Inorganic–Organic Hybrid Nanoparticles with Biocompatible Calcium Phosphate Thin Shells for Fluorescence Enhancement

Polymeric micelles consisting of asymmetric triblock copolymers were successfully used for fabrication of robust hybrid nanoparticles with highly biocompatible calcium phosphate shells. The hydrophobic polystyrene core encapsulates hydrophobic fluorescent dyes such as Nile red. The anionic polyacrylic acid provides the site for the mineralization reaction of calcium phosphate. The polyethylene glycol corona stabilizes the hybrid nanoparticles. Fluorescent dyes can be used as imaging agents for determining the location of the nanoparticles and to give an observable indication of drug delivery, while the calcium phosphate shell can enhance the fluorescence of the encapsulated dye.     

Versatile Probes for the Selective Detection of Vicinal‐Dithiol‐Containing Proteins: Design,Synthesis, and Application in Living Cells

Endogenous vicinal‐dithiol‐containing proteins (VDPs) that have two thiol groups close to each other in space play a significant importance in maintaining the cellular redox microenvironment. Approaches to identify VDPs mainly rely on monitoring the different concentration of monothiol and total thiol groups or on indirect labeling of vicinal thiols by using p‐aminophenylarsenoxide ( PAO ). Our previous work has reported the direct labeling of VDPs with a highly selective receptor PAO analogue, which could realize fluorescence detection of VDPs directly in living cells. Herein, we developed a conjugated approach to expand detectable tags to nitrobenzoxadiazole (NBD), fluorescein, naphthalimide, and biotin for the synthesis of a series of probes. Different linkers have also been introduced toward conjugation of VTA2 with these functional tags. These synthesized flexible probes with various features will offer new tools for the potential identification and visualization of vicinal dithiols existing in different regions of VDPs in living cells. These probes are convenient tools for proteomics studies of various disease‐related VDPs and for the discovery of new drug targets.     

Gold Nanoparticle–Fluorophore Complexes: Sensitive and Discerning “Noses” for Biosystems Sensing

Gold nanoparticles (NPs) efficiently quench adsorbed fluorophores. Upon disruption of such complexes by an analyte, fluorescence turn‐on is observed. By judicious choice of the functionalized NP and the fluorophore, these complexes display different responses to analytes, thus leading to versatile yet simple array‐based sensor platforms. Using this strategy, we can identify proteins in buffer and serum, distinguish between both different species and different strains of bacteria, and differentiate between healthy, cancerous, and metastatic human and murine cells.     

Electrochemical Preparation and Delivery of Melanin–Iron Covered Gold Nanoparticles

Attractive combination: Biopolymer‐modified nanoparticles which combine magnetic properties with biocompatibility are prepared and delivered following a three‐step strategy (see figure): i) Adsorption of thiol‐capped metal nanoparticles on graphite, ii) electrochemical modification, iii) potential‐induced delivery of the modified nanoparticles to the electrolyte.

     

Multifunctional manganese carbonate microspheres with superparamagnetic and fluorescent properties: synthesis and biological application

Multifunctional manganese carbonate microspheres with superparamagnetic and fluorescent properties were fabricated and used as biological labels. The Fe(3)O(4)@MnCO(3) microspheres were synthesized by direct co-precipitation without any linker shell. The Fe(3)O(4)@MnCO(3) microspheres have uniform size distribution and rough surface, which provides a promising template for the assembly of polyelectrolytes (PEs) and CdTe quantum dots (QDs). A luminescent CdTe shell was observed in Fe(3)O(4)@MnCO(3)@PE-CdTe spheres by confocal fluorescence imaging. With excellent solubility in water and rough surfaces, the multifunctional microsphere offers a friendly microenvironment for immobilization of α-fetoprotein (AFP) antibodies (Ab(2)) to fabricate Fe(3)O(4)@MnCO(3)@PE-CdTe-Ab(2) architecture. By using the Fe(3)O(4) @MnCO(3)@PEs-CdTe-Ab(2) bioconjugate as a label, a promising and versatile platform for fluorescence imaging and electrochemical immunosensing of cancer biomarker AFP was developed. The prepared electrochemical immunosensor shows high sensitivity and selectivity with a detection limit of 0.3 pg mL(-1).     

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.     

聚苯胺包裹的金纳米粒子的合成和表征及初步应用

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.     

