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1.
郑国祥  邵勇  徐斌 《化学学报》2006,64(8):733-737
用苯胺作还原剂还原氯金酸合成了金纳米结构. TEM实验表明, 苯胺还原氯金酸能生成苯胺齐聚物或其聚合物包裹的金球形纳米粒子. XPS分析表明, 金纳米粒子包覆的聚合物层带正电荷. 该纳米粒子能用于电极表面纳米结构组装及氧化还原性的生物大分子的电化学研究, 实现了超氧化物歧化酶(SOD)在这种带正电荷的金纳米粒子表面的直接电子转移.  相似文献   

2.
细胞吞噬表面电荷不同的硅纳米颗粒的研究   总被引:2,自引:0,他引:2  
本文以HepG细胞、L-02细胞和MCF-7细胞为代表, 利用异硫氰酸罗丹明荧光SiNPs的荧光信号同步指示作用, 研究了细胞对表面带正电荷的氨基化SiO2荧光纳米颗粒(PSiNPs)和表面带负电荷的SiO2荧光纳米颗粒(NSiNPs)的吞噬情况, 并考察了SiNPs浓度、培育时间及培养基中的血清对细胞吞噬表面电荷不同的SiNPs颗粒的影响.  相似文献   

3.
采用表面活性剂3-氨丙基三乙氧基硅烷(APTES)修饰Fe3O4磁性纳米粒子, 经质子化后, Fe3O4磁性纳米粒子表面披覆大量的正电荷, 与表面带负电荷的巯基丙酸(MPA)修饰的核壳CdSe/CdS/ZnS量子点(QDs)通过强烈的静电作用而发生组装, 得到兼具磁性和荧光性能的磁性荧光纳米材料. 利用透射电子显微镜(TEM)、傅里叶变换红外光谱仪(FTIR)、X射线衍射仪(XRD)、荧光分光光度计和振动样品磁强计(VSM)等测试手段对磁性荧光纳米材料进行表征. 研究表明, 由两种粒子组装的核壳结构复合粒子拥有良好的磁性能和荧光性能.  相似文献   

4.
用固相合成法制备阳离子氨基酸组成的多肽,再将其连接到巯基化合物上,用于纳米金表面配体交换,制备阳离子多肽修饰的纳米金,并研究了这种纳米粒子对油-水(O/W)乳液界面酶促反应速度的影响.结果发现,将含有荧光底物的乳滴同酶直接混合时,45 min内溶液中未检测到荧光信号变化,但向该溶液中加入纳米粒子后溶液中荧光信号立即增强.出现该现象的主要原因是,当乳液界面酶促反应体系中含有纳米粒子时,纳米粒子表面的阳离子多肽同时吸附带负电荷的酶和乳液,迅速屏蔽酶与乳液之间的电荷排斥,使酶与乳液中的底物能有效接触,加速酶促反应进行;通过选用不同的油相制备乳液,调控纳米粒子与乳液之间的氢键作用,还可使酶促反应速度进一步提高.  相似文献   

5.
建立了一种基于金纳米粒子与巯基相互作用的在磁性高分子复合微球表面高效组装功能分子的新方法.首先制备了粒径均一的介孔磁性纳米粒子簇(MSP),利用蒸馏沉淀技术在MSP上包覆一层―S―S―键交联的聚甲基丙烯酸壳层(P(MAA-Cy)),并将直径10~30 nm的金纳米粒子沉积在MSP@P(MAACy)复合微球表面,从而获得MSP@P(MAA-Cy)-Au NP复合微球.调控HAu Cl4的投料量可以控制金纳米粒子沉积数量和尺寸.利用金粒子和巯基之间的强相互作用,将巯基修饰的荧光分子快速可控组装在MSP@P(MAA-Cy)-Au NP微球上.作为模型示范,实现了一次在MSP@P(MAA-Cy)-Au NP微球上快速固定单种或多种功能分子,为即时、高效、定量在功能微球(靶向药物载体等)上修饰功能分子提供了一种可选择的解决方案.  相似文献   

