CdS/TiO2复合纳米微粒的原位合成及性质研究

采用一种新方法,在TiO₂表面原位合成CdS纳米微粒,并用红外光谱跟踪了CdS/TiO₂复合纳米微粒的形成过程.紫外吸收光谱研究表明TiO₂对CdS纳米微粒的形成有很好的稳定作用,荧光光谱研究结果表明,这种纳米异质结构有着良好的电荷分离.     

Sensitive biosensing strategy based on functional nanomaterials

The first decade of the 21st century has been labeled as the sensing decade. The functional nanomaterials offer excellent platforms for fabrication of sensitive biosensing devices, including optical and electronic biosensors. A lot of works have fo- cused on the biofunctionalization of different nanomaterials, such as metal nanoparticles, semiconductor nanoparticles and carbon nanostructures, by physical adsorption, electrostatic binding, specific recognition or covalent coupling. These biofunc- tionalized ...     

Ag负载TiO2核壳基底的制备及对结晶紫的高效(SERS)检测

通过简单的一步水热法制备了TiO2核壳微球,然后经过原位光还原将Ag负载于其表面,成功得到了用于有机分子检测的Ag负载TiO2核壳表面增强拉曼散射（SERS）基底。得益于TiO2核壳微球的结构,其对结晶紫（CV）分子表现出高的吸附容量。单一TiO2核壳微球对CV的检测限为10-3 M,而负载Ag以后,其对CV的检测限能达到10-7 M,增强因子（EF）可达3.49×105。优异的SERS检测性能可能归因于以下几点：（1）半导体TiO2为Ag纳米粒子提供了均匀分散的骨架,创造了高密度的热点;（2）为CV分子提供了大的吸附面积;（3）复合材料促进了激发光子的相互作用。     

What is the effective charge of TGA-stabilized CdTe nanocolloids?

The surface charge of semiconductor nanoparticles, Q, is an important parameter which determines their electrokinetic behavior, stability in water and polar solvents, functions of optical and electronic devices, self-assembly properties, and interactions with cell membranes. We have developed a simple method for quantitative determination of Q in their native aqueous environment. The method does not require the knowledge of exact atomic structure or make assumptions about effects of drying on charge distribution. The method is based on titration of nanoparticle dispersion with a solution of oppositely charged polyelectrolyte. The point of complete neutralization is recognized as an inflection point on the dependence of fluorescence intensity on the amount of polyelectrolyte added. Thioglycolic acid-stabilized CdTe nanoparticles 2 nm in diameter were found to carry an average Q from -2.6 to -5.5 for pH 7.5 to 10, respectively. This charge is found to be smaller than that calculated theoretically for an analogous structure (i.e., Q = -8), presumably due to adsorption of Cd(2+) ions on the stabilizer shell and on Te atoms with unsaturated valence located on the side planes of CdTe tetrahedrons.     

Preparation of high-quality organic semiconductor nanoparticle films by solvent-evaporation-induced self-assembly

Organic semiconductor nanoparticles are expected to be used in organic optical and electronic devices due to their unique optical and electrical properties. However, no method has been reported for the preparation of high-quality organic nanoparticle films without remaining additives and being capable of dealing with binary nanoparticle blends. We developed a simple approach to fabricate high-quality organic semiconductor nanoparticle films from their aqueous solutions by solvent-evaporation-induced self-assembly. Only volatile solvents are employed in the nanoparticle solutions, so the self-assembled nanoparticle films are free of additives. Moreover, this method is also suitable for fabricating thin films containing binary nanoparticles. Therefore, it paves the way for potential applications of organic semiconductor nanoparticles in nanoscale optical and electronic devices.     

合成聚丙酰胺-硫属半导体复合纳米材料的新技术

在水溶液体系中采用同步聚合-水解技术（Simultaneous Polymerization-Hydrolysis）制备聚丙烯酰胺-半导体纳米复合材料。该SPH技术是基于丙烯酰胺单体的聚合和MS(M=Cd,Pb,Zn)纳米粒子的形成同步发生,使生成的半导体纳米粒子可均匀分散在聚丙烯酰胺基质中。该技术还为制备其它有机聚合物-金属硫化物纳米复合物提供了一种新途径。     

Concentration of gold nanoparticles in the QCM sensitive film as a factor of adsorption properties controlling

The adsorption properties of sensitive films formed by gold nanoparticles, dropped from solutions with different nanoparticles content are investigated using mass-sensitive (QCM) sensors. The dependence of surface adsorption capacity on nanoparticles concentration is shown. The decrease of surface concentration of nanoparticles leads to the increase of sensors sensitivity to different alcohols and water. The adsorption character of water (response amplitude and kinetics) substantially differs form that of alcohols. The sensitivity of gold nanoparticles layers to water is more then one order higher then to alcohols. The kinetics of water adsorption runs in two stages.     

