widely investigated solid Ni-based catalysts typically suffer from coking and sintering issues, leading to degradation in catalytic performance. Liquid alloys and molten salts are emerging as promising catalytic materials for CH₄ dry reforming. In this work, we combine electrolysis with thermocatalysis for CH₄ dry reforming in a naturally stratifying liquid alloy-salt system, which achieves effective and stable catalytic performance under relatively mild operation conditions. The conversions of CH₄ and CO₂ reach 37% and 95%, respectively, in a bubble column reactor comprising Ni–Bi alloy and LiNaCO₃ during constant current electrolysis at 1.5 A and 900 °C. The selectivities of H₂ and CO were maintained at 85% and 92%, respectively. Ab initio molecular dynamics simulation shows that the oxides of both Ni and Bi promote the C–H bond dissociation. Therefore, the electrochemical process combine electrolysis with thermocatalysis in the liquid alloy-salt system represents a promising approach to achieving effective and stable CH₄ dry reforming.     

Geometrically Constrained Organoboron Species as Lewis Superacids and Organic Superbases

This report unveils an advancement in the formation of a Lewis superacid (LSA) and an organic superbase by the geometrical deformation of an organoboron species towards a T-shaped geometry. The boron dication [ 2 ]²⁺ supported by an amido diphosphine pincer ligand features both a large fluoride ion affinity (FIA>SbF₅) and hydride ion affinity (HIA>B(C₆F₅)₃), which qualifies it as both a hard and soft LSA. The unusual Lewis acidic properties of [ 2 ]²⁺ are further showcased by its ability to abstract hydride and fluoride from Et₃SiH and AgSbF₆ respectively, and effectively catalyze the hydrodefluorination, defluorination/arylation, as well as reduction of carbonyl compounds. One and two-electron reduction of [ 2 ]²⁺ affords stable boron radical cation [ 2 ]⋅⁺ and borylene 2 , respectively. The former species has an extremely high spin density of 0.798e at the boron atom, whereas the latter compound has been demonstrated to be a strong organic base (calcd. pK_BH⁺ (MeCN)=47.4) by both theoretical and experimental assessment. Overall, these results demonstrate the strong ability of geometric constraining to empower the central boron atom.     

On the Electrochemical Behaviour of Some 2,3-Dihydrothiazolo[3,2-a]Benzimidazol-3-One and 1-Ethylmercapto-3(4H)-Isoquinolones Derivatives

The electrochemical behaviour of several derivatives containing the sequence S-C-CO-N in their structure presented as such or in masked form in both aqueous and non-aqueous media are reported. The results of electrooxidation indicated that when the S atom is present as hetero atom in the structure of the molecule the main product will be the sulphone derivative, on the other hand when present in the form C=S the preferential product is the dimer. The overall redox study indicated that the azo group at C-2 is very active in both aqueous and non aqueous media. On the other hand derivatives substituted at C-2 the preferential electrochemical step is the attack of the hetero ring itself.     

Designing High-Donicity Anions for Rechargeable Potassium Superoxide/Peroxide Batteries

A battery cathode based on the superoxide/peroxide redox not only inherits the advantage of oxygen (O₂) batteries in high capacities and low costs but also overcomes the disadvantages in O₂ storage, electrolyte evaporation, and anode deactivation due to O₂ crossover. Herein, we report an enhanced potassium superoxide (KO₂)/peroxide (K₂O₂) conversion by adopting a high-donicity anion additive in the ether-based electrolyte. Such an anion was synthesized via a “Solvent-in-Anion” strategy and validated to enhance the electron donicity of the electrolyte. The use of high-donicity anion could lead to enhanced KO₂ utilization (≈90.2 %) by retarding electrode passivation and allow the full charging back of K₂O₂ through the solution-mediated pathway without electrocatalysts. No apparent cell degradation is observed during the first 120 cycles by controlling the reversible depth-of-discharge capacity at 292 mAh g⁻¹ within an O₂-free region. The K−KO₂ cell delivers a high energy efficiency (>84.4 %) and a lifespan of over 1440 hours.     

Targeted Management of Perovskite Film by Co(II) Sulfophenyl Porphyrin for Efficient and Stable Solar Cells†

In the lead halide perovskite solar cells (PSCs), the redox reaction of I^– and Pb²⁺ ions in perovskite materials under the fabrication and operation processes causes the formation of defects to destroy the cell efficiency and long-term stability. Herein, we have employed a Co(II) sulfophenyl porphyrin (CoTPPS) to modify the perovskite film. The sulfonic group could coordinate with Pb²⁺ to efficiently passivate the uncoordinated Pb²⁺. Additionally, Co²⁺ ions in CoTPPS could react with I₂ generated under the thermal and light stress to yield the Co³⁺ and I^–, thus achieving the regeneration of I^– in perovskite film. Therefore, the CoTPPS could realize the targeted management of the imperfections in perovskite film. As a result, the modified PSCs reveal the remarkably enhanced cell performance. More importantly, the CoTPPS modified device retains 75% of its initial efficiency value storing at 85°C for 2000 h and about 70% of its efficiency when being continuously illuminated at a simulated sunlight for 1200 h. This strategy tackles the chemical reaction and inhibits the defect generation, thus improving the operational stability and efficiency of PSCs.