胞苷保护的铜纳米簇新型荧光探针检测重铬酸根离子

基于重铬酸根离子(Cr_2O_7~(2-))对胞苷保护的荧光铜纳米簇(Cu NCs)的猝灭作用,构建了一种可用于检测Cr_2O_7~(2-)的荧光传感器.实验结果表明,该传感体系检测Cr_2O_7~(2-)的线性范围为0.05~7.0μmol/L,检出限为24 nmol/L(S/N=3).该传感器对Cr_2O_7~(2-)的检测具有良好的选择性,可用于湖水样中Cr_2O_7~(2-)的检测.     

Theranostic gold cluster nanoassembly for simultaneous enhanced cancer imaging and photodynamic therapy

As one of near-infrared (NIR) fluorescent (FL) nanoprobes, gold nanoclusters (Au NCs) are delicated to passive-targeting tumors for NIR FL imaging, but which easily cleared by the kidneys for the small size (<1.5 nm). Herein, the well-defined gold clusters nanoassembly (Au CNA) was synthesized by the selfassembly of Au NCs based on protein cross-linking approach. The as-prepared Au CNA demonstrated highly effective cellular uptake and precise tumor targeting compared to that of Au NCs. Moreover, with the irradiation of 660 nm laser, Au CNA generated largely reactive oxygen species (ROS) for photodynamic therapy (PDT). In vitro and in vivo PDT revealed that Au CNA exhibited largely cell death and significantly tumor removal at a low power density of 0.2 W/cm². It could be speculated that the laser-excited Au CNA produced photon energy, which further obtained electron from oxygen to generate radical species. Therefore, Au CNA as a photosensitizer could realize NIR FL imaging and NIR laser induced PDT.     

Control of the Fluorescence of DNA‐templated Silver Nanoclusters by Adenosine Triphosphate and Mercury(II)

Several DNA templates with the sequence 5′‐T _n TAACCCCTAACCCCT ‐3′ (n = 0, 15, 30, and 45) were used to prepare DNA template–silver nanoclusters (DNA –Ag NCs ). The T _n sequence acts as a recognition element for Hg²⁺, while the rest of the sequence acts as a template for DNA –Ag NCs . At pH 3.0, the fluorescence intensity of DNA –Ag NCs is enhanced by ATP , and the enhanced fluorescence is quenched by Hg²⁺. The length of polyT shows a slight effect on the sensitivity for the detection of Hg²⁺ but almost no effect on the optical properties of DNA –Ag NCs . The fluorescence response of DNA –Ag NCs (T₁₅‐DNA –Ag NCs ) vs. Hg²⁺ concentration shows two linear ranges over 10–100 and 100–1000 nM , mainly because of the fluorescence quenching due to DNA conformational changes through T–Hg²⁺–T coordination and the formation of an amalgam with Ag NCs , respectively. The sensitivity of the T₁₅‐DNA –Ag NC probe was validated through the analysis of Hg²⁺ in spiked pond water. Based on the switch‐on and switch‐off fluorescence properties of T₁₅‐DNA –Ag NCs , an IMPLICATION logic gate was fabricated using the concentrations of ATP and Hg²⁺ as inputs and the fluorescence intensity at 585 nm as output.     

Theoretical study of the stability and properties of magic numbers (m = 5, n = 2) and (m = 6, n = 3) of bimetallic bismuth‐copper nanoclusters; Bim Cun

Inspired by the experimental discovery of magic numbers we present a first study using density functional theory for the structure and properties of neutral and cationic Bi₆Cu₃ and Bi₅Cu₂ clusters. Our results confirm predictions based on Wade's rules. The closed electron shells, characteristic of cationic clusters help impose enhanced stability, while also complying with Wade's rules. Charge distribution analysis, as well as electrostatic potential maps show that in almost all cases, Bi atoms donate charges to Cu atoms. According to the analysis of condensed Fukui indices, Cu atoms inside both clusters are not reactive. Contrastingly, Bi atoms are reactive and may be targeted by different types of attack. This study of the electronic properties may thus help to determine experimental strategies with the capacity to enhance the synthesis of catalysts.     

Electrochemical Sensor Based on a Novel Pt−Au Bimetallic Nanoclusters Decorated on Reduced Graphene Oxide for Sensitive Detection of Ofloxacin

Pt−Au nanoclusters decorated on the surface of reduced graphene oxide (rGO/Pt−Au) was facilely prepared by one‐pot electrochemical reduction. The morphology and composition of rGO/Pt−Au composites had been characterized by scanning electron microscopy (SEM) coupled with energy‐dispersive X‐ray spectrometry (EDX), fourier transform‐infrared spectroscopy (FT‐IR) and electrochemical methods. Ofloxacin is a member of synthetic quinolones which has been widely used for the treatment of common diseases in humans and animals. The performance of the rGO/Pt−Au nanocomposite toward the oxidation of ofloxacin was compared with the other similar nanostructures like rGO/Pt and rGO/Au. In the optimized conditions, two linear calibration curves were obtained, from 0.08 to 10 μM and 10 to 100 μM ofloxacin. A detection limit of 0.05 μM ofloxacin was observed at pH 5.7 for the GCE/rGO/Pt−Au. The proposed sensor was successfully applied to determine ofloxacin in tablets and human urine samples and the results were satisfactory.     