O-羧甲基壳聚糖纳米微粒制备及对Ni~(2+)吸附研究

将壳聚糖与氯乙酸反应,通过控制反应条件制备了取代度为0.71的O-羧甲基壳聚糖,将改性后的O-羧甲基壳聚糖与多聚磷酸钠反应,制备了粒径分布在370-710nm的O-羧甲基壳聚糖纳米微粒,透射电镜观察表明该微粒呈球状,平均粒径为450nm.在此基础上研究了O-羧甲基壳聚糖纳米微粒对工业电镀镍废水Ni~(2+)吸附性能,考察了溶液pH、Ni~(2+)起始浓度、平衡吸附时间、粒径等因素的影响,结果表明:O-羧甲基壳聚糖微粒最佳吸附条件是Ni~(2+)溶液pH为8.0、Ni~(2+)溶液起始浓度为33.28mg/ml、平衡吸附时间为0.5h、粒径较小的O-羧甲基壳聚糖纳米微粒对Ni~(2+)的吸附量要大于粒径较大的吸附量.     

A spectroscopic and electrochemical approach to the study of the interactions and photoinduced electron transfer between catechol and anatase nanoparticles in aqueous solution

We have combined in situ photoelectrochemical and spectroscopic techniques (Attenuated Total Reflection Infrared, ATR-IR, and Resonance Raman Spectroscopy) for the study of the charge-transfer complex formed upon adsorption of catechol on anatase nanoparticles in contact with aqueous acidic solutions. Vibrational spectroscopies reveal the existence of at least two adsorbate configurations: catecholate in a chelate configuration and molecularly adsorbed catechol, with apparent values of -12.3 and -10.5 kJ mol(-1), respectively. These values are significantly less negative than the values reported for anatase colloidal dispersions. The adsorption of both catechol species on the nanoparticulate anatase thin films follows the Freundlich isotherm. As revealed by resonance Raman spectroscopy, only the adsorbed chelating catecholate forms the charge-transfer complex. The electron transfer from the adsorbate to the anatase nanoparticles has been evidenced by the development of a negative photopotential upon 514.5 or 632.8 nm laser illumination of an anatase nanostructured thin film electrode in contact with a catechol solution. The time evolution of the Raman spectra shows an increasing fluorescence indicating that, upon electron injection, catechol polymerization occurs on the TiO2 surfaces. This conclusion is confirmed by in situ ATR-IR measurements, which show a progressive broadening of the catecholate bands together with the appearance of new signals. This study illustrates the benefits of combining electrochemical, infrared, and Raman techniques for the elucidation of processes occurring at the semiconductor/solution interface. Finally, evidence is given on the different adsorption and reactivity behavior found for suspensions and nanoporous thin films under equivalent experimental conditions.     

Promising avenues of research in nanoscience: chemistry of semiconductor nanoparticles

The state-of-the-art in the field of research on semiconductor nanoparticles is analyzed; cadmium chalcogenide nanoparticles are considered in most detail. Emphasis is placed on the methods of synthesis and on control of the size, composition, and structure of semiconductor nanoparticles — “quantum dots”. The state of the surface plays a significant role in determining the properties of nanoparticles. Organized nanostructures comprised of quantum dots are considered. The properties of semiconductor nanoparticles are described. Prospects for applications of semiconductor nanomaterials are discussed. Dedicated to Academician V. I. Minkin on the occasion of his 70th birthday. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 811–836, April, 2005.     

Reflection of light by metal nanoparticles at electrodes

We present model calculations for the reflection spectrum of an ordered two dimensional array of metallic nanoparticles located near an electrochemical interface. We consider three cases, nanoparticles at: (i) a metal electrode, (ii) a transparent semiconductor electrode, and (iii) an electrified liquid/liquid interface. In the case of a metal electrode, the presence of nanoparticles introduces dips in reflection, whose position and depth are affected by the distance and size of the nanoparticles. For both a transparent semiconductor electrode and a liquid/liquid interface, the presence of nanoparticles enhances reflectivity. The spectra are sensitive to the particle spacing and size. The response from all three systems exhibits a strong dependence on the polarisation of light. The dependence on the angle of incidence reveals shallow dips typical of surface plasmon resonance spectra. These findings suggest diagnostic tools for the detection and characterisation of nanoparticle monolayers on functionalised electrodes, and enable electrovariable optical devices based on the controlled assembly of nanoparticles at interfaces.     

