Surface plasmon resonance studies on molecularly imprinted films

Novel molecular recognition films were prepared from modified polysulfone having perillaldehyde moiety as a side group. The molecular recognition films were obtained from perillaldehyde polysulfone by adopting 9‐ethyladenine as a print molecule. The molecular recognition phenomena were studied by surface plasmon resonance (SPR) spectroscopy. Adsorption of adenosine (As) and guanosine (Gs) in the molecularly imprinted film was studied. Dual adsorption isotherms were observed for As in 9‐EA imprinted films, while nonspecific adsorption isotherms for Gs in those films. This revealed that the molecular recognition sites toward As were constructed in the films thus prepared. The apparent affinity constant toward As determined by using apparent adsorption isotherms ranged from 7.90 × 10³ to 3.31 × 10⁴ mol^?1 dm³. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Assaying sialyltransferase activity with surface plasmon resonance

Here, we describe an activity assay for sialyltransferases based on surface plasmon resonance (SPR). Different natural and synthetic oligosaccharides serving as acceptor substrates for the sialyltransferase ST3Gal-III (EC 2.4.99.6) were immobilized or synthesized on SPR chips. The chip was then exposed to different concentrations of a reaction mixture of ST3Gal-III and CMP-Neu5Ac either by injection or by external application of the reaction mixture to the chip surface. The binding of two lectins, one that specifically recognizes the unmodified acceptor, the other the sialylated oligosaccharide, was utilized to determine the extent of enzymatic turnover. In order to obtain enzymatic activities, the SPR data were correlated to data obtained from a classical radio assay. After regeneration, that is, cleavage of the sialic acid residues by using a sialidase, the chip is available for new experiments. The technique allows the rapid determination of sialyltransferase activity with only nanomolar quantities of acceptor substrates and should be of particular value in cases in which a large variety of samples, including cell lysates, have to be screened for their enzymatic activities.     

Surface plasmon resonance metal-coupled biomass carbon modified TiO2 nanorods for photoelectrochemical water splitting

Exploring efficient and stable photoanode materials is a necessary link to realize the practical application of solar-driven photoelectrochemical (PEC) water splitting.Hence,we prepared rutile TiO2 nanorods,with a width of 50 nm,which was growth in situ on carbon cloth (TiO2@CC) by hydrothermal reaction.And then,Ag nanoparticles (NPs) and biomass N,S-C NPs were chosen for the additional modification of the fabricated TiO2 nanorods to produce broccoli-like Ag-N,S-C/TiO2@CC nanocomposites.According to the result of ultraviolet-visible diffuse reflectance spectroscopy (UV-vis) and PEC water splitting per-formance tests,Ag-N,S-C/TiO2@CC broadens the absorption region of TiO2@CC from the ultraviolet region to the visible region.Under AM 1.5G solar light irradiation,the photocurrent density of Ag-N,S-C/TiO2@CC is 89.8 μA·cm-2,which is 11.8 times higher than TiO2@CC.Under visible light irradiation,the photocurrent density of Ag-N,S-C/TiO2@CC reaches to 12.6 μA·cm-2,which is 21.0 times higher than TiO2@CC.Moreover,Ag-N,S-C/TiO2@CC shows a photocurrent responses in full pH range.It can be found that Ag NPs and N,S-C NPs play key roles in broaden the absorption range of TiO2 nanorods to the visible light region and,promote the occurrence of PEC water oxidation reaction due to the surface plasmon resonance effect of Ag NPs and the synergistic effect of N,S-C NPs.The mechanism demonstrated that Ag-N,S-C/TiO2@CC can separate the photogenerated electron-hole pairs effectively and transfer the photogenerated electrons to the photocathode (Pt plate) in time.This research provides a new strategy for exploration surface plasma metal coupled biomass carbon materials in the field of PEC water splitting.     

Upconversion luminescence enhancement of NaYF4:Yb3+,Er3+ nanocrystals induced by the surface plasmon resonance of nonstoichiometric WO2.72 semiconductor

Upconversion luminescence of rare‐earth ions doped nanoparticles can be enhanced by the localized surface plasmon resonance (LSPR) of noble metals nanoparticles, which was extensively investigated. The semiconductor nanomaterials such as the WO_2.72 exhibited the tunable LSPR, which provide the possibility for the luminescence enhancement of upconversion nanoparticles. In this work, the urchin‐like WO_2.72 was successfully prepared by solvothermal method, exhibiting the LSPR in the near infrared region. The influence of LSPR of WO_2.72 on the upconversion luminescence of NaYF₄:Yb³⁺,Er³⁺ nanoparticles was investigated firstly. The 525, 542, and 660 nm upconversion luminescence of NaYF₄: Yb³⁺,Er³⁺ nanoparticles was increased by the 10, 8, and 12 factors, respectively, which was from the enhanced excitation field induced by the WO_2.72 film.     