纳米碳酸钙的生产和用途

碳酸钙是自然界广泛存在的一种很普通的非金属材料,也是一种传统的无机盐化工产品。近年来,随着碳酸钙的超细化及表面改性技术的发展,纳米碳酸钙制备技术及应用,已成为国内外竞相开发的研究热点。本文就有关纳米碳酸钙的主要生产技术及其应用领域作一简介。     

Synthesis of Water‐Soluble Red‐Emitting Thienyl–BODIPYs and Bovine Serum Albumin Labeling

Thesynthesis of three red‐emitting and water‐soluble thienyl‐BODIPYs has beenachieved. The trimethyl(propargyl)ammonium group was chosen as a vector forwater solubility. One or two cationic arms were introduced either on the2‐position of the thienyl unit or on the 4‐position on the boron atom. Thesedyes have pronounced absorption around 600 nm and intense emission at 650 nmwith quantum yield of about 60% in water. Grafting of such BODIPYs via a flexible arm to BSA is veryefficient, allowing attachment of 1 to 30 labels in a controlled manner.  Very strong fluorescence (quantum yield 56%)without aggregation of the dye at a low loading ratio (1:5 BSA/label) in PBSbuffer is measured.     

Dual Enhancement of Gold Nanocluster Electrochemiluminescence: Electrocatalytic Excitation and Aggregation‐Induced Emission

Ligand‐protected gold nanoclusters (AuNCs) have emerged as a new class of electrochemiluminescence (ECL) luminophores for their interesting catalytic and emission properties, although their quantum yield (Φ_ECL) in aqueous medium is low with a poor mechanistic understanding of the ECL process. Now it is shown that drying AuNCs on electrodes enabled both enhanced electrochemical excitation by an electrocatalytic effect, and enhanced emission by aggregation‐induced ECL (AIECL) for 6‐aza‐2‐thiothymine (ATT) protected AuNCs with triethylamine (TEA) as a coreactant. The dried ATT‐AuNCs/TEA system resulted in highly stable visual ECL with a Φ_ECL of 78 %, and a similar enhancement was also achieved with methionine‐capped AuNCs. The drying enabled dual‐enhancement mechanism has solved a challenging mechanistic problem for AuNC ECL probes, and can guide further rational design of ECL emitters.     

Hybridization‐Sensitive On–Off DNA Probe: Application of the Exciton Coupling Effect to Effective Fluorescence Quenching

The design of dyes that emit fluorescence only when they recognize the target molecule, that is, chemistry for the effective quenching of free dyes, must play a significant role in the development of the next generation of functional fluorescent dyes. On the basis of this concept, we designed a doubly fluorescence‐labeled nucleoside. Two thiazole orange dyes were covalently linked to a single nucleotide in a DNA probe. An absorption band at approximately 480 nm appeared strongly when the probe was in a single‐stranded state, whereas an absorption band at approximately 510 nm became predominant when the probe was hybridized with the complementary strand. The shift in the absorption bands shows the existence of an excitonic interaction caused by the formation of an H aggregate between dyes, and as a result, emission from the probe before hybridization was suppressed. Dissociation of aggregates by hybridization with the complementary strand resulted in the disruption of the excitonic interaction and strong emission from the hybrid. This clear change in fluorescence intensity that is dependent on hybridization is useful for visible gene analysis.     

Pluronics‐Stabilized Gold Nanoparticles: Investigation of the Structure of the Polymer–Particle Hybrid

Hybrid gold–polymer nanoparticles are obtained by self‐assembly of amphiphilic copolymers (Pluronics) in solutions containing preformed gold nanoparticles (diameter ca. 12 nm). Dynamic light scattering, TEM, cryo‐TEM, and small‐angle neutron scattering experiments with contrast variation are used to characterize the structure of the gold–polymer particles. Five Pluronics (F127, F68, F88, F108, P84) with different molecular weights and hydrophilic/hydrophobic balances are investigated. Gold nanoparticles are individually embedded within globules of polymer, even under conditions for which Pluronics micelles do not form in solution. The hybrid particles are several tens of nanometers in size (larger than micelles of the corresponding Pluronics), and the size can be tuned by changing the temperature.     

Efficient Tandem Synthesis of Methyl Esters and Imines by Using Versatile Hydrotalcite‐Supported Gold Nanoparticles

Efficient basic hydrotalcite (HT)‐supported gold nanoparticle (AuNP) catalysts have been developed for the aerobic oxidative tandem synthesis of methyl esters and imines from primary alcohols catalyzed under mild and soluble‐base‐free conditions. The catalytic performance can be fine‐tuned for these cascade reactions by simple adjustment of the Mg/Al atomic ratio of the HT support. The one‐pot synthesis of methyl esters benefits from high basicity (Mg/Al=5), whereas moderate basicity greatly improves imine selectivity (Mg/Al=2). These catalysts outperform previously reported AuNP catalysts by far. Kinetic studies show a cooperative enhancement between AuNP and the surface basic sites, which not only benefits the oxidation of the starting alcohol but also the subsequent steps of the tandem reactions. To the best of our knowledge, this is the first time that straightforward control of the composition of the support has been shown to yield optimum AuNP catalysts for different tandem reactions.     

