Hofmeister效应辅助的蛋白质基水凝胶应变传感器

以酪蛋白酸钠和明胶为原料, 通过简单的在硫酸铵溶液中浸泡的方法, 借助Hofmeister效应制备了一种强韧导电的酪蛋白酸钠/明胶水凝胶, 克服了蛋白质基水凝胶柔软、 易碎的问题. 测试结果表明, 该水凝胶具有优异的机械性能, 最大拉伸应力为3.55 MPa, 最大拉伸应变为1375%; 水凝胶的最大电导率为0.0954 S/cm, 导电灵敏因子为0.53. 用该水凝胶制备的传感器对不同大小及不同速率的应变均具有分辨能力, 能够监测人体不同部位的运动, 且传感器的信号传输具有稳定性和准确性, 表明该水凝胶是监测人体健康和运动的理想材料. 该水凝胶还具有良好的形状记忆性能. 这一策略为制备全天然蛋白质基水凝胶开辟了新的思路, 扩展了水凝胶在生物医学和电子传感等相关领域的应用前景.     

聚电解质盐三聚磷酸钠对聚乙烯醇凝胶的Hofmeister效应研究

聚乙烯醇(PVA)物理微晶水凝胶由于化学稳定性好、无毒、生物相容性好等特点,近年来成为物理微晶凝胶研究的模板聚合物。但其力学性能较差,如何提高凝胶的力学性能,拓展其应用范围一直是水凝胶领域的研究难点和热点。Hofmeister盐析效应是提升凝胶力学性能一种高效、绿色的制备手段,但之前的研究多集中在小分子无机盐对凝胶性能的影响,对聚电解质盐的盐析效应鲜见报道。本文研究了三聚磷酸钠(STPP)聚电解质对PVA凝胶性能的影响,系统比较了其与氯化钠及氢氧化钠处理的PVA凝胶;重点从微观形态和结晶结构两方面研究了聚电解质盐与小分子盐引起PVA凝胶的微观结构差异,并分析了结构与性能间的响应关系。聚电解质STPP处理的PVA凝胶薄膜应力达到了23 MPa,应变高达1 100%,断裂韧性(110 MJ/cm³),比纯水凝胶提升55倍之多,并兼具良好的阻燃性能。     

谈分析化学中沉淀效应对化学平衡的影响

谈分析化学中沉淀效应对化学平衡的影响大学化学张士国李红张向东（滨州师专化学系２５６６０４）（辽宁大学化学系沈阳１１００３６）本文对《大学化学》第１１卷第４期发表的题为“分析化学中引入沉淀效应系数的讨论”一文［１］中所提出的分析化学中沉淀效应对化学平衡...     

离子对水结构的影响

液态水中广泛存在的氢键网络使其作为一种结构性很强的液体在自然界中发挥着独一无二的作用。电解质溶于水中后,以水合离子形式存在,离子附近强大的电场使水合层中的偶极水分子发生重排,这些水分子的结构与本体水的结构存在差异。一个多世纪以来,科学家做了大量关于离子对水结构影响的研究。本文从静态谱学和溶剂动力学两方面综述了离子对水结构影响的研究进展,概括了水中氢键的研究情况,并就离子对水结构影响在生物化学方向的重大意义-Hofmeister效应作了解释。     

探究如何更清楚地观察到豆浆的丁达尔效应

豆浆中含有丰富的蛋白质,用红色激光灯在装有新制豆浆的烧杯一侧进行照射,在垂直入射光的方向观察,发现新制豆浆观察不到丁达尔效应。由于分散体系中粒子浓度较大时,粒子产生的散射光会相互干涉而抵消,依次对新制豆浆进行8、20、50、100、200、500、1 000、1 200、1 500、2 000倍的稀释后,重新观察,结果发现:在对豆浆进行2 000倍的稀释后,溶液几乎为无色时,即可以清楚地观察到丁达尔效应。     