Characterisation of the binding of cationic amphiphilic drugs to phospholipid bilayers using surface plasmon resonance

The interactions of three cationic amphiphilic drugs (CPZ, AMI, PROP) with phospholipid vesicles comprising DOPC, DMPC, or DSPC were investigated using surface plasmon resonance (SPR). Responses for CAD concentrations in the range 15.625 to 1500 microM were measured. The greatest uptake by each phospholipid bilayer occurred with CPZ. Inclusion of CAD concentrations between 750 and 1500 microM provided evidence for a second nonsaturable binding process, which may arise from intercalation of the drugs within the lipid bilayer. CAD binding was additionally shown to be dependent on membrane fluidity. Responses were initially fitted over a concentration range of 15.625 to 500 microM using a model which incorporated terms for a saturable binding site. This yielded very poor values of K(D) and nonsensible values of saturation responses. Subsequently, responses were fit to the expression for a model which incorporated terms for both a saturable binding site and second nonsaturable site. Measurable binding affinities (K(D) values ranged from 170 to 814 microM) were obtained for DOPC and DMPC bilayers which are similar to values reported previously. This work demonstrates that SPR studies with synthetic phospholipid bilayers provide a potentially useful approach for characterising drug-membrane binding interactions and for providing insight into the processes that contribute to drug-membrane binding.     

基于表面等离子体共振效应的Ag(Au)/半导体纳米复合光催化剂的研究进展

由具有表面等离子体共振(surface plasmon resonance,SPR)效应的贵金属(Ag、Au等)纳米粒子和半导体纳米结构组成的纳米复合光催化剂具有优异的可见光光催化活性,成为新型光催化材料的研究热点之一。本文综述了Ag(Au)/半导体纳米复合光催化剂的制备方法、基本性质以及光催化应用方面的一些重要研究进展;重点介绍了Ag(Au)等纳米粒子的表面等离子共振增强可见光催化活性的机理,以及Ag(Au)纳米粒子与不同类型半导体复合的光催化剂的光催化性能,其中所涉及的半导体包括金属氧化物、硫化物和其他一些半导体;本领域未来几年的研究热点将集中于新型高效的Ag(Au)/半导体纳米复合光催化剂的微结构调控及其用于可见光驱动有机反应的机理研究。本文为基于SPR效应构建Ag(Au)/半导体纳米复合光催化剂的研究提供了有力的参考依据,并且指出Ag(Au)/半导体纳米复合光催化剂的研究是发展可见光高效光催化剂的重要方向。     

A new method for measuring wetness of flowing steam based on surface plasmon resonance

Stacked precursors of Cu-Zn-Sn-S were grown by radio frequency sputtering and annealed in a furnace with Se metals to form thin-film solar cell materials of Cu₂ZnSn(S,Se)₄ (CZTSSe). The samples have different absorber layer thickness of 1 to 2 μm and show conversion efficiencies up to 8.06%. Conductive atomic force microscopy and Kelvin probe force microscopy were used to explore the local electrical properties of the surface of CZTSSe thin films. The high-efficiency CZTSSe thin film exhibits significantly positive bending of surface potential around the grain boundaries. Dominant current paths along the grain boundaries are also observed. The surface electrical parameters of potential and current lead to potential solar cell applications using CZTSSe thin films, which may be an alternative choice of Cu(In,Ga)Se₂. PACS number: 08.37.-d; 61.72.Mm; 71.35.-y     

Two-dimensional ultrathin gold film composed of steadily linked dense nanoparticle with surface plasmon resonance

Background

Noble metallic nanoparticles have prominent optical local-field enhancement and light trapping properties in the visible light region resulting from surface plasmon resonances.

Results

We investigate the optical spectral properties and the surface-enhanced Raman spectroscopy of two-dimensional distinctive continuous ultrathin gold nanofilms. Experimental results show that the one- or two-layer nanofilm obviously increases absorbance in PEDOT:PSS and P3HT:PCBM layers and the gold nanofilm acquires high Raman-enhancing capability.

Conclusions

The fabricated novel structure of the continuous ultrathin gold nanofilms possesses high surface plasmon resonance properties and boasts a high surface-enhanced Raman scattering (SERS) enhancement factor, which can be a robust and cost-efficient SERS substrate. Interestingly, owing to the distinctive morphology and high light transmittance, the peculiar nanofilm can be used in multilayer photovoltaic devices to trap light without affecting the physical thickness of solar photovoltaic absorber layers and yielding new options for solar cell design.     