Facile preparation of chitin nanowhisker–gold nanocluster hybrids: effect of feeding ratio and surface amino group contents on gold absorption amount

Chitin nanowhiskers (ChNWs) hybridized with the densely adsorbed gold nanoclusters (AuNCs) were facilely prepared by a simple mixing of aqueous suspensions of ChNWs and AuNCs. Adsorption of AuNCs on the ChNW surface was confirmed by transmission electron microscopy and scanning electron microscopy with energy dispersive X‐ray spectroscopy. The amounts of adsorbed AuNCs measured by thermogravimetry and combustion using a muffle furnace were in good agreement. While the amount of adsorbed AuNCs increased with AuNCs/ChNWs feeding ratio, we found only a weak dependence of adsorbed AuNC amount on the surface amino group content of ChNWs controlled by pre‐deacetylation of the starting chitin. Copyright © 2016 John Wiley & Sons, Ltd.     

Nucleation and growth of Ge nanoclusters on the Si(111)‐(7 × 7) surface studied by scanning tunneling microscopy

Nucleation and growth of two‐dimensional Ge nanoclusters on the Si(111)‐(7 × 7) surface at elevated substrate temperatures have been studied using scanning tunneling microscopy. The uniformity of the Ge nanoclusters is improved with the increase of substrate temperature, and ordered Ge nanoclusters are formed on the faulted and unfaulted halves of (7 × 7) unit cell at substrate temperature of 200 °C. It is proposed that the Ge nanoclusters consist of six Ge atoms with three on top of the center adatoms and others on the rest atoms within one half of a unit cell. Copyright © 2014 John Wiley & Sons, Ltd.     

Label-free colorimetric sensor for mercury(II) and DNA on the basis of mercury(II) switched-on the oxidase-mimicking activity of silver nanoclusters

In this paper, a novel colorimetric biosensor for Hg²⁺ and DNA molecules is presented based on Hg²⁺ stimulated oxidase-like activity of bovine serum albumin protected silver clusters (BSA-Ag NCs). Under mild conditions, Hg²⁺ activated BSA-Ag NCs to show high catalytic activity toward the oxidation of 3,3′,5, 5′-tetramethylbenzidine (TMB) using ambient dissolved oxygen as an oxidant. The oxidase-like activity of BSA-Ag NCs was “switched-on” selectively in the presence of Hg²⁺, which permitted a novel and facile colorimetric sensor for Hg²⁺. As low as 25 nmol L⁻¹ Hg²⁺ could be detected with a linear range from 80 nmol L⁻¹ to 50 mmol L⁻¹. In addition, the sensing strategy was also employed to detect DNA molecules. Hg²⁺ is known to bind very strongly and specifically with two DNA thymine bases (T) to form thymine–Hg²⁺–thymine (T–Hg²⁺–T) base pairs. The hairpin-structure was disrupted and Hg²⁺ ions were released after hybridization with the DNA target. By coupling the Hg²⁺ switched-on the oxidase-mimicking activity of BSA-Ag NCs, we developed a novel label-free strategy for facile and fast colorimetric detection of DNA molecules. More important, target DNA can be detected as low as 10 nmol L⁻¹ with a linear range from 30 to 225 nmol L⁻¹. Compared with other methods, this method presents several advantages such as the independence of hydrogen peroxide, high sensitivity and good selectivity, avoiding any modification or immobilization of DNA, which holds a great potential of metal NCs for clinical application in biosensing and biotechnology.     

一锅法合成聚乙烯吡咯烷酮修饰的铜纳米团簇用于槲皮素的检测

作为检测槲皮素的有效途径,在荧光法中如何通过简单的方法合成性能优良的荧光探针具有重要的意义。 本文以聚乙烯吡咯烷酮(PVP)为保护剂,抗坏血酸为还原剂,化学还原法合成PVP保护的分散性好、稳定性高、强荧光的铜纳米团簇(PVP-Cu NCs)。 样品表现出良好的水溶性,光稳定性和强离子稳定性。 通过紫外可见光谱(UV-Vis)、分子荧光光谱、透射电子显微镜(TEM)和X射线光电子能谱分析(XPS)对铜纳米团簇的光学性质和结构进行了分析。 结果表明:该铜纳米团簇的最大激发和发射波长分别为366和429 nm,平均粒径大小为2 nm。 基于槲皮素对该铜纳米团簇的猝灭作用,构建了一种可用于检测槲皮素的荧光传感器。 该传感体系检测槲皮素的线性范围为0.1～0.9 μmol/L和15～60 μmol/L,检测限为0.053 μmol/L(S/N=3)。 该传感器对槲皮素的检测具有很高的灵敏度和良好的选择性,可用于实际样品中槲皮素的检测。     

超支化聚酰胺负载铂纳米簇杂化膜催化苯加氢反应

制备了一系列不同结构的超支化聚酰胺及其负载铂纳米簇杂化膜催化剂,研究了该催化剂对苯液相加氢反应的催化性能。利用透射电子显微镜、傅里叶变换红外光谱仪、X-射线衍射和X-射线光电子能谱等对铂纳米簇以及负载催化剂的结构进行了表征。结果表明：铂纳米颗粒分散均匀,粒径为3～5 nm;催化剂中的Pt与超支化聚酰胺上的N和O之间存在...