Can coacervation unify disparate hypotheses in the origin of cellular life?

Here, we review the recent progress in the characterisation and utilisation of coacervates as protocell models in the origin of life studies. We provide evidence that coacervation could have played a unique role during the origin of life, based on its ability to form from a range of different prebiotically relevant molecules; partition solutes; support and alter RNA catalysis and readily deform its shape. We discuss how these properties could have been important for the formation of the first membrane-bound cells, supporting RNA-peptide evolution and primitive metabolism, and in replicating and proliferating by growth and division processes.     

聚羟基丁酸酯共聚物超薄膜中向日葵晶形成的原子力显微镜观察

低维数下的高分子(如在二维薄膜或一维管道及孔洞中)的各种行为由于更加触及高分子的动力学、热力学本质而逐渐成为高分子科学研究的热点之一．实验表明,薄膜中聚合物的玻璃化转变温度、结晶动力学及形貌等与本体有很大的偏离．我们先前的研究结果表明,在基板的作用下,共混物薄膜的相形态会发生逆转;     

微乳液析相液-液萃取分光光度法测定铝

建立了TritonX100微乳液析相液液萃取法测定铝的新体系。在VTritonX100∶V正丁醇∶V正庚烷∶V水=2.7∶15∶1.5∶4微乳液介质中,铝水杨基荧光酮于72℃水浴中加热15min即被富集于微乳液层中。最大吸收波长为540nm,铝含量在0～0.5mg·L-1范围内符合比耳定律,表观摩尔吸收系数为4.3×105L·mol-1·cm-1。方法用于食品中铝的测定,结果满意。     

多相高分子体系中的粘弹相分离行为

相分离广泛存在于各种凝聚态物质中.根据局部浓度的变化形式,可将相分离分为固体模型(model B)和流体模型(model H),这两种模型适用于动力学对称的体系.近年来,Tanaka发现在一些动力学不对称的多组分高分子体系里存在一种新的相分离模式,其相分离过程分为动力学过程可用一个普适的粘弹模型来进行描述.动力学不对称可由体系中两组分间大的尺寸差异或玻璃化温度差异引起.本文介绍了多相高分子体系中产生粘弹相分离的原理及其基本特征,并讨论了模量、粘度、填料等因素对粘弹相分离动力学过程及多相体系微观结构的影响.     

热致相分离法偏二氯乙烯-氯乙烯共聚物多孔膜的制备及性能

以偏二氯乙烯-氯乙烯共聚物[P(VDC-co-VC)]为成膜聚合物, 邻苯二甲酸二甲酯(DMP)为稀释剂, 采用热致相分离(TIPS)法制备了具有多孔结构的P(VDC-co-VC)膜. 通过聚合物-稀释剂二元体系相图、 场发射扫描电镜(FESEM)、 差示扫描量热仪(DSC)、 X射线衍射(XRD)、 原子力显微镜(AFM)、 纯水通量、 接触角、 孔径及其分布、 截留率及力学性能等研究了聚合物含量对P(VDC-co-VC)多孔膜结构和性能的影响. 结果表明, P(VDC-co-VC)-DMP二元体系成膜过程以液-液(L-L)分相为主, 随着聚合物含量增加, 膜的横截面由类花瓣状结构向胞腔状结构转变, 膜的孔连通性降低, 结构变得较为致密, 同时膜上表面孔隙率降低, 粗糙度增大. L-L分相时间和聚合物含量的变化, 导致膜结晶度先降低后增大. 聚合物含量的增加使膜上表面接触角、 断裂强度及蛋白截留率增加, 但膜的平均孔径、 孔隙率及纯水通量先增加后减小. 当聚合物质量分数为30%时, 所得膜通透性较优, 断裂强度可达7.5 MPa.     

Polyhydroxyl-based surfactants and their physico-chemical properties and applications

This contribution deals with the physical-chemical properties of surfactants carrying hydroxyl groups in the polar part. Topics discussed include surface and colloid properties, micelles (both single and multi-component), general phase behaviour and microemulsions. A general conclusion is that our understanding of polyhydroxy surfactants is increasing, but that further work is needed to unravel certain aspects of this important class of surfactants. Examples of such aspects are the origin of the liquid-liquid phase separation and the adsorption to solid surfaces of polyhydroxy surfactants.     

晶状体蛋白识别互作与白内障的研究进展

白内障是全球致盲率最高的眼科疾病, 发病组织为晶状体. 晶状体内纤维细胞含有高浓度的晶状体蛋白, 晶状体蛋白家族分α?, β?和γ?3大亚家族. α-晶状体蛋白具有小分子伴侣功能, 可识别错误折叠蛋白质, 维持晶状体内蛋白质稳态; β?/γ?晶状体蛋白通过分子内或分子间相互作用, 主要发挥结构蛋白功能. 晶状体蛋白在晶状体纤维细胞内呈瞬时有序排列, 精准分子识别及动态相互作用在维持晶状体透明度中发挥关键作用. 晶状体内蛋白质稳态失衡是白内障的主要致病因素. 晶状体蛋白半衰期长, 且翻译合成后不再更新, 广泛受pH值、 金属离子、 辐射损伤和蛋白质翻译后修饰等细胞内外环境因素和化学因素的干扰, 影响晶状体蛋白间的分子识别和相互作用, 诱发白内障. 理清化学调控的晶状体蛋白分子识别及互作调控, 有助于阐明白内障发病机理, 并发掘防治白内障的创新策略. 本文基于晶状体蛋白识别互作与白内障研究进展, 综合评述了晶状体蛋白的分子识别、 相互作用方式、 调控因素及研究技术创新, 并探讨了晶状体蛋白识别互作调控网络在白内障药物研发的应用价值与挑战.     

