Special Pore-Space-Partition CoFePBA Hollow Framework Realizing High-Performance Glucose Sensing

In this work for the first time pore-space-partition (PSP)-CoFePBA hollow framework is elaborately designed and successfully obtained via self-template internal dissolution strategy. As is demonstrated by our previous report, Prussian blue analogue (PBA) with hollow morphology is very beneficial to improve sensing performance. As expected, the PSP-CoFePBA hollow framework in this work exhibits far superior glucose sensing performance compared with classic CoFePBA nanoparticles and nanoboxes as well as most of reported PBA-based glucose sensors. Herein, very high sensitivity of 1184.18 μA mM⁻¹ cm⁻² and 267.63 μA mM⁻¹ cm⁻² in the concentration range of 5–325 μM and 325–1025 μM, respectively, as well as low detection limit of 0.4 μM (S/N=3) and high stability can be observed. In a word, this work proposes and develops a simple and general synthetic strategy for constructing PBA-based hollow material, that will be very helpful in this field.     

Anchoring a Structurally Editable Proximal Cofactor-like Module to Construct an Artificial Dual-center Peroxygenase

A recent novel strategy for constructing artificial metalloenzymes (ArMs) that target new-to-nature functions uses dual-functional small molecules (DFSMs) with catalytic and anchoring groups for converting P450BM3 monooxygenase into a peroxygenase. However, this process requires excess DFSMs (1000 equivalent of P450) owing to their low binding affinity for P450, thus severely limiting its practical application. Herein, structural optimization of the DFSM-anchoring group considerably enhanced their binding affinity by three orders of magnitude (K_d≈10⁻⁸ M), thus approximating native cofactors, such as FMN or FAD in flavoenzymes. An artificial cofactor-driven peroxygenase was thus constructed. The co-crystal structure of P450BM3 bound to a DFSM clearly revealed a precatalytic state in which the DFSM participates in H₂O₂ activation, thus facilitating peroxygenase activity. Moreover, the increased binding affinity substantially decreases the DFSM load to as low as 2 equivalents of P450, while maintaining increased activity. Furthermore, replacement of catalytic groups showed disparate selectivity and activity for various substrates. This study provides an unprecedented approach for assembling ArMs by binding editable organic cofactors as a co-catalytic center, thereby increasing the catalytic promiscuity of P450 enzymes.     

Side-Chain Chemistry Governs Hierarchical Order of Charge-Complementary β-sheet Peptide Coassemblies

Self-assembly of proteinaceous biomolecules into functional materials with ordered structures that span length scales is common in nature yet remains a challenge with designer peptides under ambient conditions. This report demonstrates how charged side-chain chemistry affects the hierarchical co-assembly of a family of charge-complementary β-sheet-forming peptide pairs known as CATCH(X+/Y−) at physiologic pH and ionic strength in water. In a concentration-dependent manner, the CATCH(6K+) (Ac-KQKFKFKFKQK-Am) and CATCH(6D−) (Ac-DQDFDFDFDQD-Am) pair formed either β-sheet-rich microspheres or β-sheet-rich gels with a micron-scale plate-like morphology, which were not observed with other CATCH(X+/Y−) pairs. This hierarchical order was disrupted by replacing D with E, which increased fibril twisting. Replacing K with R, or mutating the N- and C-terminal amino acids in CATCH(6K+) and CATCH(6D−) to Qs, increased observed co-assembly kinetics, which also disrupted hierarchical order. Due to the ambient assembly conditions, active CATCH(6K+)-green fluorescent protein fusions could be incorporated into the β-sheet plates and microspheres formed by the CATCH(6K+/6D−) pair, demonstrating the potential to endow functionality.     

四氯化钼催化丁二烯1,2-聚合体系的紫外可见光谱研究

对四价钼系催化丁二烯1,2-聚合中Mo(Ⅳ)络合物的紫外可见光谱进行了研究.MoCl₄乙酸乙酯溶液呈棕红色,显顺磁性.在光谱的紫区和红区共有3个自旋允许d-d跃迁吸收带.Mo(Ⅳ)八面体络合物上各种配体的交换对光谱吸收带位置无影响.Mo(Ⅳ)在512nm处的特征吸收带随Al(i-Bu)₃/Mo或Al(i-Bu)₂OPh/Mo增加而渐趋消失,这是Mo(Ⅳ)→Mo(Ⅲ)反应的标志.在MoCl_4-n·(OC₈H₁₇)_n-Bd-Al(i-Bu)₂OPh₃组分陈化体系中Mo(Ⅳ)的还原得到加快,催化聚合活性亦有提高。     

Trithia- and dithiaselenapentalenes from benzylidene-1,2-dithioles and heterocumulenes

Deprotonation of the 5-aryl-3-benzyl-1λ⁴,2-dithiol-1-ylium iodides ( 6a–6d ) obtained by reaction of the 1-aryl-4-phenylbutan-1,3-diones ( 5a–5d ) with hydrogen sulfide and iodine in ethanol gave the stable 5-aryl-3-benzylidene-3H-1,2-dithioles ( 3a–3d ), respectively. The dithioles ( 3a–3d ) underwent thermal cycloaddition reactions with isoselenocyanates and isothiocyanates to give the 2-(substituted amino)-5-aryl-3-phenyl-6,6aλ⁴-dithia-1-selenapentalenes ( 7a–7h ) andthe 2-(substituted amino)-5-aryl-3-phenyl-1,6,6aλ⁴-trithiapentalenes ( 8a–8l ), respectively. The dithioles( 3a–3d ) reacted with isocyanates to give the N-substi-tuted-2-phenyl-2-(5-aryl-3H-1,2-dithiol-3-ylidene) acetamides ( 11a–11h ). © 1997 John Wiley & Sons, Inc. Heteroatom Chem 8 : 233–244, 1997.     

