Two-dimensional auto-organized nanostructure of sodium hyaluronate and its frictional properties

The two-dimensional auto-organized nanostructure of sodium hyaluronate NaHA on bovine serum albumin BSA monolayer was studied by a layer-by-layer method. The surface properties were studied by a quartz crystal microbalance QCM method and by using an atomic force microscope AFM. NaHA showed a Langmuir-type adsorption and was found to form honeycomb-like networks. With increasing adsorption amount of NaHA, their mesh size decreased and their strand size increased in width. The surface nanomechanical properties, such as adhesion force F_ad and frictional forces F_f between the surfaces of the NaHA layers and the AFM tip, were studied in air and in NaHA solutions using a contact mode and a lateral force modulation LFM of AFM. The values of F_ad and F_f obtained in air were found to be higher than those obtained in the solutions because of the effect of moisture film on the NaHA layers. The values of F_ad and frictional coefficients in the solutions increased with increasing .     

Surface structures of adsorption layers of sodium hyaluronate and bovine serum albumin complexes on poly(γ-methyl-l-glutamate) film and their surface properties

Two-dimensional structures and characteristics of the complexes between sodium hyaluronate (NaHA) and bovine serum albumin (BSA) were studied by using a quartz crystal microbalance method and an atomic force microscope (AFM). NaHA did not adsorb on poly(-methyl-l-glutamate) (PMLG) film. On the other hand, the complexes adsorbed on it and the adsorption behaviors were found to be Langmuir types. With increasing weight ratio of BSA to NaHA, W _BSA, the adsorption constants K decreased and the saturated adsorption masses increased. The adsorbed complexes were spherical particles and at saturated adsorption states they covered compactly on the PMLG film. The mean diameters d _AFM estimated from the topographic images decreased from 70 to 54 nm with increasing W _BSA. The adhesion force F _ad and the frictional force F _f between the complex layers and the AFM tip were obtained by using the contact mode of the AFM. With increasing W _BSA, the values of F _ad decreased and the values of F _f increased. Compared with the frictional coefficient of the NaHA adsorption layer on the BSA monolayer, the values for the NaHA–BSA complex layer were found to be much higher.     

含氰基聚合物微球对铜离子吸附性能的研究

以火焰原子吸收光谱法(FAAS)为检测手段,研究了聚丙烯腈微球(PANMS)对溶液中Cu2+的吸附及其影响因素,并建立了PANMS分离富集-FAAS法。实验结果表明,溶液pH为5、静态吸附时间为1.5 h、温度为20℃时,其对Cu2+的吸附达到饱和而稳定,吸附容量为30.2 mg/g,吸附率可达到87.5%。随着吸附时间的延长吸附率有所提高,但幅度不是很大。以0.1 mol/LHC l溶液作为解吸剂,解吸率可达到96.5%。经富集50倍后,测Cu2+工作曲线的回归方程为A=0.0025C(μg/L)-0.0026(r=0.9993),方法的检出限为1.68μg/L,相对标准偏差(RSD)小于2.9%。加标回收率为91.4%~97.0%。     

Nanoscale mechanical property of marine and continental organic kerogen in shale

Kerogen is known as an important organic part for absorbing and forming shale gas whose absorption function,especially mechanical and tribological properties,has not been fully revealed.Here,we use Fourier transform infrared(FTIR) and X-ray photoelectron spectroscopy(XPS) analysis to reveal the chemical structure of kerogen.We report the first study of the adhesion and friction behavior of kerogen using atomic force microscope(AFM) Nanoman technology.Our finding reveals the friction of kerogen is decreased at higher pressure while is inhibited at increased temperature,and friction decreases logarithmically as the sliding speed increases.The weakened of Al-O linkage at high temperature have great influence on the decrease of friction forces between kerogen and alumina pellet.This finding lays the mechanism for understanding the dynamic adhesion behavior of kerogen in frictions,therefore attracting increasing interests from scientists,researchers,petroleum engineers and investors.     

