LDHs薄膜基纳米荧光传感器的制备及其研究进展

层状复合氢氧化物(LDHs)是一种层板金属元素和层间离子可调的无机层状材料,利用其独特的插层组装特性,基于静电、氢键、范德华力等相互作用力,功能性荧光客体分子可与LDHs纳米片复合构筑多功能荧光薄膜材料.LDHs薄膜基荧光材料用于荧光传感器,在有机挥发性气体(VOCs)、温度、压力、重要生物分子等的检测中显示了良好性能.本文总结了LDHs复合薄膜的制备方法以及近年来其在纳米荧光传感领域的进展,并对其未来发展做出了展望.     

用于低浓度三聚氰胺选择性检测的铝/银纳米传感器的组装及其SERS性能

通过置换法在铝板上快速制备了一种即插即用型的Al/Ag纳米表面增强拉曼光谱(SERS)活性基底。结果表明该SERS基底较好地解决了银纳米颗粒在支撑物质上的吸附问题,能够快速实现对三聚氰胺的检测,而且具有操作简单、成本低、无损伤检测等优点,最低检测浓度能达到10^-7 mol·L^-1,满足国家食品安全要求的最低标准。另外,Al/Ag活性基底对三聚氰胺检测具有较高的拉曼测试重现性,连续测定15 h的过程中拉曼强度波动不大;且该Al/Ag活性基底能够在三乙醇胺、N,N-二甲基甲酰胺和1,2-丙二胺等胺类物质中实现对三聚氰胺的选择性检测。     

A novel enzyme-mimic nanosensor based on quantum dot-Au nanoparticle@silica mesoporous microsphere for the detection of glucose

QD-Au NP@silica mesoporous microspheres have been fabricated as a novel enzyme-mimic nanosensor. CdTe quantum dots (QDs) were loaded into the core, and Au nanoparticles (NPs) were encapsulated in the outer mesoporous shell. QDs and Au NPs were separated in the different space of the nanosensor, which prevent the potential energy or electron transfer process between QDs and Au NPs. As biomimetic catalyst, Au NPs in the mesoporous silica shell can catalytically oxidize glucose as glucose oxidase (GOx)-mimicking. The resultant hydrogen peroxide can quench the photoluminescence (PL) signal of QDs in the microsphere core. Therefore the nanosensor based on the decrease of the PL intensity of QDs was established for the glucose detection. The linear range for glucose was in the range of 5–200 μM with a detection limit (3σ) of 1.32 μM.     

氮掺杂发光碳纳米点的研究探索

采用微波法制备了氮掺杂碳纳米点。通过调控碳纳米点中氮元素的掺杂含量和表面的化学环境,实现了对碳纳米点发光特性的调控。在此基础上,可实现完全基于氮掺杂碳纳米点的荧光墨水、比率型荧光探针及光泵浦激光。研究目的在于探索氮掺杂碳纳米点的发光机理,揭示影响碳纳米点荧光量子效率的因素及其在生物成像、传感、防伪、信息存储、激光等领域的应用。     

Determination of poorly fluorescent carbamate pesticides in water, bendiocarb and promecarb, using cyclodextrin nanocavities and related media

The effect of native cyclodextrins (alpha, beta, or gammaCD with six, seven and eight glucose units, respectively), hydroxypropyl-beta-cyclodextrin (HPCD), chitosan (CHT) and glucose in water solution or water with n-propylamine (PA) as co-solvent upon the UV-vis and fluorescence properties of poorly fluorescent N-methyl carbamates pesticides (C) as bendiocarb (2,2-dimethyl-1,3-benzodioxol-4-ol methylcarbamate, BC) and promecarb (3-methyl-5-(1-methylethyl)phenol methylcarbame, PC) was examined. Fluorescent enhancement was found for both substrates with all CDs in water or PA-water except from PC with alphaCD. The addition of CHT increases the fluorescence of BC but decreases the fluorescence of PC, and glucose addition gives in both cases no spectral changes. Host-guest interaction was clearly determined by fluorescence enhancement with betaCD and HPCD with a 1:1 stoichiometry for the complexes (C:CD). The values obtained for the association constants (K(A), M(-1)) were (6+/-2)x10(2) and (2.3+/-0.3)x10(2) for BC:betaCD and BC:HPCD complexes, respectively. For PC:betaCD and PC:HPCD the values of K(A) were (19+/-2)x10(2) and (21+/-2)x10(2), respectively. The ratio of the fluorescence quantum yields for the bound and free substrates (phi(CCD)/phi(C)) was in the range 1.74-3.8. The limits of detection (L(D), microg mL(-1)) for the best conditions were (0.57+/-0.02) for BC with HPCD and (0.091+/-0.002) for PC with betaCD in water. Application to the analysis in pesticide spiked samples of tap water and fruit yields satisfactory apparent recoveries (84-114%), and for the extraction procedure in fruits and a commercial formulation, recoveries were of 81-98% and 104%, respectively. The method is rapid, simple, direct, sensitive and useful for pesticide analysis.     