凝聚体及其在人造细胞领域中的应用

生命起源问题一直受到科研工作者的广泛关注,合成生物学家致力于构建较为简单且在原始地球条件下合理的隔室体系来模拟原始细胞.凝聚体是聚合物间静电相互作用所产生的的相分离体系,是一种可能的原始细胞结构,广泛应用于人造细胞的构建.同时,目前很多研究发现这种凝聚体在细胞内构成多种亚细胞器结构,因此对于凝聚体作为人造细胞器的研究也...     

Coating and fusing cell membranes onto a silica surface and their chromatographic characteristics

Summary A new cell membrane stationary phase (CMSP) consisting of porous silica coated with active cell membranes is presented for affinity chromatography. By immersing, silica into a suspension of cell membranes, the whole surface of silica was covered by the cell membranes due to the irreversible adsorption of silanol groups (Si−OH) on the silica surface and the self-fusion of the cell membranes. CMSP can be used directly as a chromatographic packing material without any additional chemical modification. The surface characteristics, enzymatic activity, and chromatographic behavior of CMSP were investigated. The results obtained from scanning electron microscope, surface energy spectrometer, enzyme assay, and liquid chromatography showed that the surface characteristics of CMSP were very different from that of normal and reversed stationary phases. CMSP was found to have the characteristics of both cell membrane activity and chromatographic separation. Moreover, CMSP, as a chiral stationary phase, could be used for the enantiomeric separation of (±) Bay-K8644. The capacity factor of some calcium antagonists on CMSP was found to have a good correlation with their pharmacological actions. It is concluded that CMSP may be used not only as a kind of packing material in bio-affinity chromatography, but also as a tool for studying the interactions between a drug and its receptor.     

Surface phase separation, dewetting feature size, and crystal morphology in thin films of polystyrene/poly(ε-caprolactone) blend

Thin films of polystyrene (PS)/poly(ε-caprolactone) (PCL) blends were prepared by spin-coating and characterized by tapping mode force microscopy (AFM). Effects of the relative concentration of PS in polymer solution on the surface phase separation and dewetting feature size of the blend films were systematically studied. Due to the coupling of phase separation, dewetting, and crystallization of the blend films with the evaporation of solvent during spin-coating, different size of PS islands decorated with various PCL crystal structures including spherulite-like, flat-on individual lamellae, and flat-on dendritic crystal were obtained in the blend films by changing the film composition. The average distance of PS islands was shown to increase with the relative concentration of PS in casting solution. For a given ratio of PS/PCL, the feature size of PS appeared to increase linearly with the square of PS concentration while the PCL concentration only determined the crystal morphology of the blend films with no influence on the upper PS domain features. This is explained in terms of vertical phase separation and spinodal dewetting of the PS rich layer from the underlying PCL rich layer, leading to the upper PS dewetting process and the underlying PCL crystalline process to be mutually independent.     

Polymer chain conformation in the phase separation process of a binary liquid mixture

A polymer chain conformation change near the critical point of liquid-liquid phase separation was investigated. Poly(N-isopropylacrylamide) labeled with a small amount of carbazolyl group for a fluorophore (P(NIPA-Cz)) was prepared. A ternary system of P(NIPA-Cz)+cyclohexane+methanol was investigated by the fluorescence spectroscopic technique. A mixed solvent of cyclohexane+methanol (CH/MeOH) shows phase separation at the upper critical solution temperature. Light scattering intensity, fluorescence emission intensity and fluorescence anisotropy ratio, as a function of temperature, were measured with quasi statically approaching to the critical demixing point. The fluorescence intensity of the carbazolyl groups attached to the polymer chain decreases with approaching to the critical temperature. This result suggests that the radius of gyration of the polymer decreases upon approaching to the critical demixing point of the solvent. We discuss the collapse and aggregation processes of the polymer based on the fluorescence quenching method. The rotational diffusion coefficient of carbazolyl groups attached to the polymer chain was estimated by the fluorescence depolarization technique. The rotational motion of carbazolyl groups is slowed down upon approaching the critical point.     

Modeling liquid-liquid interface level in a horizontal three-phase separator with a bucket and weir

The flow behavior in a three-phase separator with a bucket and weir was analyzed, and a theoretical equation for calculating the liquid-liquid interface level (H_H) in gravity separation zone was derived. The analysis indicates that the H_H increases as the flow rate and the density ratio of heavy to light liquid increase, and decreases linearly with increasing height difference between heavy and light liquid overflow weirs. The calculated H_H under different operating conditions is in good agreement with the experimental. With the proposed equation, the thicknesses of heavy and light liquid layers can be calculated, and then the minimum lengths of two phase layers required for separation can be determined separately. From the minimum lengths it can be clearly indicated that the governing step of liquid-liquid separation is in heavy or light liquid layers, hence the sizing of the separator can be optimized.