Solvothermal Synthesis of a Novel Calcium Metal-Organic Framework: High Temperature and Electrochemical Behaviour

The rapid growth in the field of metal-organic frameworks (MOFs) over recent years has highlighted their high potential in a variety of applications. For biological and environmental applications MOFs with low toxicity are vitally important to avoid any harmful effects. For this reason, Ca-based MOFs are highly desirable owing to their low cost and high biocompatibility. Useful Ca MOFs are still rare owing to the ionic character and large size of the Ca²⁺ ion tending to produce dense phases. Presented here is a novel Ca-based MOF containing 2,3-dihyrdoxyterephthalate (2,3-dhtp) linkers Ca(2,3-dhtp)(H₂O) (SIMOF-4). The material undergoes a phase transformation on heating, which can be followed by variable temperature powder X-ray diffraction. The structure of the high temperature form was obtained using single-crystal X-ray diffraction. The electrochemical properties of SIMOF-4 were also investigated for use in a Na ion battery.     

金纳米粒子-壳聚糖-石墨烯纳米复合材料的制备及其在生物电化学中的应用

通过共价键作用和原位还原法制备了金纳米粒子/壳聚糖-石墨烯纳米复合材料(AuNPs/Chit-GP). 利用FT-IR, UV-vis, TEM以及XRD对所合成的纳米复合物的结构和形貌进行了表征. AuNPs/Chit-GP呈现明显的正电荷, 因此可通过静电相互作用固载葡萄糖氧化酶(GOD), 并构建GOD/AuNPs/Chit-GP/GC修饰电极. 该修饰电极不仅可成功地实现GOD与电极间的直接电子转移, 还对葡萄糖表现出良好的催化性能. 实验结果表明, 其催化的线性范围为2.1～5.7 μmol/L, 检出限为0.7 μmol/L, 灵敏度为79.71 mA·cm^-2·mM^-1. 这种集金属纳米粒子、生物相容性高分子以及石墨烯为一体的纳米复合物的构筑为无媒介体的电化学生物传感器的研究提供了一个良好的平台.     

Ionic Liquid Assisted Synthesis of Au–Pd Bimetallic Particles with Enhanced Electrocatalytic Activity

Morphology‐ and composition‐controlled synthesis of Au–Pd bimetallic particles was realized by a facile ionic liquid assisted route at room temperature. The morphologies of the synthesized particles, such as nanoflake‐constructed spheres with a core–shell structure, nanoparticle‐constructed spheres, and nanoparticle‐constructed dendrites, could be well controlled by the present route. The ionic liquid was found to play a key role in the formation of these interesting particles. Moreover, the composition (Au:Pd) of the particles could be modulated by means of the molar ratio of the metal precursors in the feeding solutions. The Au–Pd bimetallic particles exhibit high electrocatalytic activity toward oxidation of ethanol and formic acid. Furthermore, cyclic voltammetric studies on the as‐prepared Au–Pd bimetallic particles revealed good electroactivity for H₂O₂, which results in an effective amperometric H₂O₂ sensor.     

Rational Design of Push–Pull Fluorene Dyes: Synthesis and Structure–Photophysics Relationship

Our work surveyed experimental and theoretical investigations to construct highly emissive D –π–A (D=donor, A=acceptor) fluorenes. The synthetic routes were optimised to be concise and gram‐scalable. The molecular design was first rationalised by varying the electron‐withdrawing group from an aldehyde, ketotriazole or succinyl to methylenemalonitrile or benzothiadiazole. The electron‐donating group was next varied from aliphatic or aromatic amines to saturated cyclic amines ranging from aziridine to azepane. Spectroscopic studies correlated with TD‐DFT calculations provided the optimised structures. The selected push–pull dyes exhibited visible absorptions, significant brightness, important solvatofluorochromism, mega‐Stokes shifts (>250 nm) and dramatic shifts in emission to the near‐infrared. The current library includes the comprehensive characterization of 16 prospective dyes for fluorescence applications. Among them, several fluorene derivatives bearing different conjugation anchors were tested for coupling and demonstrated to preserve the photophysical responses once further bound.