Fluorescent Gold Nanoparticles: Synthesis of Composite Materials of Two‐Component Disulfide Gels and Gold Nanoparticles

Pseudoenantiomeric ethynylhelicene oligomers containing a disulfide group formed two‐component gels, which showed different solvent properties from gels without the disulfide group. The disulfide gels reacted with gold nanoparticles, and the resulting organic–inorganic composite materials exhibited fluorescence emission between 600–800 nm, along with emission from the oligomers at 450 nm. The disulfide gels and isolated gold nanoparticles loaded with the oligomers did not show the former emission. The 600–800 nm emission reversibly disappeared upon sol formation with heating, which was accompanied by an enhancement of the emission at 450 nm. The novel emission was also observed in the solid state.     

金纳米粒子的细胞毒性

金纳米粒子(AuNPs)是构建用于诊断和治疗的纳米药物/探针的理想纳米材料之一,因此研究AuNPs与细胞的相互作用具有重要意义。 本文详细分析了金纳米簇(AuNCs)、球形金纳米粒子A(AuNPss)、金纳米球壳(AuNSs)和金纳米棒(AuNRs)等不同形貌的Au NPs对不同细胞模型的细胞毒性;讨论了AuNPs的理化性质(大小、形状、化学功能和表面电荷)对其细胞毒性的影响。 总结了AuNP细胞毒性研究遇到的挑战并提出相应解决方法。     

Role of Capping Ligands on the Nanoparticles in the Modulation of Properties of a Hybrid Matrix of Nanoparticles in a 2D Film and in a Supramolecular Organogel

We incorporate various gold nanoparticles (AuNPs) capped with different ligands in two‐dimensional films and three‐dimensional aggregates derived from N‐stearoyl‐L ‐alanine and N‐lauroyl‐L ‐alanine, respectively. The assemblies of N‐stearoyl‐L ‐alanine afforded stable films at the air–water interface. More compact assemblies were formed upon incorporation of AuNPs in the air–water interface of N‐stearoyl‐L ‐alanine. We then examined the effects of incorporation of various AuNPs functionalized with different capping ligands in three‐dimensional assemblies of N‐lauroyl‐L ‐alanine, a compound that formed a gel in hydrocarbons. The profound influence of nanoparticle incorporation into physical gels was evident from evaluation of various microscopic and bulk properties. The interaction of AuNPs with the gelator assembly was found to depend critically on the capping ligands protecting the Au surface of the gold nanoparticles. Transmission electron microscopy (TEM) showed a long‐range directional assembly of certain AuNPs along the gel fibers. Scanning electron microscopy (SEM) images of the freeze‐dried gels and nanocomposites indicate that the morphological transformation in the composite microstructures depends significantly on the capping agent of the nanoparticles. Differential scanning calorimetry (DSC) showed that gel formation from sol occurred at a lower temperature upon incorporation of AuNPs having capping ligands that were able to align and noncovalently interact with the gel fibers. Rheological studies indicate that the gel–nanoparticle composites exhibit significantly greater viscoelasticity compared to the native gel alone when the capping ligands are able to interact through interdigitation into the gelator assembly. Thus, it was possible to define a clear relationship between the materials and the molecular‐level properties by means of manipulation of the information inscribed on the NP surface.     

水助催化氢分子在金纳米粒子上解离的理论研究

金纳米粒子（GNPs）对氢分子（H₂）的解离具有良好的催化活性. 本文研究了水分子对 GNPs 催化 H₂ 解离的影响. 对于H₂在中性和带正电的金簇（Au_n^δ,n=3~5;δ = 0,1）上的反应,考虑当水簇（(H₂O)_m,m = 1, 2, 3, 7）参与反应时 GNPs 催化H₂的解离过程的热力学和动力学. 研究结果表明,水对 H₂ 在GNPs上的解离有助催化的作用,且水簇大小不同,水助催化 H₂ 在金簇上解离的机理也有所不同,其由氢氢键的均裂解离转化为氧化解离. 对两种机理所得的产物,作者计算了它们的 Raman 和 IR 光谱.     

Amphiphilic Polymer Nanoparticles: Characterization and Assessment as New Drug Carriers

An amino‐acid‐based hydrophobically modified biocompatible copolymer, poly[(sodium N‐acryloyl‐L ‐valinate)‐co‐(N‐octylacrylamide)] was synthesized and characterized. Techniques such as fluorescence probes, DLS, and TEM were used to investigate its aggregation behavior in aqueous solution. The copolymer was observed to form micellar aggregates having diameters in the nanometer range in aqueous solution (pH = 8) through inter‐chain hydrophobic association. This behavior was found to be similar to that of poly[(sodium N‐acryloyl‐L ‐valinate)‐co‐(N‐dodecylacrylamide)]. The compact micellar nanostructures were observed to be stable with respect to changes of pH and temperature. The encapsulation and release of griseofulvin, a hydrophobic model drug, was studied.

