自组装短肽GFS-2构建新型三维细胞培养支架材料

典型的自组装短肽在水中可形成稳定的β-sheet二级结构,在生理性环境下则能够形成稳定的纳米纤维,可进一步形成含水量达99%的水凝胶,具有高纯度、可降解及无免疫反应等突出优点,能模拟生物体内的三维基质环境而作为细胞三维培养的新型生物材料。本文主要采用了圆二色谱仪、原子力显微镜、倒置显微镜等探究新型短肽GFS-2的自组装性能及其在细胞三维培养中的应用。此研究可能会启发设计更多的新型自组装短肽服务于化学、生物材料、医学工程等领域。     

由D型氨基酸设计自组装短肽D-EAK16构建新型三维纳米纤维支架材料

采用D型氨基酸设计自组装短肽D-EAK16, 运用圆二色仪及原子力显微镜等仪器和细胞三维培养, 发现短肽D-EAK16在30 ℃时具有稳定的二级结构β-sheet, 在一定浓度下D-EAK16可形成由纳米纤维构成的透明水凝胶, 含水量高达99％, 可在细胞培养基(如PBS, DMEM)中形成支架. 细胞三维培养显示, 该水凝胶对细胞HO-8910和SPC-A-1的生长未见毒性. 比较D型氨基酸纳米支架和L型氨基酸纳米支架, 细胞的毒性未发现显著性差异. 采用D型氨基酸构建的自组装短肽, 可提供一个三维基质培养系统, 期望能广泛应用于生物医学工程等领域.     

高分子修饰金纳米粒子的自组装研究进展

近年来,高分子修饰金纳米粒子的自组装行为逐渐成为新的研究热点.当金纳米粒子修饰上高分子后,在维持其自身光电特性的同时展现出了与高分子类似的自组装行为,从而能够在适当的条件下形成结构明确的零维、一维、二维和三维自组装结构.这些自组装结构的出现不仅促进了金纳米粒子组装的基础研究,并且极大地丰富了金纳米粒子的应用潜力,为金/高分子纳米复合材料的发展开拓了新的方向.本文总结了金/高分子纳米复合粒子形成的不同维度组装体,着重讨论了金纳米粒子自组装构筑单元的设计、组装方法以及组装体的性质,分类讨论了相应的自组装材料在环境和生物医药中的应用,并展望了相关研究在未来发展的机遇与挑战.     

界面可控硫醇SAMs纳米金修饰金电极的电化学行为研究

在裸金电极上自组装不同比例的4,4’-二甲基联苯硫醇(MTP)和硫辛酸(TA)混合液,形成自组装膜(MTP+TA/Au SAMs),再修饰纳米金,制得纳米金混合巯基修饰金电极(AuNPs/MTP+TA/Au)。研究了纳米金混合巯基修饰金电极的电化学行为和阻抗行为,结果表明电极表面pH值的改变对电极表面的电子转移有重要影响。对葡萄糖传感器的制备条件、测定条件、抗干扰能力等进行了讨论,结果表明修饰电极的微结构和微环境有必要进一步研究。     

Study on Electrochemical Behavior of Controllable Interface Alkanethiols Selfassembled Monolayers and Au Nanoparticles Modified Gold Electrode

在裸金电极上自组装不同比例的4,4’-二甲基联苯硫醇(MTP)和硫辛酸(TA)混合液,形成自组装膜( MTP+ TA/Au SAMs),再修饰纳米金,制得纳米金混合巯基修饰金电极(AuNPs/MTP+ TA/Au).研究了纳米金混合巯基修饰金电极的电化学行为和阻抗行为,结果表明电极表面pH值的改变对电极表面的电子转移有重要影响.对葡萄糖传感器的制备条件、测定条件、抗干扰能力等进行了讨论,结果表明修饰电极的微结构和微环境有必要进一步研究.     