Development of Nanosensors and Bioprobes

We describe the development and application of nanosensors having bioreceptor probes for bioanalysis. The nanoprobes were fabricated with optical fibers pulled down to tips having distal end sizes of approximately 30–60nm. The use of two different types of receptors was investigated. Fiberoptic nanoprobes were covalently bound either with bioreceptors, such as antibodies, or with other receptors, such as cyclodextrins that are selective for the size and chemical structure of the analyte molecules. Theoretical calculations were performed to model the binding of beta-cyclodextrin with pyrene and 5,6-benzoquinoline, and to illustrate the possibility of comparing experimental data with theoretical data. The antibody-based nanoprobe was used for in situ measurements of benzopyrene tetrol in single cells. The performance of the nanosensor is illustrated by intracellular measurements performed on a rat liver epithelial cell line (Clone 9) used as the model cell system. The usefulness and potential of these nanotechnology-based biosensors in biological research and applications are discussed.     

pH荧光纳米传感器的研制及表征

利用溶胶-凝胶技术制得了单分散性很好的二氧化硅纳米微球,通过共价偶联方式引入对pH变化敏感的荧光素异硫氰酸酯（FITC）,这种FITC功能化二氧化硅纳米微球（FITC功能化硅微球）可作为pH荧光纳米传感器。当pH值从4.0变至7.5时,荧光强度增大约30倍。该传感器灵敏度高,响应速度快,容易制备,光稳定性好,可望用于单细胞的pH分析。     

The Hofmeister Anion Effect on Ionophore‐based Ion‐selective Nanospheres Containing Solvatochromic Dyes

Recently reported ionophore‐based ion‐selective nanospheres contained pH‐independent and positively charged solvatochromic dyes. Here, we evaluate systematically the effect of anions to the fluorescence response of the nanospheres. The anion interference was found significant for anion concentrations above 10 mM. The sensor responses in the presence of various anion background was studied. While target ion (K⁺) causes the fluorescence of the nanospheres to decrease, increasing anion background also leads to lower fluorescence intensity. Lipophilic anions such as ClO₄^?, SCN^?, and I^? exhibited much more interference than hydrophilic anions (e. g., NO₃^?, Cl^?, F^?, SO₄^2?). The trend of the anion interference followed the Hofmeister series. A theoretical model was also demonstrated based on anion adsorption on the surface of the nanospheres.     

A joint QM/MD study on α-, β- and γ-cyclodextrins in selective complexation with cathinone

In this article, density functional theory (DFT) calculations and 30 ns molecular dynamic (MD) simulations were performed to investigate the ability of α-, β- and γ-cyclodextrins (CDs) to form selective complexes with cathinone. DFT calculations in the gas phase, water, chloroform and methanol reveal that the solvents, reduce the stability of the complexes. Optimized structures confirm that α-CD cannot encapsulate cathinone, completely, while other CDs showed an opposite behavior. DFT calculations indicate that cathinone has the most stable complex with γ-CD in comparison to the α- and β-CDs. Natural bond orbital and quantum theory of atoms in molecules analyses reveal that the electrostatic interactions between cathinone and CDs are the driving force of the complex formation. MD simulations confirm that different solvents play an important role in the stability of the cathinone complexes and the obtained MD results are in good agreement with the DFT calculations.     

Design and preparation of imprinted surface plasmon resonance (SPR) nanosensor for detection of Zn(II) ions

A novel Zn(II) ions imprinted poly (2-hydroxyethyl Methacrylate-N-methacryloyl-(L)-histidine methyl ester) poly(HEMAH) surface plasmon resonance (SPR) nanosensor were designed for detection of Zn(II) ions in aqueous solution and artificial plasma providing a low cost, rapid and reliable results compared to other techniques such as atomic absorption spectroscopy, inductively coupled plasma-mass spectrometer, X-ray fluorescence with synchrotron radiation. Zn(II) ions imprinted nanofilm on the SPR chip surface was synthesized by bulk polymerization. Characterization of Zn(II) ions imprinted nanosensor was performed by contact angle measurement, atomic force microscopy (AFM), ellipsometry and Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR). Designed nanosensor was applied for selective detection of Zn(II) ions in aqueous solution within the range of 0.5–1.0?µg/mL. The limit of detection (LOD) and limit of quantification (LOQ) were calculated as 0.19 and 0.64?ng/mL, respectively. Association kinetics analysis, Scatchard, Langmuir, Freundlich, Langmuir–Freundlich, Tempkin and Dubinin-Radushkevich isotherms were analyzed to the experimental data in order to identify the adsorption behavior. The selectivity of the SPR nanosensor was examined by using competitive metal ions such as Cd(II), Cu(II), Pb(II), and Fe(II). To evaluate the imprinting effect of Zn(II) ions imprinted (MIP) and non-imprinted (NIP) nanosensor was also prepared as the control. Repeatability of the response signal was tested by four times adsorption–desorption–regeneration cycle.