基于原子力显微镜研究农药对溶菌酶淀粉样纤维化过程的影响

本文利用原子力显微镜(AFM)在分子水平上研究了三氯杀螨醇、氟氯氰菊酯、三唑酮和西维因四种农药对淀粉样纤维化过程的影响。结果发现,四种农药对溶菌酶淀粉样纤维的形貌特征均没有明显的影响。但是,三氯杀螨醇和氟氯氰菊酯缩短了淀粉样纤维生长的指数生长期,对溶菌酶淀粉样纤维化过程有促进作用,而三唑酮和西维因对纤维化过程没有明显的影响。结合表面等离子体共振技术和荧光光谱技术的分析结果,可以推测三氯杀螨醇和氟氯氰菊酯与溶菌酶结合后,使蛋白质构象发生变化而促进了淀粉样纤维的形成。本文不仅从分子水平上研究农药与淀粉样纤维化过程的关系,还有望为预防淀粉样变性疾病提供理论参考。     

荷叶表面纳米结构与浸润性的关系

通过烘烤、化学萃取及物理剥除等方法改变荷叶表面的纳米结构和化学组成, 在环境扫描电镜(ESEM)和全反射红外光谱(ATR)对样品的微观形貌和化学组成进行表征的基础上, 为消除其它外界因素影响样品的真实微观形貌, 进一步采用原子力显微镜(AFM)进行了表征. 通过测量不同处理方法所得样品的表观接触角表征了样品的浸润性质. 结果表明, 荷叶表面的蜡质是产生表面疏水性的根本原因, 其微米级结构放大了其疏水性, 而纳米结构是导致其表面高接触角、低滚动角, 即“荷叶效应”的关键原因.     

Two-dimensional scaffold layer formations on a solid surface through xanthan polysaccharide: Temperature effect

The influences of temperature on xanthan biopolymer assemblies on a two-dimensional surface have been thoroughly studied. High resolution atomic force microscope images show that the xanthan nanofibrils can be used to build up well-dispersed 2D scaffold layer after 1 day annealing at 35 °C. By increasing annealing temperatures (60 °C, 90 °C) of xanthan solutions, the well-dispersed layers can be produced rapidly (6 h, 0.5 h) with micro-sized pore structures. The xanthan scaffold with pore structures potentially allows accommodating micro-sized cells for tissue engineering.     

铅离子印迹固相萃取原子吸收光谱分析

以Pb2+为模板,丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,采用本体聚合技术,制备了对Pb2+具有特异性识别作用的离子印迹材料。通过红外光谱,吸附容量,干扰实验等讨论了该离子印迹材料的相关性质。结果表明,该离子印迹材料对Pb2+的结合能力明显强于非印迹材料,能够很好的排除其他金属离子的干扰。通过制备该离子印迹材料,能够富集水体中的痕量铅,结合原子吸收光谱法对其进行定量分析,为测定复杂环境样品中痕量铅离子提供一个高选择性,高预富集效率的固相萃取材料和分析方法。     

二氧化硅胶体晶体组装形貌研究

用原子力显微镜表征了二氧化硅胶体晶体的组装,探讨了二氧化硅微球用自然沉降法、抽滤法、溶剂挥发法组装时的组装行为,同时讨论了不同颗粒表面电位、不同溶剂介质及不同温度对其组装结果的影响。结果表明,颗粒表面电位是影响二氧化硅胶体晶体有序组装的重要因素之一。文中总结了最优的介质组成和温度条件,指出溶剂挥发法是较优的二氧化硅胶体晶体组装方法,其方法操作简单、周期短、得到的胶态晶体质量高,能在较大面积内高度有序。     

Direct measurement of hydrophobic particle–bubble interactions in aqueous solutions by atomic force microscopy: Effect of particle hydrophobicity

Direct measurements of the interaction forces between a spherical silica particle and a small air bubble have been conducted in aqueous electrolyte solutions by using an atomic force microscope (AFM). The silica particle was hydrophobized with a silanating reagent, and the interaction forces were measured by using several particles with different surface hydrophobicities. In the measured force curves, a repulsive force was observed at large separation distances as the particle moved towards the bubble. The origin of the repulsive force was attributed to an electrostatic double-layer force because both the particle and bubble were negatively charged. After the repulsive force, an extremely long-range attractive force acted between the surfaces. These results indicate that the intervening thin water film between the particle and bubble rapidly collapsed, resulting in the particle penetrating the bubble.

The instability of the thin water film between the surfaces suggests the existence of an additional attractive force. By comparing the repulsive forces of the obtained force curves with the DLVO theory, the rupture thickness was estimated. The hydrophobicity of the particle did not significantly change the rupture thickness, whereas the pH of the solution is considered to be a critical factor.     