     

Bioconjugation of Interferon-alpha Molecules to Lysine-Capped Gold Nanoparticles for Further Drug Delivery Applications

Gold nanoparticles are potentially very attractive components for therapeutic delivery since they can be synthesized with any diameter from 1 to 200 nm to carry a payload of therapeutic molecules into a cell without triggering an immune response. Gold nanoparticles must undergo surface transformations before coupling to therapeutic molecules to become eligible for this purpose. It is now more understood that amine groups can bind to gold nanoparticles strongly, which has enabled surface modification of gold nanoparticles with amino acid lysine through its amine group. These lysine capped gold nanoparticles can further be coupled to therapeutic molecules for delivery purposes. In this study gold nanoparticles were first synthesized and capped with lysine molecules. TEM and FTIR measurements demonstrated the synthesis of lysine-capped gold nanoparticles with an average diameter of 10 nanometers. Interferon alpha molecules-one of the most important therapeutic protein were then chemically bound to lysine-capped gold nanoparticles through a two-step process of diimide-activated amidation. The conjugation of interferon molecules to lysine capped gold nanoparticles was carried out via the reaction between the free amine group of lysine and carboxyl groups of interferon using N-ethyl-N′-13-dimethyl-aminopropyl (EDAC) as a coupling agent. The process of conjugation has also been studied by transmission electron microscopy.     

Parametric Study of Gold Nanoparticles Synthesis under Micro-Continuous Flow Conditions

The synthesis of gold nanoparticles (GNPs) using chemical reduction in batch and microreactor methods has been reported. A parametric study of the effect of several parameters on the size of gold nanoparticles was performed in batch synthesis mode using the modified Martin method. The best-obtained conditions were used to synthesize gold nanoparticles using a glass chip microreactor, and the size of the resulting GNPs from both methods was compared. The presence of polyvinyl alcohol (SC) was used as a capping agent, and sodium borohydride (SB) was used as a reducing agent. Several parameters were studied, including HAuCl₄, SC, SB concentrations, the volumetric ratio of SB to gold precursor, pH, temperature, and mixing speed. Various techniques were used to characterize the resulting nanoparticles, including Atomic Absorbance spectroscopy (AAS), Ultraviolet-visible spectroscopy (UV-Vis), and dynamic light scratching (DLS). Optimum conditions were obtained for the synthesis of gold nanoparticles. Under similar reaction conditions, the microreactor consistently produced smaller nanoparticles in the range of 10.42–11.31 nm with a reaction time of less than 1 min.     

Controlled Self-Assembly of Metallacycle-Bridged Gold Nanoparticles for Surface-Enhanced Raman Scattering

In this work, well-defined two-dimensional metallacycles have been successfully employed for the well-controlled self-assembly of gold nanoparticles (AuNPs) into discrete clusters such as dimers, trimers, tetramers, pentamers and even hexamers at the water–oil interface for the first time. Furthermore, the modular construction of metallacycle molecules allows precise control of spacing between the gold nanoparticles. Interestingly, it was found that interparticle spacing below 5 nm created by molecular metallacycles in the resultant discrete gold nanoparticle clusters led to a strong plasmon coupling, thus inducing great field enhancement inside the gap between the NPs. More importantly, different discrete clusters with precise interparticle spacing provide a well-defined system for studying the hot-spot phenomenon in surface-enhanced Raman scattering (SERS); this revealed that the SERS effects were closely related to the interparticle spacing.     

金粒子包封介孔二氧化硅杂化载药控释体系

靶向给药控释体系既可以增强药物在病灶部位的疗效, 又可以降低药物对正常部位的毒副作用. 基于介孔二氧化硅为"容器"-金纳米粒子为"开关"(MSN-AuNPs)的杂化纳米阀门体系同时具备两种纳米粒子的优良特性, 在化学、生物材料以及临床医药等多学科受到广泛关注. 本文根据刺激手段和应用功能分类, 介绍了单一功能和多重功能的MSN-AuNPs杂化纳米阀门体系的重要研究进展, 以及目前面临的挑战和今后的发展方向.     