A novel synthesis of acrylic acid containing polymers

A novel synthesis of linear acrylic acid containing polymers, poly(styrene-co-acrylic acid) and poly(acrylic acid), was accomplished through hydrolysis of the respective parent polymers, i.e. poly(styrene-co-methyl acrylate) and poly(methyl acrylate), with trimethylsilyl iodide under mild conditions. Combination of ¹H NMR, ¹³C NMR, FTIR, DSC and chemical titration confirms that the conversion from methoxycarbonyl to carboxyl is almost complete. This method is further successfully applied to synthesize poly-(ethyl methacrylate-co-acrylic acid) through selective hydrolysis of the methyl acrylate units in poly(ethyl methacrylate-co-methyl acrylate).     

溴酸钾氧化吡口罗红G催化动力学光度法测定痕量NO-2

研究了在磷酸介质中亚硝酸根催化溴酸钾氧化吡口罗红Ｇ而使其褪色，建立了催化动力学光度法测定痕量亚硝酸根的新方法，测定范围为０．２～２０μｇ／ｍＬ，检出限为０．２ｎｇ／ｍＬ，用于食品和水样中的亚硝酸根测定获得满意结果     

火焰原子吸收光谱法测定人发中镁时工作条件对干扰影响的研究

研究了用ＨＮＯ３－ＨＣｌＯ４湿法消化样品，火焰原子吸收法测定人发中镁时工作条件对干扰的影响，在测量高度为１２ｍｍ，乙炔流量为１．０Ｌ／ｍｉｎ时，可以不加释放剂而直接测定镁。标准加入回收率为９６％￣１０５％，相对标准偏差为３．０％。     

Metal-organic framework as a multi-component sensor for detection of Fe3+, ascorbic acid and acid phosphatase

In this research,a hydroxyl group functionalized metal-organic framework(MOF),UiO-66-(OH)₂,was synthesized as a "on-off-on" fluore scent switching nanoprobe for highly sensitive and selective detection of Fe³⁺,ascorbic acid(AA) and acid phosphatase(ACP).UiO-66-(OH)₂ emits yellow-green light under ultraviolet light,when Fe³⁺ was added,Fe³⁺ was chelated with hydroxyl group,the electrons in the excited state S_1 of the MOF transferred to the half-filled 3 d orbits of Fe³⁺,resulting in fluorescence quenching because of the nonradiative electron/hole recombination annihilation.AA could reduce Fe³⁺ to Fe²⁺,which can destroy the electron transfer between UiO-66-(OH)₂ and Fe³⁺ after AA adding,resulted in nonoccurrence of the nonradiative electron transfer,leading to the recovery of UiO-66-(OH)₂ fluorescence intensity.The probe can also be used to detect ACP based on the enzymolysis of 2-phospho-L-ascorbic acid(AAP) to produce AA.Benefitting from the hydroxyl group and the characteristics of UiO-66,including the high porosity and large surface area,the developed UiO-66-(OH)₂ showed extensive advantages as a fluorescent probe for detection of multi-component,such as high sensitivity and selectivity,colorimetric detection,fast response kinetics and easy to operate,economical and secure.This is the first time to use active group functionalized MOFs as a multicomponent sensor for these three substances detection.     

Super-assembled highly compressible and flexible cellulose aerogels for methylene blue removal from water

Physical adsorption is a common method to solve the contamination of methylene blue in dyeing wastewater. As a kind of adsorption material, cellulose aerogels with high porosity and surface areas have great potential application in methylene blue removal. However, the week hydrogen bonding between cellulose nanofibers making the cellulose aerogels with the poor mechanical properties and can be easily destroyed during adsorption. Hence, the preparation of cellulose aerogels with high mechanical strength is still a great challenge. Here, we report a robust super-assembly strategy to fabricate cellulose aerogels by combining cellulose nanofibers with PVA and M-K10. The resulting cellulose aerogels not only has a robust chemically cross-linked network, but also has strong H-bonds, which greatly enhance the mechanical properties. The resulting cellulose aerogels possess a low density of 19.32 mg/cm3.Furthermore, the cellulose aerogel shows 93% shape recovery under 60% strain(9.5 k Pa under 60% strain)after 100 cycles, showing excellent mechanical property. The adsorption capacity of cellulose aerogel to methylene blue solution of 20 mg/L is 2.28 mg/g and the adsorption kinetics and adsorption isotherms have also been studied. Pseudo-second-order kinetic model and Freundlich isotherm model are more acceptable for indicating the adsorption process of methylene blue on the cellulose aerogel. Thus, this compressible and durable cellulose aerogel is a very prospective material for dyeing wastewater cleanup.