铁体系催化剂制备方式对催化活性影响的研究

通过Ｔｙｎｄａｌ效应，电镜观察，电导率测定，结合聚合实验，发现铁体系催化剂在加氢汽油介质中为胶体催化剂，而且是聚结不稳定胶体体系．催化剂各组分配比，加入顺序影响胶粒的形态，因而影响到催化活性与聚合物微观结构．其中较佳配比，较佳加入顺序（Ｆｅ）∶（Ｃｌ）∶（Ａｌ）＝１∶２．５∶２０，催化剂颗粒比较小，均匀，因而比表面积大，催化活性高，相反其他配比的颗粒大，不均匀，催化活性低．陈化使胶粒聚集变大，故催化活性降低．     

离子液体对木瓜蛋白酶催化特性的影响

研究了以1-丁基-3-甲基咪唑、四乙基铵及N-乙基吡啶为阳离子, 配以多种阴离子(H₂PO₄^-, ClO₄^-, HSO₄^-, CH₃COO^-, Cl^-, Br^-, NO₃^-, SCN^-, BF₄^-, PF₆^-)的离子液体对木瓜蛋白酶催化N-苯甲酰-L-精氨酸乙酯(BAEE)水解的活性及热稳定性的影响. 通过分析含离子液体体系中木瓜蛋白酶的水解活性和热力学失活参数, 发现该酶活性及稳定性与离子液体的Kosmotropicity性质无关. 因此, 离子的Hofmeister效应并不适合解释离子液体对木瓜蛋白酶催化特性的影响规律. 当以BF₄^-为阴离子, 改变阳离子结构时, 仅[BMIm][BF₄]可提高酶活性, 其它含官能团的咪唑类离子液体则降低酶活性, 但大部分离子液体明显提高木瓜蛋白酶的热稳定性. 在所研究的离子液体中, 基于PF₆^-或BF₄^-阴离子的离子液体可提高木瓜蛋白酶的活性及其热稳定性. 在含[BMIm][PF₆]介质中, 木瓜蛋白酶的水解活性最高; 在含[HOEtMIm][BF₄]介质中其热稳定性最好.     

富稀土金针菇对小鼠生物效应的影响

本研究进行富稀土金针菇和农用硝酸稀土对小鼠生长、发育及耐力的对比试验。结果表明，饲喂富稀土金针菇的小鼠，三周后体脏重及耐力均显著高于无稀土的金针菇对照组（Ｅ组），且表现出一定的剂量效应。与饲喂硝酸稀土的小鼠（Ｄ组）相比，当添加的稀土量相等时，饲喂富稀土金针菇的小鼠（Ｂ组）体重和脏器重明显增加，游泳时间延长２８．６％，游泳后Ｂ组血乳酸含量的变化明显低于Ｃ、Ｄ、Ｅ组，血糖含量下降率较小。可见，将适量富     

钒化合物生物效应的化学基础和药用前景金属药物研究的化学问题

本文从非必需元素的相似性作用规律的观点，综述了钒在生理条件下的物种变化和决定其生物效应的基本化学性质，对钒化合物的类胰岛素活性、作用机制和钒抗糖尿病药物研究进行了介绍。     

离子对水的17O-NMR化学位移和水结构的影响

在小于1 mol•L-1的浓度范围内,测试了碱金属、碱土金属氯化物、卤化钠及其它常见含氧酸盐溶液的17O-NMR化学位移（δ(H217O)）.发现离子对δ(H217O)的影响与离子的半径、电荷、离子外层电子结构及离子结构有关.其它离子参数相同时,离子半径越大,离子的摩尔δ(H217O)越大;在电子结构相同的情况下,离子电荷越大,离子的摩尔δ(H217O)越大;多原子离子的摩尔δ(H217O)更多地是与其离子结构相关.离子的摩尔δ(H217O)的大小反映了该离子对水的结构的影响情况,离子的摩尔δ(H217O)越大,对水的结构促进作用越强.     

Anion Complexation and The Hofmeister Effect

The ¹H NMR spectroscopic analysis of the binding of the ClO₄^? anion to the hydrophobic, concave binding site of a deep‐cavity cavitand is presented. The strength of association between the host and the ClO₄^? anion is controlled by both the nature and concentration of co‐salts in a manner that follows the Hofmeister series. A model that partitions this trend into the competitive binding of the co‐salt anion to the hydrophobic pocket of the host and counterion binding to its external carboxylate groups successfully accounts for the observed changes in ClO₄^? affinity.     