6.
吴超  郭红燕  胡家文 《化学学报》2009,67(14):1621-1625
研究了α-甲氧基-ω-巯基聚乙二醇(mPEG-SH, 5000 MW)修饰的金溶胶的稳定性, 初步探讨了其稳定机制. 将线性mPEG-SH通过巯基化学吸附于金溶胶表面, 可形成高分子层包被的金溶胶. 研究结果表明, PEG修饰的金溶胶可以在pH=1~13.5或盐浓度高达1.20 mol/L的较苛性条件下保持稳定. 这是由于金溶胶表面吸附的高分子保护层为溶胶提供了新的空间稳定, 取代了溶胶原来的DLVO稳定(实质是电荷稳定). 因而, PEG保护的金溶胶在很大程度上克服了DLVO稳定的溶胶对环境敏感、易聚沉的缺点, 能在复杂的条件(如生理条件)下应用. 鉴于PEG的水溶性、无毒性和生物亲和性, 这种具有较高稳定能力的金纳米粒子/PEG复合体结合了金纳米粒子和PEG的优异性能, 可作为生物纳米探针用于复杂条件下的生物分析.  相似文献   

7.
以表面接枝聚乙二醇链的聚酰胺胺树枝状聚合物(PEG-PAMAM)为纳米载体, 在其内部空腔包覆金纳米粒子, 在金纳米粒子表面连接硫辛酸改性的阿霉素(LA-DOX), 从而间接实现了抗癌药物在PEG-PAMAM内的高效负载. 同时, LA-DOX中的酰腙键提供pH响应性, 实现了药物的pH响应性释放. 紫外-可见(UV-Vis)光谱表明, 包覆金纳米粒子的PEG-PAMAM纳米载体对LA-DOX的负载能力显著增强. 体外细胞实验表明, 负载LA-DOX的树枝状聚合物-金纳米粒子复合药物载体具有较强的抗肿瘤能力.  相似文献   

8.
姜炜  黄蕾  张玉忠 《分析化学》2011,39(7):1038-1042
构建了基于金纳米粒子/聚阿魏酸/多壁碳纳米管(AuNPs/PFA/MWCNTs)修饰电极的DNA计时库仑法生物传感器.利用循环伏安技术在多壁碳管修饰的玻碳电极表面上聚合一层阿魏酸,在恒电位条件下,在阿魏酸表面沉积金纳米粒子,巯基DNA作为探针通过金硫键固定在金纳米粒子表面.电化学交流阻抗技术(EIS)与扫描电镜(SEM...  相似文献   

9.
张大峰  刁鹏  刘鹏  王静懿  项民  张琦 《化学学报》2007,65(21):2370-2376
研究了组装在Au, Pt电极表面的金纳米粒子对CO的电化学催化氧化行为, 首次在实验上观察到较大粒径金纳米粒子(粒径>10 nm)对CO的电催化氧化活性. 考察了金粒子表面金氧化物对粒子电催化活性的影响, 发现表面金氧化物的形成是金纳米粒子对CO具有电催化氧化活性的前提. 对于相同粒径的金纳米粒子, 随着粒子表面金氧化物量的增加,催化活性增大.  相似文献   

10.
以转铁蛋白溶液为外水相,聚乳酸丙酮溶液为油相,纳米沉淀法制备了表面结合转铁蛋白的聚乳酸纳米微粒,以二氯亚锡为还原剂,直接法和CDPTA螯合法对纳米微粒进行99mTc放射性标记,以C6胶质瘤细胞实验考察了标记对纳米微粒表面转铁蛋白活性的影响,结果表明直接法标记率较高,大于80.1%,对转铁蛋白活性有影响。CDPTA螯合法标记法较低(72.3%),对转铁蛋白活性影响较小。以脑部荷胶质瘤大鼠为动物模型,鼠尾静脉注射放射性标记纳米微粒,SPECT示踪和γ计数器检测显示:以转铁蛋白表面修饰的聚乳酸纳米微粒经静脉注射后主要分布于肝、脾,与正常鼠相比,荷胶质瘤大鼠对纳米微粒的摄取率有所提高。  相似文献   