基于微机电系统技术和纳米金自组装膜的安培型免疫传感器研究

基于微机电系统(MEMS)技术制备安培型免疫传感器,并利用基于硫醇单层膜的纳米金单层膜自组装技术设计传感器界面,用于固定人免疫球蛋白(IgG)抗体,研制了一种新型的安培型免疫传感器。采用MEMS技术,在硅片上制备微型的三电极系统以及SU-8反应池。基于自组装技术,先在金电极上自组装巯基乙胺单层膜,利用膜上氨基与纳米金共价结合组装纳米金单层膜,得到可用于固定抗体的界面。实验探讨了影响抗体固定的主要实验参数和条件;考察了采用此固定化方法传感器的响应性能,与金电极直接吸附固定法和戊二醛共价交联固定法进行了比较。对IgG检测的实验结果表明,采用纳米金自组装膜固定抗体,具有活性高、非特异性吸附小、检测线性范围宽等优点。并且,基于MEMS技术的安培型免疫传感器具有微型化、与集成电路工艺相兼容、易于实现传感器的阵列化和实时多参数检测等优点。     

硅基底金纳米粒子微阵列电极的制备及其电化学性质的研究— 多孔硅电致发光 生物传感器研究的前期探索

用Frens法制备了不同粒径的金纳米粒子,并用透射电镜、紫外可见分光光度法进行了表征。用自组装技术得到了金膜电极表面的金纳米粒子二维阵列电极,用扫描电镜、电化学等方法对该微阵列电极进行了表征。结果表明,当金电极表面被自组装膜完全覆盖后,电化学反应不再发生,而将金纳米粒子组装到膜上以膈,才得到电化学信号。我们认为,金纳米粒子在这里对电荷的跨膜转移有很强的促进作用。对于该过程的研究,用助于理解电荷的转移机制,对进一步理解电荷隧穿过程有一定的指导意义。     

表面活性剂类多肽A6KA6K的自组装及机理研究

为了研究表面活性剂类多肽疏水链段长度及亲疏水氨基酸比例对其自组装结构的影响,本文设计了一种表面活性剂类多肽A6K的二倍体A6KA6K。圆二色谱分析表明的二级结构主要为无规卷曲结构并伴有少量的α-螺旋;透射电子显微镜和动态光散射分析表明,其在水溶液中能自组装形成纳米囊泡状结构。芘荧光分子探针研究表明自组装体存在疏水微区域将芘分子包裹在其中,证明了这种多肽在溶液中可形成胶束类的自组装体,并计算了其临界胶束浓度。相比已报道的表面活性剂类肽A6K,本文设计的肽序列A6KA6K由于在较长疏水链段区域中存在亲水性氨基酸K,对疏水相互作用有影响,使得含有14个氨基酸的肽自组装形成纳米囊泡状结构。     

巯基修饰单链DNA在纳米金薄膜电极上自组装、杂交和取向的电化学交流阻抗谱

利用电化学交流阻抗技术对SH-ssDNA在纳米金薄膜电极表面的自组装、杂交和取向进行了系统表征。 探讨了SH-ssDNA的组装时间、浓度和链长对其自组装的影响,自组装15 h时电荷传递电阻Rct最大,表面覆盖率最高;研究了SH-ssDNA的浓度、链长以及与互补DNA的杂交方式对杂交反应的影响。 结果发现,随着单链浓度的增加,杂交后R_ct的变化值逐渐降低,当SH-ssDNA为5 μmol/L时Rct值比杂交前增加了16%。 通过对阻抗谱数据模拟和分析,表明SH-ssDNA以垂直竖立取向在金电极表面形成均匀致密单分子层,杂交效率与SH-ssDNA的覆盖率密切相关。     

纳米金-4,4'-二巯基二苯硫醚自组装膜修饰金电极的制备及其电化学行为

纳米金粒子,因其良好的光学、电学特性和生物相容性,受到分析化学工作者的极大关注.本研究利用4,4'-二巯基二苯硫醚(DMDPSE)中两端巯基的S原子与Au表面强烈作用形成Au-S键,构筑了纳米金-4,4'-二巯基二苯硫醚自组装膜修饰金电极(NG/DMDPSE/Au),然后研究了该电极的电化学行为.这不仅对纳米材料构建在基质表面提供了一个有效途径,而且对纳米粒子制成具有特殊功能的生物传感器具有一定的参考价值.     