Hofmeister Effect on Thermo-responsive Poly(N-isopropylacrylamide)Hydrogels Grafted on Macroporous Poly(vinyl alcohol) Formaldehyde Sponges

In this work,the Hofmeister effects of nine kinds of anions at different concentrations on the lower critical solution temperature(LCST)of the macroporous thermo-responsive poly(N-isopropylacrylamide)grafted poly(vinyl alcohol)formaldehyde(PVF-g-PNIPAM)hydrogels are investigated with differential scanning calorimetry(DSC).Four kinds of anions with strong hydration,including CO3^2–,SO4^2–,S2 O3^2–,and F^–,and four kinds of anions with weak hydration,including Br^–,NO3^–,I^–,and ClO4^–,and Cl^–as a medium anion are systematically studied and found to demonstrate the effects of the residual hydroxyl groups and network structure of PVF on the LCST values of PVF-g-PNIPAM hydrogels in comparison with that of neat PNIPAM.On the one hand,the existence of hydroxyl groups on PVF backbone promotes the solubility of grafted PNIPAM due to their hydrophilicity and hydrogen-bond interactions with water.On the other hand,the network structure of as-prepared samples restricts free movements of grafted PNIPAM chains,which results in the increase of LCST values.In addition,the difference of grafting percentage also influences the variation of LCST values of PVF-g-PNIPAM hydrogels under salt concentration.     

Unprecedented tunable hydrophobic effect and anion recognition triggered by AIE with Hofmeister series in water

An unprecedented tunable hydrophobic effect in self-assembly of a small cationic organic fluorophore(NI-TPy~+)-based with aggregation-induced emission(AIE) property was realized in aqueous solution.The amplification of hydrophobicity was found to be significantly dependent upon the increasing aggregate s of NI-TPy~+,which enable d the study of the hydrophobic binding of chaotropic anions with the Hofmeister series.     

Rational Design of Heat‐Set and Specific‐Ion‐Responsive Supramolecular Hydrogels Based on the Hofmeister Effect

Smart supramolecular hydrogels have been prepared from a bolaamphiphilic L ‐valine derivative in aqueous solutions of different salts. The hydrogels respond selectively to different ions and are either reinforced or weakened. In one case, in contrast to conventional systems, the hydrogels are formed upon heating of the system. The use of the hydrogels in the controlled release of an entrapped dye is described as a proof of the potential applications of these systems. The responsive hydrogels were rationally designed by taking into account the noticeable effect of different ions from the Hofmeister series in the solubility of the hydrogelator, which was assessed by using NMR experiments. On the one hand, kosmotropic anions such as sulfate produce a remarkable solubility decrease in the gelator, which is associated with gel reinforcement, as measured by rheological experiments. On the other hand, chaotropic species such as perchlorate weaken the gel. A dramatic effect was observed in the presence of guanidinium chloride, which boosted the solubility of the gelator, in accordance with its chaotropic behaviour reported in protein science. In this case, a direct interaction of the guanidinium species with the carbonyl groups of the hydrogelator is detected by ¹³C NMR spectroscopy. The weakening of this interaction upon a temperature increase allows for the preparation of heat‐set hydrogelating systems.     

Hofmeister Effects of Group II Cations as Seen in the Unfolding of Ribonuclease A

This work studies the effects of alkaline-earth cation addition on the unfolding free energy of a model protein, pancreatic Ribonuclease A (RNase A) by differential scanning calorimetry analysis. RNase A was chosen because: a) it does not specifically bind Mg²⁺, Ca²⁺ and Sr²⁺ cations and b) maintains its structural integrity throughout a large pH range. We have measured and compared the effects of NaCl, MgCl₂, CaCl₂ and SrCl₂ addition on the melting point of RNase A. Our results show that even though the addition of group II cations to aqueous solvent reduces the solubility of nonpolar residues (and enhances the hydrophobic effect), their interactions with the amide moieties are strong enough to “salt-them-in” the solvent, thereby causing an overall protein stability reduction. We demonstrate that the amide-cation interactions are a major contributor to the observed “Hofmeister Effects” of group II cations in protein folding. Our analysis suggests that protein folding “Hofmeister Effects” of group II cations, are mostly the aggregate sum of how cation addition simultaneously salts-out hydrophobic moieties by increasing the cavitation free energy, while promoting the salting-in of amide moieties through contact pair formation.     