11.
It is well known that the electrostatic repulsions between charges on neighboring sites decrease the effective charge at the surface of a charged nanoparticle (NP). However, the situation is more complex close to a dielectric discontinuity, since charged sites are interacting not only with their neighbors but also with their own image charges and the image charges of all neighbors. Titrating site positions, solution ionic concentration, dielectric discontinuity effects, and surface charge variations with pH are investigated here using a grand canonical Monte Carlo method. A Tanford and Kirkwood approach is used to calculate the interaction potentials between the discrete charged sites. Homogeneous, heterogeneous, and patch site distributions are considered to reproduce the various titrating site distributions at the solid/solution interface of spherical NPs. By considering Coulomb, salt, and image charges effects, results show that for different ionic concentrations, modifications of the dielectric constant of NPs having homogeneous and heterogeneous site distributions have little effect on their charging process. Thus, the reaction field, due to the presence of image charges, fully counterbalances the Coulomb interactions. This is not the case for patch distributions, where Coulomb interactions are not completely counterbalanced by the reaction field. Application of the present model to pyrogenic silica is also performed and comparison is made with published experimental data of titration curves at various ionic concentrations.  相似文献   

12.
An unusual aggregation phenomenon that involves positively charged poly(L-lysine) (PLL) and negatively charged gold nanoparticles (Au NPs) is reported. Discrete, submicrometer-sized spherical aggregates are found to form immediately upon combining a PLL solution with gold sol (diameter approximately 14 nm). These PLL-Au NP assemblies grow in size with time, according to light scattering experiments, which indicates a dynamic flocculation process. Water-filled, silica hollow microspheres (outer diameter approximately microns) are obtained upon the addition of negatively charged SiO2 NPs (diameter approximately 13 nm) to a suspension of the PLL-Au NP assemblies, around which the SiO2 NPs form a shell. Structural analysis through confocal microscopy indicates the PLL (tagged with a fluorescent dye) is located in the interior of the hollow sphere, and mostly within the silica shell wall. The hollow spheres are theorized to form through flocculation, in which the charge-driven aggregation of Au NPs by PLL provides the critical first step in the two-step synthesis process ("flocculation assembly"). The SiO2 shell can be removed and re-formed by decreasing and increasing the suspension pH about the point-of-zero charge of SiO2, respectively.  相似文献   

13.
The interaction between silver nanoparticles (Ag NPs) of different surface charge and surfactants relevant to the laundry cycle has been investigated to understand changes in speciation, both in and during transport from the washing machine. Ag NPs were synthesized to exhibit either a positive or a negative surface charge in solution conditions relevant for the laundry cycle (pH 10 and pH 7). These particles were characterized in terms of size and surface charge and compared to commercially laser ablated Ag NPs. The surfactants included anionic sodium dodecylbenzenesulfonate (LAS), cationic dodecyltrimethylammoniumchloride (DTAC) and nonionic Berol 266 (Berol). Surfactant-Ag NP interactions were studied by means of dynamic light scattering, Raman spectroscopy, zeta potential, and Quartz Crystal Microbalance. Mixed bilayers of CTAB and LAS were formed through a co-operative adsorption process on positively charged Ag NPs with pre-adsorbed CTAB, resulting in charge reversal from positive to negative zeta potentials. Adsorption of DTAC on negatively charged synthesized Ag NPs and negatively charged commercial Ag NPs resulted in bilayer formation and charge reversal. Weak interactions were observed for nonionic Berol with all Ag NPs via hydrophobic interactions, which resulted in decreased zeta potentials for Berol concentrations above its critical micelle concentration. Differences in particle size were essentially not affected by surfactant adsorption, as the surfactant layer thicknesses did not exceed more than a few nanometers. The surfactant interaction with the Ag NP surface was shown to be reversible, an observation of particular importance for hazard and environmental risk assessments.  相似文献   