甲烷氧化菌素催化纳米金合成

甲烷氧化菌素(methanobactin,mb)是具有过氧化氢还原酶活性的荧光肽.从甲基弯菌Methylosinus trichospo-rium IMV3011限铜培养介质中分离mb,采用紫外可见全波长扫描法观察mb催化对苯二酚还原氯金酸合成纳米金的作用和影响,当mb/氯金酸/对苯二酚反应液中mb的浓度分别是2.5×10-5mol/L、5.0×10-5mol/L和1.0×10-4mol/L时,形成的纳米金溶液的特征峰分别是561.5 nm(OD561=0.158)、548.0 nm(OD5 48=0.426)、536.5 nm(OD5 36=0.541),特征峰波长减小,对应的吸光值增大,表明mb能够催化对苯二酚还原氯金酸合成纳米金,并且可以通过调控mb的浓度控制纳米金的合成量及粒径大小.     

Characterization of Labeled Gold Nanoparticles for Surface-Enhanced Raman Scattering

Noble metal nanoparticles (NP) such as gold (AuNPs) and silver nanoparticles (AgNPs) can produce ultrasensitive surface-enhanced Raman scattering (SERS) signals owing to their plasmonic properties. AuNPs have been widely investigated for their biocompatibility and potential to be used in clinical diagnostics and therapeutics or combined for theranostics. In this work, labeled AuNPs in suspension were characterized in terms of size dependency of their localized surface plasmon resonance (LSPR), dynamic light scattering (DLS), and SERS activity. The study was conducted using a set of four Raman labels or reporters, i.e., small molecules with large scattering cross-section and a thiol moiety for chemisorption on the AuNP, namely 4-mercaptobenzoic acid (4-MBA), 2-naphthalenethiol (2-NT), 4-acetamidothiophenol (4-AATP), and biphenyl-4-thiol (BPT), to investigate their viability for SERS tagging of spherical AuNPs of different size in the range 5 nm to 100 nm. The results showed that, when using 785 nm laser excitation, the SERS signal increases with the increasing size of AuNP up to 60 or 80 nm. The signal is highest for BPT labelled 80 nm AuNPs followed by 4-AATP labeled 60 nm AuNPs, making BPT and 4-AATP the preferred candidates for Raman labelling of spherical gold within the range of 5 nm to 100 nm in diameter.     

Activating the Antibacterial Effect of 4,6-Diamino-2-pyrimidinethiol-Modified Gold Nanoparticles by Reducing their Sizes

Adequately decorated gold nanoparticles (GNPs) have excellent antibiotic activities against multidrug-resistant (MDR) bacteria. Nanoparticles exhibiting Gram selective antibacterial actions are beneficial to precise therapy. Here, we present a strategy to tune the antibacterial spectrum of a small molecule (4,6-diamino-2-pyrimidinethiol, DAPT)-modified GNPs (DAPT-GNPs, DGNPs) by adjusting their sizes. Compared to large (ca. 14 nm diameter) DGNPs (lDGNPs) and medium-sized (3–4 nm diameter) DGNPs (mDGNPs), which have no antibacterial effect or only target Gram-negative (G−) bacteria, ultrasmall DGNPs (uDGNPs, <2 nm) have a broad antibacterial spectrum, especially showing an over 60-fold increase in antibacterial efficacy against Gram-positive (G+) bacteria. Moreover, the uDGNPs-functionalized scaffolds (agarose gel) can serve as general wound dressings for healing burnt infections. Our strategy is insightful for exploring properties of the nanomaterials and their applications.     

Ribbon of DNA Lattice on Gold Nanoparticles for Selective Drug Delivery to Cancer Cells

Herein, we report on the design of a programmable DNA ribbon using long‐chain DNA molecules with a user‐defined repetitive padlock sequence. The DNA ribbon can be further combined with gold nanoparticles (AuNPs) to create a composite nanomaterial that contains an AuNP core and a high‐density DNA crown carrying a cancer‐cell‐targeting DNA aptamer, a fluorescent tag for location tracking, and a cell‐killing drug. This composite material can be efficiently internalized by cancer cells and its cellular location can be tracked by fluorescence imaging. The system offers several attractive characteristics, including simple design, tunable DNA crown, high drug‐loading capacity, selective cell targeting, and pH‐sensitive drug release. These features make such a material a promising therapeutic agent.     