Analysis of plasma protein adsorption onto PEGylated nanoparticles by complementary methods: 2-DE, CE and Protein Lab-on-chip system

The biodistribution of colloidal carriers after their administration in vivo depends on the adsorption of some plasma proteins and apolipoproteins on their surface. Poly(methoxypolyethyleneglycol cyanoacrylate-co-hexadecylcyanoacrylate) (PEG-PHDCA) nanoparticles have demonstrated their capacity to cross the blood-brain barrier (BBB) by a mechanism of endocytosis. In order to clarify this mechanism at the molecular level, proteins and especially apolipoproteins adsorbed at the surface of PEG-PHDCA nanoparticles were analyzed by complementary methods such as CE and Protein Lab-on-chip in comparison with 2-D PAGE as a method of reference. Thus, the ability of those methodologies to identify and quantify human and rat plasma protein adsorption onto PEG-PHDCA nanoparticles and conventional PHDCA nanoparticles was evaluated. The lower adsorption of proteins onto PEG-PHDCA nanoparticles comparatively to PHDCA nanoparticles was evidenced by 2-D PAGE and Protein Lab-on-chip methods. CE allowed the quantification of adsorbed proteins without the requirement of a desorption procedure but failed, in this context, to analyze complex mixtures of proteins. The Protein Lab-on-chip method appeared to be very useful to follow the kinetic of protein adsorption from serum onto nanoparticles; it was complementary to 2-D PAGE which allowed the identification (with a relative quantification) of the adsorbed proteins. The overall results suggest the implication of the apolipoprotein E in the mechanism of passage of PEG-PHDCA nanoparticles through the BBB.     

Stimuli responsive release of metalic nanoparticles on semiconductor substrates

Optically active metal nanoparticles have been of recent and broad interest for applications to biomarker detection because of their ability to enable high sensitivity enhancements in various optical detection techniques. Here, we report stimuli responsive release of metallic nanoparticles on a semiconductor thin film array structure based on pH change. The metallic nanoparticles are obtained by a simple redox procedure on the semiconductor surface. This approach allows controlling nanoparticle surface coatings in situ for biomolecule conjugation, such as DNA probes on nanoparticles, and rapid stimuli responsive release of these nanoparticles upon pH change.     

Size control and catalytic activity of highly dispersed Pd nanoparticles supported on porous glass beads

This paper presents a novel in situ method to prepare monodispersed palladium nanoparticles supported on porous glass beads with an egg-shell structure at room temperature. This method integrates two processes of ion exchange and reduction in one step just by changing the solvent from water to alcohol. The monodispersed Pd nanoparticles around 3.75 nm in diameter with a face-centered cubic structure have been successfully prepared. The adsorption capacity for palladium reached 55.00 ± 0.55 mg/g in ethanol, which was 26 times larger than that in water. These Pd nanoparticles supported on porous glass beads showed an excellent catalytic performance through the hydrogenation of cyclohexene. In addition, this in situ method was also successfully applied to prepare monodispersed silver and gold nanoparticles supported on porous glass beads. Overall, this facile method provided an alternative for preparing a supported nanoparticle catalyst in a green way.     

Continuous tuning of cadmium sulfide and zinc sulfide nanoparticle size in a water-in-supercritical carbon dioxide microemulsion

The size and size dispersion of cadmium sulfide and zinc sulfide semiconductor nanoparticles can be continuously tuned over a wide range of values by adjusting the density of the fluid phase in water-in-supercritical CO2 microemulsions. The average size of the ZnS nanoparticles decreases linearly from approximately 9.1 to 1.9 nm with increasing fluid density from 0.86 to 0.99 g cm(-3) at a water-to-surfactant ratio (W value) of 10. At a W value of 6, the particle size can be tuned from 7.0 to 1.5 nm in the same density range. In the case of CdS nanocrystals, the size varied from 7.1 to 2.0 nm when the W value was 10 and from 4.0 to 1.3 nm when the W value employed was 6, in the same density range. Monodispersive CdS and ZnS nanoparticles were synthesized by chemical reaction of cadmium or zinc nitrate with sodium sulfide, using two water-in-supercritical CO2 microemulsions as nanoreactors followed by protection with a fluorinated-thiol stabilizer. The stabilizer is introduced at 6 and 16 minutes after the mixing of the two microemulsions where the intensity of the characteristic absorption peak due to the quantum confinement properties of the CdS and ZnS nanoparticles (280 and 360 nm) reaches a maximum, respectively. The supercritical CO2 microemulsion method represents a simple approach to use a density-tunable solvent for synthesizing size-controlled semiconductor nanoparticles over a broad range of values.     