Designing peptide based nanomaterials

This tutorial review looks at the design rules that allow peptides to be exploited as building blocks for the assembly of nanomaterials. These design rules are either derived by copying nature (alpha-helix, beta-sheet) or may exploit entirely new designs based on peptide derivatives (peptide amphiphiles, pi-stacking systems). We will examine the features that can be introduced to allow self-assembly to be controlled and directed by application of an externally applied stimulus, such as pH, light or enzyme action. Lastly the applications of designed self-assembly peptide systems in biotechnology (3D cell culture, biosensing) and technology (nanoelectronics, templating) will be examined.     

Catch and release cell sorting: electrochemical desorption of T-cells from antibody-modified microelectrodes

The development of integrated microsystems capable of interrogation, characterization and sorting of mammalian cells is highly significant for further advancement of point-of-care diagnostics and drug discovery fields. The present study sought to design a novel strategy for releasing antibody-bound cells through electrochemical disruption of the underlying antibody (Ab) layer. A microsystem for selective capture and release of cells consisted of an array of individually addressable gold microelectrodes fabricated on a glass substrate. Poly(ethylene glycol) (PEG) hydrogel photolithography was employed to make the glass regions non-fouling, thus, ensuring selective localization of proteins and cells on the microelectrodes. The gold surfaces were decorated with anti-CD4 Ab molecules using standard alkanethiol self-assembly and carbodiimide coupling approaches. The Ab-functionalized electrodes selectively captured model T-lymphocytes (Molt-3 cells) expressing CD4 antigen while minimal cell adhesion was observed on PEG hydrogel-modified glass substrates. Importantly, application of a reductive potential (-1.2V vs. Ag/AgCl reference electrode) resulted in release of surface-bound T-cells from the electrode surface. Cyclic voltammetry and fluorescence microscopy were employed to verify that the detachment of captured T-cells was indeed due to the electrochemical disruption of the underlying alkanethiol-Ab layer. In the future, the cell sorting approach described here may be combined with microfluidic delivery to enable Ab-mediated capture of T-lymphocytes or other cell types followed by release of select cells for downstream gene expression studies or re-cultivation.     

甲烷氧化菌素功能化金纳米层层自组装修饰电极上过氧化氢的催化还原

借助巯基试剂,在纳米金颗粒表面修饰生物活性物质Mb,制备保持有Mb生物活性的功能化金纳米巯基乙胺-Au NPs-Mb.采用UV-Vis、FTIR光谱和投射电镜表征其结构,该纳米颗粒分布均匀且粒径均一,并显著改善了金纳米颗粒团聚现象.以Mb功能化金纳米为基元,采用单层自组装及层层自组装方式将其修饰到裸金电极表面.各Mb或Mb-Cu电极的电化学测试并未借助电子传递媒介.配位Cu~(2+)后,修饰有Mb的单层及层层自组装修饰的催化还原能力均显著提升.其中Cu~(2+)配位的{巯基乙胺-Au NPs-Mb}3/Au修饰电极作为一种新型H2O2生物传感器,响应时间大约为2 s,米氏常数KappM为0.787 mmol/L,表现出了较强的还原H2O2的催化活性,且稳定性较好.     

细胞色素c在纳米杂化膜修饰玻碳电极上的直接电化学

以多壁碳纳米管(MWNTs)修饰玻碳(GC)电极为基底,自组装金纳米粒子(AuNPs)及L-半胱氨酸(L-Cys)研制杂化膜修饰电极(L-Cys/AuNPs/MWNTs/GC).实验表明,该膜修饰电极在pH=7.0的KH2PO4-K2HPO4缓冲溶液中对细胞色素c(Cyt c)的直接电子转移反应具有良好的电催化作用,C...     

Assembly process of CuHCF/MPA multilayers on gold nanoparticles modified electrode and characterization by electrochemical SPR

Gold nanoparticles were deposited onto 2-mercaptoethylamine (MEA)-assembled planar gold thin film to construct gold nanoparticles modified electrode by virtue of a solution-based self-assembly strategy. Subsequently, 3-mercaptopropionic acid (MPA)-bridged copper hexacyanoferrate (CuHCF) multilayers were constructed on the as-prepared gold nanoparticles modified electrode. The resulted multilayer nanostructures were investigated by electrochemical surface plasmon resonance (EC-SPR) and atomic force microscopy (AFM) with primary emphasis upon the effect of the gold nanoparticles on the MPA/CuHCF multilayers growth and their surface morphology. Compared with the multilayer system on a planar gold electrode, the different electrochemical and optical properties might result from higher curvature effect and extraordinary surface-to-volume ratio characteristic of gold nanoparticles and the nanoparticle-selective growth of CuHCF. A dendrimer-like assembly process was proposed to explain the experiment results. This new motif of multilayer on the gold nanoparticles modified electrode was different from that of on a planar gold electrode, indicating a potential application of EC-SPR technique in the study of nanocomposite materials.     

