纳米铂颗粒在酶生物传感器中的应用研究

采用硼氢化钠作为还原剂制备纳米铂颗粒,并分别用羧甲基纤维素(CMC)、羟丙基纤维素(HPC)、聚丙烯酸(PAA)为保护剂,提高纳米铂溶胶的稳定性。将制备的纳米铂颗粒与聚乙烯醇缩丁醛构成复合固酶膜基质,用溶胶-凝胶法固定葡萄糖氧化酶,构建葡萄糖生物传感器。实验表明,纳米铂颗粒可以大幅度提高固定化酶的催化活性。在葡萄糖浓度为10mmol／L的溶液中,响应电流从318nA／cm^2提高到13657nA／cm^2。探讨纳米颗粒效应在固定化酶中所起的作用,并分析不同条件对酶电极响应灵敏度的影响。     

Conductometric biosensor based on glucose oxidase and beta-galactosidase for specific lactose determination in milk

This paper investigates the development of a biosensor associating two distinct enzymatic activities, that of the beta-galactosidase and that of the glucose oxidase, in order to apply it for the quantitative detection of lactose in milk. To eliminate interferences with glucose, a differential mode of measurement was used. Results show a linear calibration curve for lactose concentration between 60 and 800 μM (0.03 to 0.3 g/L). Tests with real commercial milk samples were carried out to validate the conductometric biosensor.     

Fabrication of silica/platinum core-shell particles by electroless metal plating

An electroless metal plating method was used to form Pt shells on sub-micrometer-sized silica (SiO₂) particles fabricated by a sol-gel method. The electroless metal plating method was comprised of three steps: (1) surface-modification of SiO₂ particles with polyvinylpyrrolidone (PVP) (SiO₂/PVP) or poly-diallyldimethylammonium chloride (PDADMAC) (SiO₂/PDADMAC), (2) pre-deposition of Pt nuclei or Pt fine particles on the SiO₂ particles by reducing Pt ions in the presence of SiO₂/PVP particles (SiO₂/PVP-Pt) or SiO₂/PDADMAC particles (SiO₂/PDADMAC-Pt), and (3) growth of the pre-deposited Pt by immersing the SiO₂/PVP-Pt or SiO₂/PDADMAC-Pt particles in a Pt-plating solution. The pre-deposition of Pt nanoparticles was successfully performed for the surface-modified SiO₂ particles since the surface modification possibly strengthened the affinity between the SiO₂ particle surfaces and Pt ions. The Pt nanoparticles were pre-deposited more uniformly in the case of PVP because the pre-deposition took place more slowly for the PVP, which provided uniform surface-modification followed by the uniform pre-deposition of Pt nanoparticles. The formation of Pt shells was successfully performed on the SiO₂/PVP-Pt particles in the electroless metal plating process because Pt nuclei were generated by the reduction of H₂PtCl₆ and then further deposited on the Pt particle surfaces on the SiO₂/PVP-Pt particles.     

Growth of anisotropic platinum nanostructures catalyzed by gold seed nanoparticles

This paper reports an effective method for the synthesis of platinum nanostructures with anisotropic morphologies by decomposition of platinum dichloride in oleylamine at intermediate temperatures catalyzed by gold seed nanoparticles. A small quantity of spherical gold nanoparticles formed in situ was used to trigger the nucleation and anisotropic growth of the Pt nanocrystals. By varying the amount of gold seed nanoparticles, porous flower-like, irregular polyhedron-shaped, multi-branched rod shaped, and caterpillar-like Pt nanostructures were produced in high yields at 190–240 °C in reaction times of a few minutes. Control of morphology under different conditions has been systematically studied and a kinetically controlled induced growth mechanism has been proposed. Electronic Supplementary Material  Supplementary material is available for this article at and is accessible for authorized users. This article is published with open access at Springerlink.com     

Cell membrane disruption induced by amorphous silica nanoparticles in erythrocytes,lymphocytes, malignant melanocytes,and macrophages