Design of a hairpin polyamide, ZT65B, for targeting the inverted CCAAT box (ICB) site in the multidrug resistant (MDR1) gene

A novel hairpin polyamide, ZT65B, containing a 3-methylpicolinate moiety was designed to target the inverted CCAAT box (ICB) of the human multidrug resistance 1 gene (MDR1) promoter. Binding of nuclear factor-Y (NF-Y) to the ICB site upregulates MDR1 gene expression and is, therefore, a good target for anticancer therapeutic agents. However, it is important to distinguish amongst different promoter ICB sites so that only specific genes will be affected. All ICB sites have the same sequence but they differ in the sequence of the flanking base pairs, which can be exploited in the design of sequence-specific polyamides. To test this hypothesis, ten ICB-containing DNA hairpins were designed with different flanking base pairs; the sequences ICBa and ICBb were similar to the 3'-ICB site of MDR1 (TGGCT). Thermal-denaturation studies showed that ZT65B effectively targeted ICBa and ICBb (DeltaTM=6.5 and 7.0 degrees C) in preference to the other DNA hairpins (<3.5 degrees C), with the exception of ICBc (5.0 degrees C). DNase I-footprinting assays were carried out with the topoisomerase IIalpha-promoter sequence, which contains five ICB sites; of these, ICB1 and ICB5 are similar to the ICB site of MDR1. ZT65B was found to selectively bind ICB1 and ICB5; footprints were not observed with ICB2, ICB3, or ICB4. A strong, positive induced ligand band at 325 nm in CD studies confirmed that ZT65B binds in the DNA minor groove. The selectivity of ZT65B binding to hairpins that contained the MDR1 ICB site compared to one that did not (ICBd) was confirmed by surface-plasmon studies, and equilibrium constants of 5x10(6)-1x10(7) and 4.6x10(5) M-1 were obtained with ICB1, ICB5,and ICB2 respectively. ZT65B and the previously published JH37 (J. A. Henry, et al. Biochemistry 2004, 43, 12 249-12 257) serve as prototypes for the design of novel polyamides. These can be used to specifically target the subset of ubiquitous gene elements known as ICBs, and thereby affect the expression of one or a few proteins.     

Molecular recognition of arginine by supramolecular complexation with calixarene crown ether based on surface plasmon resonance

Arginine plays an important role in cell division and the functioning of the immune system. We describe a novel method by which arginine can be identified using an artificial monolayer based on surface plasmon resonance (SPR). The affinity of arginine binding its recognition molecular was compared to that of lysine. In fabrication of an arginine sensing interface, a calix[4]crown ether monolayer was anchored onto a gold surface and then characterized by Fourier Transform infrared reflection absorption spectroscopy, atomic force microscopy, and cyclic voltammetry. The interaction between arginine and its host compound was investigated by SPR. The calix[4]crown ether was found to assemble as a monolayer on the gold surface. Recognition of calix[4]crown monolayer was assessed by the selective binding of arginine. Modification of the SPR chip with the calix[4]crown monolayer provides a reliable and simple experimental platform for investigation of arginine under aqueous conditions.     

Investigation of interfacial processes at tetraruthenated zinc porphyrin films using electrochemical surface plasmon resonance and electrochemical quartz crystal microbalance

In the present work we describe the investigation of interfacial and superficial processes on tetraruthenated zinc porphyrin (ZnTRP) films immobilized on gold electrode surface. In situ and real time measurements employing electrochemical surface plasmon resonance (ESPR) and electrochemical quartz crystal microbalance (EQCM) have given new insights into the electrochemical oxidation of ferrocyanide and phenolic compounds (acetaminophen, dopamine, and catechol) on ZnTRP modified electrodes. The decrease of diode like behavior in the presence of such phenolic species in contrast with ferrocyanide was clearly assigned to the inclusion of those species in the porphyrin film, creating new conduction pathways connecting the gold electrode surface with the film/solution interface. In fact, there are evidences that they can intercalate in the film (catechol > dopamine > acetaminophen), whereas ferrocyanide is completely excluded. Accordingly, the molecular size may play a fundamental role in such a process.     

表面等离子体共振技术对过氧化氢的检测

表面等离子体激元共振技术是一种通过观察芯片金属薄膜表面厚度变化产生信号的光学技术,具有实时、灵敏度高、免标记等优点,本文通过辣根过氧化物酶的酶催化作用对过氧化氢进行实时快速检测。信号强度与过氧化氢浓度呈线性关系,辣根过氧化物酶共价结合至金膜表面保持了酶的活性。和其它方法相比较,该方法为过氧化氢的检测提供了一种选择。     

Investigations of ultrathin polypyrrole films: Formation and effects of doping/dedoping processes on its optical properties by electrochemical surface plasmon resonance (ESPR)