纳米金增强低温等离子体离子化质谱快速检测苯胺

低温等离子体(Low-temperature plasma,LTP)作为敞开式离子源满足环境检测要求的样品原位、快速检测,然而水体的基体效应使得检测灵敏度不足。该文将金纳米颗粒溅射于针灸针表面后,结合低温等离子体离子源进行检测,实现了质谱信号的增强效应,可以快速灵敏检测水体中的苯胺。结果表明,相比于无纳米金修饰的针尖,苯胺检测信号强度增强了43倍,且具有较低的背景噪音。苯胺的质量浓度与质谱信号强度在1~50μg/L范围内呈线性关系,检出限(LOD)为0.64μg/L,每个样品检测时间约为1 min。该方法简单易操作,结合便携式质谱有望用于环境水体及突发性水源污染事件中苯胺的检测。     

应用磁金纳米粒子研究牛血清白蛋白与牛蒡子苷之间的相互作用

建立了用于确定血清白蛋白与中药有效成分相互作用结合常数和结合位点数的新方法.利用磁金纳米粒子的超顺磁性和生物相容性,将其作为白蛋白的载体.将牛血清白蛋白固定在磁金纳米粒子上,白蛋白与药物结合后,通过外加磁场将磁金纳米粒子-白蛋白-药物复合物与游离药物分离,通过荧光光谱法得到的游离药物浓度,根据Scatchard方程直接计算出白蛋白与药物的结合常数和结合位点数.本方法用于研究牛血清白蛋白和牛蒡子苷之间的相互作用,结合常数为2.09×105 L/mol,结合位点数为16.63.通过外加磁场作用,使白蛋白从样品溶液中分离出来,样品溶液中只有药物,消除了测定药物时白蛋白的影响,因此所求得的结合位点的数目更准确.实验结果表明,本方法可用于测定分子间非共价结合的结合常数和结合位点数,同时为研究中药有效成分与血清白蛋白相互作用提供了参考.     

Synthesis,Chemical–Physical Characterization,and Biomedical Applications of Functional Gold Nanoparticles: A Review

Relevant properties of gold nanoparticles, such as stability and biocompatibility, together with their peculiar optical and electronic behavior, make them excellent candidates for medical and biological applications. This review describes the different approaches to the synthesis, surface modification, and characterization of gold nanoparticles (AuNPs) related to increasing their stability and available features useful for employment as drug delivery systems or in hyperthermia and photothermal therapy. The synthetic methods reported span from the well-known Turkevich synthesis, reduction with NaBH₄ with or without citrate, seeding growth, ascorbic acid-based, green synthesis, and Brust–Schiffrin methods. Furthermore, the nanosized functionalization of the AuNP surface brought about the formation of self-assembled monolayers through the employment of polymer coatings as capping agents covalently bonded to the nanoparticles. The most common chemical–physical characterization techniques to determine the size, shape and surface coverage of AuNPs are described underlining the structure–activity correlation in the frame of their applications in the biomedical and biotechnology sectors.     

Polysorbate 80 as a Tool: Synthesis of Gold Nanoparticles

The preparation of metal nanoparticles generally requires the use of mostly toxic reducing agents according to state‐of‐the‐art procedures. Here, we report that polysorbate 80, a polymeric nonionic surfactant, when reacted with a gold salt in water at room temperature, yields well‐dispersed gold nanoparticles. Furthermore, we could control the particle size by simply altering concentration or temperature. The synthetic procedure presented here is easy, inexpensive, straightforward, and user‐friendly.

     

纳米金催化鲁米诺化学发光体系测定甲巯咪唑

在碱性介质中,甲巯咪唑能强烈增敏纳米金-鲁米诺-硝酸银化学发光体系产生较强的化学发光信号,据此建立了一种流动注射化学发光测定甲巯咪唑的新方法。在优化实验条件下,该方法对甲巯咪唑的检测线性范围为1.0×10-9~1.0×10-8、1.0×10-8~1.0×10-7、1.0×10-7~1.0×10-6g/mL,检出限(S/N=3)为3.0×10-10g/mL,相对标准偏差为1.2%(n=11,ρ=1.0×10-8g/mL)。将该法用于药物中甲巯咪唑含量的测定,结果满意。同时,采用化学发光光谱表征技术对该体系的化学发光反应机理进行了初步探讨。     

铜离子配位甲烷氧化菌素功能化纳米金模拟过氧化物酶的研究

合成了纳米金-甲烷氧化菌素(Mb)-铜配合物,该配合物可以作为模拟过氧化物酶用于催化过氧化氢氧化对苯二酚的反应.通过紫外光谱、荧光光谱、红外光谱对纳米金-甲烷氧化菌素(Mb)-铜进行了表征.利用紫外-可见分光光度法研究了配合物催化过氧化氢氧化对苯二酚的动力学.考察了体系p H、体系温度及过氧化氢/催化剂摩尔比对催化反应速率的影响.结果表明纳米金-甲烷氧化菌素(Mb)-铜配合物符合生物催化剂条件影响的一般规律,但比生物酶具有更高的热稳定性.