Ordered Large-Pore MesoMOFs Based on Synergistic Effects of TriBlock Polymer and Hofmeister Ion

Ordered mesoporous metal–organic frameworks (mesoMOFs) were constructed with a uniform pore size up to about 10 nm and thick microporous walls, opening up the possibility for the mass diffusion of large-size molecules through crystalline MOFs. The synergistic effects based on triblock copolymer templates and the Hofmeister salting-in anions promote the nucleation of stable MOFs in aqueous phase and the in situ crystallization of MOFs around templates, rendering the generation of a microcrystal with periodically arranged large mesopores. The improved mass transfer benefiting from large-pore channels, together with robust microporous crystalline structure, endows them as an ideal nanoreactor for the highly efficient digestion of various biogenic proteins. This strategy could set a guideline for the rational design of new ordered large-pore mesoMOFs with a variety of compositions and functionalities and pave a way for their potential applications with biomacromolecules.     

Synergy between Hofmeister effect and coupled water in proteins: Unusual dilational moduli of BSA at air/solution interface

This study relates interfacial interactions of bovine serum albumin (BSA) molecules in dilute solutions with its dilatational rheology. Dynamic surface tension and the associated dilational elastic modulus and viscosity for BSA and mixtures of BSA with Hofmeister electrolytes—NaCl, NaClO₄, Na₂SO₄, NaF and Na₂HPO₄ have been studied using a sinusoidal surface compression and expansion for frequencies ranging from 0.01 to 0.4 Hz. at solution/air interface. In all the BSA + electrolyte systems, both the elastic modulus and viscosity show unusually high values compared with pure BSA or pure electrolytes. In the presence of NaF and Na₂SO₄ the viscosity of protein increases almost by 50–80-fold and the corresponding elastic modulus also changes by 30–50-fold. Hydrated Hofmeister ions surely influence the measured rheological properties. In addition, the synergistic effect of the hydrated protein and the vicinal hydrated electrolytes possibly contribute to the high viscosity and elasticity due to change in dynamics of these assemblies. Thus the behavior of BSA is effected by salts in different ways, especially due to the dynamics and strength of the water molecules in the assembly.     

Ordered Large‐Pore MesoMOFs Based on Synergistic Effects of TriBlock Polymer and Hofmeister Ion

Ordered mesoporous metal–organic frameworks (mesoMOFs) were constructed with a uniform pore size up to about 10 nm and thick microporous walls, opening up the possibility for the mass diffusion of large‐size molecules through crystalline MOFs. The synergistic effects based on triblock copolymer templates and the Hofmeister salting‐in anions promote the nucleation of stable MOFs in aqueous phase and the in situ crystallization of MOFs around templates, rendering the generation of a microcrystal with periodically arranged large mesopores. The improved mass transfer benefiting from large‐pore channels, together with robust microporous crystalline structure, endows them as an ideal nanoreactor for the highly efficient digestion of various biogenic proteins. This strategy could set a guideline for the rational design of new ordered large‐pore mesoMOFs with a variety of compositions and functionalities and pave a way for their potential applications with biomacromolecules.     

介观化学体系中的动力学尺度效应

以生命和表面催化体系为对象,研究了介观化学体系中内涨落对体系非线性动力学行为的调控作用。内涨落可以诱导随机振荡,其强度在体系处于最佳尺度时会出现一个甚至多个极大值,并且在耦合体系中会得到进一步增强,表现为尺度共振效应、尺度选择效应和双重尺度效应,揭示了介观化学体系中尺度效应的新机制。