Fabrication of macroporous polystyrene/graphene oxide composite monolith and its adsorption property for tetracycline

Macroporous polystyrene microsphere/graphene oxide(PS/GO) composite monolith was first prepared using Pickering emulsion droplets as the soft template. The Pickering emulsion was stabilized by PS/GO composite particles in-situ formed in an acidic water phase. With the evaporation of water and the oil phase(octane), the Pickering emulsion droplets agglomerated and combined with each other, forming a three-dimensional macroporous PS/GO composite matrix with excellent mechanical strength. The size of the macrospores ranged from 4 mm to 20 mm. The macroporous PS/GO composite monolith exhibited high adsorption capacity for tetracycline(TC) in an aqueous solution at p H 4–6. The maximum adsorption capacity reached 197.9 mg g 1at p H 6. The adsorption behaviour of TC fitted well with the Langmuir model and pseudo-second-order kinetic model. This work offers a simple and efficient approach to fabricate macroporous GO-based monolith with high strength and adsorption ability for organic pollutants.     

磁性水铁矿的制备及其对二甲基亚胂酸的吸附性能

二甲基亚胂酸会对人体和环境造成严重危害。用水热法合成磁性水铁矿,对产物进行了X射线衍射分析、BET比表面积分析和磁滞回线分析,结果表明磁性水铁矿纯度较高,比表面积较大,具有较强的磁性。用磁性水铁矿作为吸附剂,考察了二甲基亚胂酸在磁性水铁矿上的吸附动力学及吸附等温线。二甲基亚胂酸在磁性水铁矿上的吸附符合准二级动力学模型,吸附速率为0.34g·mg^-1·h^-1;吸附等温线符合Freundlich模型。采用Zeta电位测定、FT-IR、SEM-EDS和XPS对吸附机理进行分析,表明磁性水铁矿通过配位络合作用和静电作用来吸附二甲基亚胂酸,在吸附过程中磁性水铁矿表面形了成Fe-O-As三元络合物。研究结果为含有二甲基亚胂酸污染物的水体处理和净化提供了新方法。     

硅烷化和多聚赖氨酸化衬底结合容量的比较

微流控芯片和生物芯片因其筛选高通量、体积微型化和便携化、功能集成化、分析快速等特点,在生物学研究中得到广泛的应用,促进了基因组学[1]和蛋白质组学[2]的研究。衬底的修饰是生物芯片制备工序中一道重要的环节,对保持生物样品的活性、提高生物样品的有效结合率起着非常重要     

Separation of flavonoid and alkaloid using collagen fiber adsorbent

Flavonoids and alkaloids are two major classes of plant compounds with biological activities, and they usually coexist in many medicinal herbs. In this study, a novel collagen fiber adsorbent (CFA) was prepared, and its application for adsorption chromatography separation of flavonoids and alkaloids was systematically investigated. The typical flavonoids, rutin and baicalin, and the typical alkaloids, matrine and caffeine, were selected as probe molecules for the investigations. The batch adsorption behaviors of these compounds on CFA in different solvents indicated that hydrogen bond plays a predominant role for the adsorption of flavonoid and alkaloid in pure ethanol, while the hydrophobic interaction plays a predominant role for the adsorption in water. In column chromatography separation, flavonoids were completely separated from alkaloids by a stepwise elution process with pure ethanol followed by aqueous ethanol solution. The two flavonoids, rutin and baicalin, were also well separated although the two alkaloids, matrine and caffeine, were washed out together. The optimal loading volume of sample solution (10 mg/mL) for the separation was determined as 0.66 mL/g CFA. Under these conditions, flavonoid and alkaloid were effectively separated with a recovery higher than 90% in 8 times repeated applications.     

纳米级钡铁氧体的原子力显微镜分析及微波性能的研究

采用溶胶-凝胶法制备掺杂钡离子的纳米六角晶型铁氧体.采用X衍射仪对其物相进行鉴定,利用原子力显微镜对不同方法制得的试样粒径进行了分析研究,最后用网络分析仪对铁氧体在1～6 GHz范围内的微波性能进行分析,结果表明:实验制得粉体为M型钡铁氧体,利用乙醇分散的稀浓度的试样能在原子力显微镜下很好地观察到颗粒的粒径,其平均粒径为52.68 nm左右,并且实验制得的纳米M型钡铁氧体具有较大的介电损耗和磁损耗,具有良好的吸波性能.     