Luminescent polymer microcapsules addressable by a magnetic field

The simultaneous encapsulation of both luminescent semiconductor and magnetic oxide nanoparticles in polymer microcapsules is demonstrated for the first time. Highly luminescent CdTe semiconductor nanocrystals serve as luminescent markers, while magnetic Fe3O4 nanoparticles allow external manipulation of the capsules by magnetic field. The method introduced is general enough to allow the fabrication of different types of multifunctional capsules in a similar way. The use of multifunctional water-compatible capsules introduced in this paper for the controlled release and directed drug delivery in biological systems is envisaged.     

Formation of monodispersed PVP-capped ZnS and CdS nanocrystals under microwave irradiation

Poly (N-vinyl-2-pyrrolidone) (PVP)-capped ZnS, CdS nanoparticles were prepared by a microwave method from Zn(Ac)₂ or Cd(Ac)₂ and thiourea in N,N-dimethylformamide (DMF) solution. The reaction process was monitored by the temporal evolution of the absorption spectrum. With PVP as stabilizer, monodispersed semiconductor nanoparticles, which showed high quantum size effect, have been obtained. Further study showed that the microwave irradiation could influence selectively the nucleation and growing rates of different semiconductor nanoparticles.     

AgSbS2 semiconductor-sensitized solar cells

We present a ternary semiconductor nanoparticle sensitizer – AgSbS₂ – for solar cells. AgSbS₂ nanoparticles were grown using a two-stage successive ionic layer adsorption and reaction process. First, Ag₂S nanoparticles were grown on the surface of a nanoporous TiO₂ electrode. Secondly, a Sb–S film was coated on top of the Ag₂S. The double-layered structure was transformed into AgSbS₂ nanoparticles ~ 40 nm in diameter, after post-deposition heating at 350 °C. The AgSbS₂-sensitized TiO₂ electrodes were fabricated into liquid-junction solar cells. The best cell yielded a power conversion efficiency of 0.34% at 1 sun and 0.42% at 0.1 sun. The external quantum efficiency (EQE) spectrum covered the range of 380–680 nm with a maximal EQE of 10.5% at λ = 470 nm. The method can be applied to grow other systems of ternary semiconductor nanoparticles for solar absorbers.     

Efficient and selective separation of metronidazole from human serum by using molecularly imprinted magnetic nanoparticles

Magnetic molecularly imprinted nanoparticles were prepared through surface‐initiated reversible addition fragmentation chain transfer polymerization by using metronidazole as a template. The molecularly imprinted magnetic nanoparticles were characterized by attenuated total reflection Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, transmission electron microscopy, X‐ray diffraction, and vibrating sample magnetometry. The adsorption characteristics were also investigated and the kinetics of the adsorption of metronidazole on the imprinted nanoparticles were described by the second‐order kinetic model with the short equilibrium adsorption time (30 min). The adsorption isotherm was well matched with the Langmuir isotherm in which the maximum adsorption capacity was calculated to be 40.1 mg/g. Furthermore, the imprinted magnetic nanoparticles showed good selectivity as well as reusability even after six adsorption–desorption cycles. The imprinted magnetic nanoparticles were used as a sorbent for the selective separation of metronidazole from human serum. The recoveries of metronidazole from human serum changed between 97.5 and 99.8% and showed similar sensitivity as an enzyme‐linked immunoassay method. Therefore, the molecularly imprinted magnetic nanoparticles might have potential application for the selective and reliable separation of metronidazole from biological fluids in clinical applications.     

Influence of Light Scattering by Residual Alumina Nanoparticles on the Analysis of Surfactants Adsorption Using Spectroscopy

The adsorption of a surfactant mixture, based on an anionic surfactant, sodium dodecyl benzenesulfonate (SDBS) and a nonionic surfactant (Triton X-100, or TX100), on alumina nanoparticles was determined by solution depletion method combined with spectrometric measurement. It is shown that the light scattering, originated from the residual adsorbent alumina particles in the supernatant after centrifugation separation, interferes with the measurements of absorbance of the surfactant molecules, and therefore constitutes an error source for determination of the surfactant concentration in the supernatant by spectrometric means. The intensity of this light scattering, namely the influence of the residual alumina nanoparticles upon the surfactant adsorption, was related to the surfactant adsorption and its equilibrium concentration and varied among a batch. In this paper we report a Kalman filter method in order to eliminate the variational scattering background caused by non-separated residual alumina nanoparticles in each supernatant. This method is of interest as it is simple, easy to carry out and of high precision.