14.
It has recently been shown that surface plasmon microscopy (SPM) allows single nanoparticles (NPs) on sensor surfaces to be detected and analyzed. The authors have applied this technique to study the adsorption of single metallic and plastic NPs. Binding of gold NPs (40, 60 and 100 nm in size) and of 100 nm polystyrene NPs to gold surfaces modified by differently ω-functionalized alkyl thiols was studied first. Self-assembled monolayers (SAM) with varying terminal functions including amino, carboxy, oligo(ethylene glycol), methyl, or trimethylammonium groups were deposited on gold films to form surfaces possessing different charge and hydrophobicity. The affinity of NPs to these surfaces depends strongly on the type of coating. SAMs terminated with trimethylammonium groups and carboxy group display highly different affinity and therefore were preferred when creating patterned charged surfaces. Citrate-stabilized gold NPs and sulfate-terminated polystyrene NPs were used as negatively charged NPs, while branched polyethylenimine-coated silver NPs were used as positively charged NPs. It is shown that the charged patterned areas on the gold films are capable of selectively adsorbing oppositely charged NPs that can be detected and analyzed with an ~1 ng?mL?1 detection limit.
Graphical abstract Self-assembled monolayers of ω-functionalized alkyl thiols were deposited on a gold layer of a patterned sensor array. The charge-selective binding of single nanoparticles to such surfaces was registered by wide-field surface plasmon microscopy.
  相似文献   

15.
Bimetallic nanoparticles (NPs) are known to exhibit enhanced optical and catalytic properties that can be optimized by tailoring NP composition, size, and morphology. Galvanic deposition of a second metal onto a primary metal NP template is a versatile method for fabricating bimetallic NPs using a scalable, solution-based synthesis. We demonstrate that the galvanic displacement reaction pathway can be controlled through appropriate surface modification of the NP template. To synthesize bimetallic Au-Ag NPs, we used colloidal Ag NPs modified by layer-by-layer (LBL) assembled polyelectrolyte layers to template the reduction of HAuCl(4). NPs terminated with positively and negatively charged polyelectrolytes yield highly contrasting morphologies and Au surface concentrations. We propose that these charged surface layers control galvanic charge transfer by controlling nucleation and diffusion at the deposition front. This surface-directed synthetic strategy can be advantageously used to tailor both overall NP morphology and Au surface concentrations.  相似文献   

16.
A systematic study of the adsorption of charged nanoparticles at dispersed oil-in-water emulsion interfaces is presented. The interaction potentials for negatively charged hexadecane droplets with anionic polystyrene latex particles or cationic gold particles are calculated using DLVO theory. Calculations demonstrate that increased ionic strength decreases the decay length of the electrostatic repulsion leading to enhanced particle adsorption. For the case of anionic PS latex particles, the energy barrier for particle adsorption is also reduced when the surface charge is neutralized through changes in pH. Complementary small-angle scattering experiments show that the highest particle adsorption for PS latex occurs at moderate ionic strength and low pH. For cationic gold particles, simple DLVO calculations also explain scattering results showing that the highest particle adsorption occurs at neutral pH due to the electrostatic attraction between oppositely charged surfaces. This work demonstrates that surface charges of particles and oil droplets are critical parameters to consider when engineering particle-stabilized emulsions.  相似文献   