电化学石英晶体微天平实时表征和定量检测短序列DNA

利用电化学石英晶体微天平(EQCM)这一灵敏的质量和电化学传感器测定特定序列DNA。应用自组装膜技术在压电石英晶振表面自组装一带羧基的α－硫辛酸单层膜,通过盐酸1-乙基-3-(3-二甲基氨基丙基)碳二亚胺(EDC)及N-羟基琥珀酰亚胺(NHS)共价固化寡聚核苷酸为探针,用于测定与其碱基序列互补的DNA。实验中EQCM实时监测了α-硫辛酸的自组装过程、探针固化过程及其与cDNA杂交过程。定量得出了探针固化量及cDNA杂交量。在酸性、中性和碱性条件下,分别对固化和杂交过程进行表征,实验发现探针固化及DNA杂交都受pH影响,本文对此现象进行了解释。同时,利用染料Hoechst33258的电化学活性,使其与双链DNA嵌合,通过测量Hoechst33258的电化学信息进一步验证了DNA杂交关键步骤。     

含蜜胺基团的新型苝酰亚胺染料的合成及纳米纤维的构筑

合成了一种含三嗪基团的新型苝酰亚胺染料(T-PTCD), 并对其分子结构进行了确认. 考察了溶剂的极性和溶剂体积比等因素对相转移法和快速溶剂扩散法制备的T-PTCD聚集体形貌结构的影响. 结果表明, 以甲醇和三氯甲烷分别作为"不良"溶剂和"良"溶剂, 低体积比甲醇/氯仿在一定程度上有利纳米纤维的形成; 当体积比为1:4时, 采用相转移法可制备出直径大约100 nm左右, 长度为几十微米的结构规整的纳米纤维.     

Comparative studies on electrogenerated chemiluminescence of luminol on gold nanoparticle modified electrodes

Comparative studies on the electrogenerated chemiluminescence (ECL) behavior of luminol on various electrodes modified with gold nanoparticles of different size were carried out in neutral solution by conventional cyclic voltammetry (CV). The results demonstrated that the gold nanoparticle modified electrodes could generate strong luminol ECL in neutral pH conditions. The catalytic performance of gold nanoparticle modified electrodes on luminol ECL depended not only on the gold nanoparticles but also on the substrate. Gold electrode and glassy carbon electrode were the most suitable substrates for the self-assembly of gold nanoparticles. Moreover, the gold nanoparticle modified gold and glassy carbon electrode had satisfying stability and reproducibility and did not need tedious pretreatment of electrode surface before each measurement. It was also found that luminol ECL behavior depended on the size of gold nanoparticles. The most intense ECL signals were obtained on a 16-nm-diameter gold nanoparticle modified electrode. The modified electrode prepared by the self-assembly method exhibited much better catalytic effect on luminol ECL than that prepared by the electrically deposited method. The ECL behavior of luminol on a gold nanoparticle self-assembled gold electrode was also investigated by other transient-state electrochemical techniques, such as chronoamperometry, differential pulse voltammetry, normal pulse voltammetry, and square wave voltammetry. The strongest ECL intensity was obtained under square wave voltammetric condition.     

短杆菌肽在十八烷基硫醇自组装单层膜上的通道行为

短杆菌肽是短杆芽孢菌在芽孢形成过程中合成的一组憎水十五肽,它能在脂双层膜上形成一价阳离子通道,允许一些一价阳离子通过．短杆菌肽离子通道研究在天然双层膜以及人工双层膜,如类脂双层膜（BLM）、脂质体上开展的较多,而基于支撑膜的研究则极少［1-4]．本文在金电极上制备硫醇自组装单层膜,研究了短杆菌肽的离子通道行为,并提出了可能的机理．