It is of critical importance to examine carefully the potential adverse effects of engineered nanoparticles (NPs) on human health and environments. In the present study, we have investigated the disruption of cell membranes induced by amorphous silica NPs in erythrocytes, lymphocytes (Jurkat), malignant melanocytes (B16F10), and macrophages (J774.1); these four types of mammalian cells have distinctive characteristics in terms of nucleated/non-nucleated cells, adherent/non-adherent cells, endocytosis, and phagocytosis. The silica-induced membranolysis was examined by exposing these different cells to serum-free culture media containing the amorphous silica NPs of different diameters (28, 50, 55, 156, and 461 nm) under similar conditions. We investigated how the silica-induced membranolysis of the cells of different origins is influenced by the size and dose of the silica NPs. Additionally, the interaction forces of a silica microsphere with a living cell or a giant unilamellar vesicle composed of zwitterionic phosphatidylcholine lipids were measured by colloid-probe atomic force microcopy, whereby the affinities of silica surface for plasma membranes and protein-free phospholipid membranes were estimated. Possible mechanism of the silica-induced membranolysis was discussed.     

Fabrication and characterization of platinum black and mesoporous platinum electrodes for in-vivo and continuously monitoring electrochemical sensor applications

Most electrochemical biosensors are disposable due to enzymes that are living creatures. Thus, these are limited to use in in-vivo and continuously monitoring biosensor system applications. The mesoporous (pores with a size of 2-50 nm) platinum (Pt) structure formed on a rod-shaped Pt microelectrode was reported for developments glucose sensors without any enzymes. In this paper, plane Pt electrode (non-treated), Pt black electrode, and mesoporous Pt electrode are fabricated and characterized on a silicon substrate in order to check their usability as enzymeless sensing electrodes for in-vivo and continuously monitoring electrochemical biosensors integrated with silicon CMOS read-out circuitry. The Pt black electrode with rough surface was fabricated by using an electrodeposition technique with hexachloroplatinic acid hydrate (HCPA) solutions. The proposed mesoporous Pt electrode with approximately 3 nm in pore diameter was fabricated by using an electrodeposition technique with nonionic surfactant octaethylene glycol monohexadecyl ether (C₁₆EO₈) and HCPA. The measured current responses at 40 mM glucose solution of the fabricated plane Pt, Pt black, and mesoporous Pt electrodes are approximately 12.4 nA/mm², 2.1 μA/mm², and 2.8 μA/mm², respectively. These data indicate that the mesoporous Pt electrode is much more sensitive than the other Pt electrodes and has strong potential for enzymeless electrochemical sensor applications.     

Effect of exposure temperature on the cell membrane disruption induced by amorphous silica nanoparticles in erythrocytes,lymphocytes, and malignant melanocytes

It is of great significance to examine carefully the potentially harmful effects of silica-based nanoparticles (NPs) on human body. In the present study, we have investigated the impact of exposure temperatures (4 °C, 15 °C, 26 °C, and 37 °C) on the cell membrane disruption induced by amorphous silica NPs of different primary diameters (28, 55, 88, 156, and 461 nm) in three different types of cells (erythrocytes, Jurkat, and B16F10), where the serum-free culture media were employed for exposure of the cells to the silica NPs. The size- and dose-dependent membranolytic activity of the silica NPs in each cell type at every temperature appeared to be given by a master curve as a function of the NP surface area per suspension volume, regardless of the NP diameter. This silica-induced membranolysis was significantly enhanced by the higher-temperature exposure of each cell type to the silica NPs. Such effects of exposure temperature on the silica-induced membranolysis in non-adherent cells of RBC and Jurkat were quite similar to each other, regardless of their difference in the presence/absence of nucleus and endocytic ability, whereas that for adherent cells of B16F10 was more remarkable. The filterability of erythrocytes also was measured at different temperatures, whereby the effect of temperature on the deformability of cell membranes was estimated. A possible mechanism underlying the effect of exposure temperature on the silica-induced membranolysis was proposed.     