基于金纳米粒子掩模的硅表面纳米结构加工

利用金溶胶纳米粒子为掩模,结合轻敲模式原子力显微镜（TM AFM）的局域氧化技术和化学湿法腐蚀,对Si表面进行纳米尺度的结构加工,得到柱状和环状纳米结构.实验结果表明,氧化过程中AFM针尖与样品平均间距的大小显著影响后续纳米结构的形状.保持一定的氧化偏压、扫描速度和相对湿度,当针尖与样品间距为7.5 nm时,可得到柱状纳米结构;而当间距减小到5 nm时,则得到带芯环状纳米结构.不同几何形状的纳米结构形成的原因是体系中纳米粒子物理屏蔽效应.     

Kinetics of phosphate adsorption on goethite: comparing batch adsorption and ATR-IR measurements

The adsorption kinetics of phosphate on goethite has been studied by batch adsorption experiments and by in situ ATR-IR spectroscopy at different pH, initial phosphate concentrations and stirring rates. Batch adsorption results are very similar to those reported by several authors, and show a rather fast initial adsorption taking place in a few minutes followed by a slower process taking place in days or weeks. The adsorption kinetics could be also monitored by integrating the phosphate signals obtained in ATR-IR experiments, and a very good agreement between both techniques was found. At pH 4.5 two surface complexes, the bidentate nonprotonated (FeO)(2)PO(2) and the bidentate protonated (FeO)(2)(OH)PO complexes, are formed at the surface. There are small changes in the relative concentrations of these species as the reaction proceeds, and they seem to evolve in time rather independently. At pH 7.5 and 9 the dominating surface species is (FeO)(2)PO(2), which is accompanied by an extra unidentified species at low concentration. They also seem to evolve independently as the reaction proceeds. The results are consistent with a mechanism that involve a fast adsorption followed by a slow diffusion into pores, and are not consistent with surface precipitation of iron phosphate.     

扫描探针显微术在巯醇自组装单分子膜纳米刻蚀中的应用

介绍了近十年来扫描探针显微术(SPM)在巯醇自组装单分子膜纳米刻蚀中的应用. 依据扫描探针的工作原理, 依次讨论了扫描隧道显微镜、原子力显微镜和导电原子力显微镜的工作特点和适用范围. 同时也讨论了自组装单分子膜纳米刻蚀术在生物分子传感器、超高密度信息存储等领域的应用前景.     

Single-Molecule Force Spectroscopy of DNA-Based Reversible Polymer Bridges: Surface Robustness and Homogeneity

Single-molecule force spectroscopy, as implemented in an atomic force microscope, provides a rarely used method by which to monitor dynamic processes that occur near surfaces. Here, a methodology is presented and characterized that facilitates the study of polymer bridging across nanometer-sized gaps. The model system employed is that of DNA-based reversible polymers, and an automated procedure is introduced that allows the AFM tip–surface contact point to be automatically determined, and the distance d between opposing surfaces to be actively controlled. Using this methodology, the importance of several experimental parameters was systematically studied, e.g. the frequency of repeated tip/surface contacts, the area of the substrate surface sampled by the AFM, and the use of multiple AFM tips and substrates. Experiments revealed the surfaces to be robust throughout pulling experiments, so that multiple touches and pulls could be carried out on a single spot with no measurable affect on the results. Differences in observed bridging probabilities were observed, both on different spots on the same surface and, more dramatically, from one day to another. Data normalization via a reference measurement allows data from multiple days to be directly compared.     

Multicomponent membranes on solid substrates: Interfaces for protein binding

Even though lipid membranes deposited on a solid support are now used for more than 20 years as a model system for cellular membranes, their potential has, as yet, not been fully exploited. Only in recent years, the composition of solid supported membranes became more and more complex, which is a prerequisite for the elucidation of biologically relevant protein adsorption processes. Multicomponent bilayers resemble the heterogeneity of the biological membrane, which is composed of hundreds of different lipids varying in their headgroup and acyl chain composition. The development of a multitude of elaborated surface sensitive techniques allows to study the phase behavior of these membranes and their interaction with proteins, some of which will be highlighted in this review.