17.
The colloidal behavior of aluminum oxide nanoparticles (NPs) was investigated as a function of pH and in the presence of two structurally different humic acids (HAs), Aldrich HA (AHA) and the seventh HA fraction extracted from Amherst peat soil (HA7). Dynamic light scattering (DLS) and atomic force microscopy (AFM) were employed to determine the colloidal behavior of the NPs. Influence of pH and HAs on the surface charges of the NPs was determined. zeta-Potential data clearly showed that the surface charge of the NPs decreased with increasing pH and reached the point of zero charge (ZPC) at pH 7.9. Surface charge of the NPs also decreased with the addition of HAs. The NPs tend to aggregate as the pH of the suspension approaches ZPC, where van der Waals attraction forces dominate over electrostatic repulsion. However, the NP colloidal suspension was stable in the pHs far from ZPC. Colloidal stability was strongly enhanced in the presence of HAs at the pH of ZPC or above it, but in acidic conditions NPs showed strong aggregation in the presence of HAs. AFM imaging revealed the presence of long-chain fractions in HA7, which entangled with the NPs to form large aggregates. The association of HA with the NP surface can be assumed to follow a two-step process, possibly the polar fractions of the HA7 sorbed on the NP surface followed by entanglement with the long-chain fractions. Thus, our study demonstrated that the hydrophobic nature of the HA molecules strongly influenced the aggregation of colloidal NPs, possibly through their conformational behavior in a particular solution condition. Therefore, various organic matter samples will result in different colloidal behavior of NPs, subsequently their environmental fate and transport.  相似文献   

18.
The surface site distribution and the dielectric discontinuity effects on the charging process of a spherical nanoparticle (NP) have been investigated. It is well known that electrostatic repulsion between charges on neighbouring sites tends to decrease the effective charge of a NP. The situation is more complicated close to a dielectric breakdown, since here a charged site is not only interacting with its neighbours but also with its own image charge and the image charges of all its neighbours. Coexistence of opposite charges, titration sites positions, and pH dependence are systematically studied using a grand canonical Monte Carlo method. A Tanford and Kirkwood approach has been applied to describe the interaction potentials between explicit discrete ampholytic charging sites. Homogeneous, heterogeneous and patch site distributions were considered to reproduce the titration site distribution at the solid/solution interface of natural NPs. Results show that the charging process is controlled by the balance between Coulomb interactions and the reaction field through the solid-liquid interface. They also show that the site distribution plays a crucial role in the charging process. In patch distributions, charges accumulate at the perimeter of each patch due to finite size effects. When homogeneous and heterogeneous distributions are compared, three different charging regimes are obtained. In homogeneous and heterogeneous (with quite low polydispersity indexes) distributions, the effects of the NP dielectric constant on Coulomb interactions are counterbalanced by the reaction field and in this case, the dielectric breakdown has no significant effect on the charging process. This is not the case in patch distributions, where the dielectric breakdown plays a crucial role in the charging process.  相似文献   

19.
Integrated analytical techniques were used to study the tissue distribution and structural information of gold nanorods (Au NRs) in Sprague-Dawley rats through tail intravenous injection. Before in vivo experiments were conducted, careful characterization of Au NRs was performed. The zeta potential proved that adsorption of bovine serum albumin on Au NRs turned the surface charges from positive to negative as in an in vitro simulation. The biodistribution of Au NRs was investigated quantitatively by inductively coupled plasma mass spectrometry at different time points after injection. As target tissues, both liver and spleen were chosen to further demonstrate the intracellular localization of Au NRs by the combination of transmission electron microscopy and energy-dispersive X-ray spectroscopy. Moreover, synchrotron-radiation-based X-ray absorption spectroscopy was employed and it was observed that long-term retention of Au NRs in liver and spleen did not induce obvious changes in the oxidation states of gold. Therefore, the present systematic method can provide important information about the fates of Au NRs in vivo and can also be extended to study the biological effects of other metallic nanomaterials in the future.   相似文献   

20.
Solutions containing oppositely charged nanoparticles (NPs) deposit "patchy" coatings of alternating charge distribution on various types of materials, including polymers, elastomers, and semiconductors. Surface adsorption of the NPs is driven by cooperative electrostatic interactions and does not require chemical ligation or layer-by-layer schemes. The composition and the quality of the coatings can be regulated by the types, the charges, and the relative concentrations of the NPs used and by the pH. Dense coatings form on flat, curvilinear, or micropatterned surfaces, are stable against common chemicals for prolonged periods of time, and can be used in applications ranging from bacterial protection to plasmonics.  相似文献   

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