Multifunctional iron and iron oxide nanoparticles in silica

Iron and iron oxide nanoparticles in silica layers deposited by sol–gel techniques on Si wafers were formed and studied. It was shown that multifunctional nanoparticles of different iron oxides possessing various physical properties can be fabricated by means of post-growth annealing of (SiO₂:Fe)/SiO₂/Si samples in various atmospheres. The hematite, maghemite, and iron nanoparticles were found to be dominant upon annealing the samples in air, argon, and hydrogen atmosphere, respectively. The physical properties of produced hybrid structures were studied by Raman and FT-IR spectroscopy, spectroscopic ellipsometry, AFM, and magnetic measurements. The sol–gel technique with subsequent annealing procedure is demonstrated to be an effective method for the formation of multifunctional hybrid structures composed of iron or iron oxide nanoparticles in silica matrix.     

Quantification and characterization of C-S-H in silica nanoparticles incorporated cementitious system

This paper presents the quantification and nanomechanical properties of calcium silicate hydrate (C-S-H), formed at early stage hydration of tricalcium silicate (major cement phase) in presence of silica nanoparticles (SNPs). SNPs showed dominant nucleation effect at 8 h and pozzolanic effect at 24 h and accelerate the hydration rate (∼83% at 8 h and ∼51% at 24 h) due to the formation of additional C-S-H nuclei. Further, ²⁹Si-NMR and FTIR techniques showed the acceleration in polymerization of silicate chain leading to the formation of tobermorite like structure. Formation of polymerized and crystalline C-S-H gel in presence of SNPs increases the percentage of high density C-S-H (∼40%) and lowers the low density C-S-H (∼52%) at 24 h of hydration, as observed in nanoindentation results.     

The effect of silica nanoparticles on the dustiness of industrial powders

Industrial powders are prompt to be airborne during processing. High dustiness levels may cause process complications like cross-contamination, product loss and filter clogging while increasing the risk of inhalation, dust explosion and fire. Thus, dustiness is often associated with occupational exposure. Despite this, powder products are usually composed of multiple ingredients with silica nanoparticles (S-NP) systematically added to ease their handling. Surprisingly, the relationship between dustiness and product formulation has not been commonly studied. This work investigates the influence of S-NP, SIPERNAT D10 (SD10), on the dustiness of four industrial powders–Avicel PH102, wheat flour, joint filler, and glass beads–using two standard methods: the rotating drum (EN 15051–2) and the vortex shaker (EN 17199–5). Our results show that the dustiness of mixtures powder + SD10 are statistically higher than those of the powder alone and can reach the levels of SD10. TEM micrographs from airborne particles collected in the vortex shaker showed that SD10 detached from the surface of the powder during aerosolisation, emitting nanometric dust; adding SD10 increases the potential for inhalation exposure during industrial processing and handling. Surface energy analysis by inverse gas chromatography (IGC) leads us to conclude that stronger powder-to-SD10 interactions result in less dust emission.     

金属与非金属纳米颗粒增强葡萄糖生物传感器

为了提高葡萄糖传感器的灵敏度和抗干扰性,利用纳米增强效应,以Au、Ag、Pt、SiO2纳米颗粒及金属-无机复合纳米颗粒与聚乙烯醇缩丁醛(PVB)构成复合固定酶膜基质,采用溶胶-凝胶法固定葡萄糖氧化酶(GOD),组成葡萄糖生物传感器.研究表明,纳米颗粒可以大幅度地提高固定化酶的催化活性,增加电极的电流响应灵敏度,改进生物传感器的抗干扰性能,使信噪比提高了32倍.     

Reagentless biosensor based on glucose oxidase wired by the mediator freely diffusing in enzyme containing membrane

Wiring glucose oxidase in the membrane with an immobilized mediator is possible due to the diffusion ability of the latter, if the enzyme containing membrane is formed according to the proposed protocol, including exposing proteins to water-organic mixtures with the high content of organic solvent. In the course of the study, the new glucose oxidase mediator, unsubstituted phenothiazine, was discovered. The diffusion coefficient of the mediator in the resulting membrane is independent of the presence of enzyme. The cyclic voltammograms of the enzyme electrode after appearance of the only glucose in solution obtain a well-defined catalytic shape, which is normally observed for both the enzyme and the mediator in solution. Analytical performances of the resulting biosensor are comparable to the advanced second generation ones, which, however, require covalent linking of the mediator either to the membrane forming polymer or to the enzyme. Even without such covalent linking, the reported biosensor is characterized by an appropriate long-term operational stability allowing reagentless sensing.     