In the present work an investigation of the effects of the electropolymerization mode on the optical properties associated to the doping/dedoping processes of nanometric films of polypyrrole (PPy) is reported, monitoring in situ and in real time using simultaneously surface plasmon resonance and electrochemical techniques (ESPR). The electropolymerization of pyrrole was performed by potentiostatic, potentiodynamic and galvanostatic methods and the use of the ESPR technique showed that the electropolymerization mode is essential to the stability of polymer and the reversibility of its optical properties during the doping and dedoping processes. Thus, the optical properties of oxidized and reduced film were obtained by nonlinear least square fitting using Fresnel equations for a four-layer system. Then, the values of the real and imaginary parts of the complex dielectric constant for PPy fims were correlated with the polymer doping level. Finally, quartz crystal microbalance measurements were also applied to obtain correlation between doping/dedoping processes and the changes in the real and imaginary parts of the dielectric constant of the polypyrrole film, showing that the doping and dedoping processes in the polypyrrole film can act directly on its optical properties while the ESPR technique can give the same information indirectly.     

Ag/SiO_2复合薄膜的表面等离子体共振吸收研究

用射频磁控溅射法制备了Ag/SiO2复合薄膜,通过改变沉积顺序和退火时间,制备不同形貌的金属颗粒复合薄膜,分析了颗粒形貌对表面等离子体共振吸收特性的影响。结果表明,当SiO2纳米颗粒镶嵌在Ag膜中,同Ag纳米颗粒镶嵌在SiO2中一样,也同样产生明显的表面等离子体共振吸收。     

Tunable surface plasmon resonance frequencies of monodisperse indium tin oxide nanoparticles by controlling composition,size, and morphology

Monodisperse indium tin oxide nanoparticles (ITO NPs) with high crystallinity have been synthesized by the rapid thermal injection method and the seed-mediated growth method. We demonstrate that the surface plasmon resonance (SPR) frequencies of ITO NPs can be manipulated from 1,600 to 1,993 nm in near-infrared band by controlling the composition, size, and morphology. The doping Sn concentration in ITO NPs could be controlled via changing the %Sn in the initial feed from 0% to 30%. The shortest SPR wavelength at 1,600 nm with 10% Sn doping concentration indicates highest free electron carrier concentration in ITO NPs, which has direct relationship with doping Sn⁴⁺ ions. Furthermore, we demonstrate that the SPR peaks can also be tuned by the size of ITO NPs in the case of uniform doping. Besides, compared with the ITO NPs, single crystalline ITO with nanoflower morphology synthesized through the one-pot method exhibit SPR absorption peak features of red-shifting and broadening.     

Spectroelectrochemical phenomena on surface plasmon resonance of Au nanoparticles immobilized on transparent electrode

Different shapes (nanosphere or nanorod) of gold nanoparticles (Au-NPs) were synthesized with and without ultrasonic irradiation in the presence of citric acid. Spherical-shaped and rod-shaped Au-NPs showed different surface plasmon resonance (SPR) absorption bands. The Au-NPs with different shapes were immobilized on a monolayer of 3-aminopropyltriethoxysilane (APS) coated on an indium-tin oxide (ITO) electrode. The potential dependence of the SPR band of different shaped Au-NPs in an aqueous solution was explored. The SPR band and intensity changes of the Au-NPs were found to depend on the applied potential. The spherical-shaped and rod-shaped Au-NPs showed different SPR absorption behaviors when potential was applied. These behavior changes were interpreted as the result of the potential-induced changes of the local dielectric environment around the nanoparticles due to molecular absorption/desorption and the charging/discharging of the particles.     

Surface-plasmon-resonance-based chemical proteomics: efficient specific extraction and semiquantitative identification of cyclic nucleotide-binding proteins from cellular lysates by using a combination of surface plasmon resonance, sequential elution and liquid chromatography-tandem mass spectrometry

Chemical proteomics is a powerful methodology for identifying the cellular targets of small molecules, however, it is biased towards abundant proteins. Therefore, quantitative strategies are needed to distinguish between specific and nonspecific interactions. Here, we explore the potential of the combination of surface plasmon resonance (SPR) coupled to liquid chromatography-tandem mass spectrometry (LC-MS/MS) as an alternative approach in chemical proteomics. We coupled cGMP molecules to the SPR chip, and monitored the binding and dissociation of proteins from a human lysate by using sequential elution steps and SPR. The eluted proteins were subsequently identified by LC-MS/MS. Our approach enabled the efficient and selective extraction of low-abundant cyclic-nucleotide-binding proteins such as cGMP-dependent protein kinase, and a quantitative assessment of the less- and nonspecific competitive binding proteins. The data show that SPR-based chemical proteomics is a promising alternative for the efficient specific extraction and quantitative identification of small-molecule-binding proteins from complex mixtures.