Application of fractional factorial design for green synthesis of cyano-modified silica nanoparticles: Chemometrics and multifarious response optimization

Cyano-functionalized spherical silica nanoparticles (SNPs) were synthesized via Stöber method. A 2?^k-p_IV–fractional factorial design (2^k-p_IV–FFD) was used to smartly prepare monodispersed evenly distributed SNPs. Six factors were considered; concentrations of tetraethylorthosilicate (TEOS), 3-Cyanopropyltriethoxysilane (CPTS), water, and ammonia, reaction time (RT) and stirring time (ST). Two responses; particle size (PS, measured by SEM) and particle-size distribution (PSD, calculated as standard deviation, ±SD) were measured. Control charts were used to decide on impacts of linear and two-way interactions on both responses. Derringer’s function was used to consolidate these multifarious responses into a uniform execution characteristic. Both screening and optimization were always accompanied by ANOVA testing at a 95.0% confidence interval (CI). The ideal synthetic conditions were obtained from the composite desirability plots. Cyano-functionalized SNPs with an average PS of 474.04?±?86.71?nm were produced. Raman spectroscopy and FTIR were used to confirm the functionalization process. Thermogravimetric analysis (TGA) was used to evaluate the thermal behavior of synthesized particles.     

Enhancing the grafting of poly(2-hydroxyethyl methacrylate) on silica nanoparticles (SiO2-g-PHEMA) by the sequential UV-induced graft polymerization with a multiple-UV irradiation

Grafting of poly(2-hydroxyethyl methacrylate) on silica nanoparticles was accomplished via the sequential UV-induced graft polymerization. Under UV-irradiation, the silica was functionalized with the surface initiator, benzophenone (BP) and subsequently graft-polymerized with 2-hydroxyethyl methacrylate (HEMA). The grafting on the silica particles was confirmed by DSC analysis which revealed a shift of the glass transition temperature (T_g) of grafted PHEMA to higher temperature than T_g of ungrafted PHEMA. A significant improvement in the grafting efficiency and the grafting percentage was achieved when a sequential grafting approach was taken, employing multiple UV exposures. Using this approach, the efficient chain extension from the grafted-PHEMA was possible without producing significant amounts of ungrafted PHEMA when low HEMA concentrations were used during each UV-exposure.     

Ag-Cu离子注入SiO2玻璃后形成纳米颗粒的研究

Ag、Cu离子经200和110keV加速后分别以5×1016和1.5×1017ions /cm2的剂量在室温下先后注入到非晶SiO2玻璃中.注入后样品的光学吸收谱显示两个吸收峰,其峰位为407和569nm,分别对应单独Ag和单独Cu纳米颗粒的等离子体共振吸收峰,样品在还原-保护气氛下退火后吸收峰峰强明显增加.样品的透射电镜选区电子衍射花样含有Ag、Cu两套衍射环,透射电镜的明场像观察到大量的纳米颗粒呈现出中心亮斑特征.在样品倾转过程中,中心亮斑特征依然存在,证实这种现象是离子辐照产生的纳米空位团簇.扫描透射电子显微镜高角环形暗场像进一步证实了这一点.综上所述,样品中形成了单Ag和单Cu包裹空位团簇的纳米颗粒.     

TEM and HRTEM evidence for the role of ligands in the formation of shape-controlled platinum nanoparticles

The morphology of platinum nanoparticles synthesized using an organometallic approach from PtMe(2) (C(8) H(12) ) is influenced by the nature of the ligands used as stabilizing agents. The use of long alkyl chain amines leads to the formation of multipodal nanoparticles that transform into compact nano-objects, adopting cubic, truncated cubic, or cuboctahedral shapes. In contrast, the use of diamine ligands allows the growth of compact (111) arrowlike faces, forming polycrystalline nanoparticles of an overall desert-rose aspect. Different reaction parameters are studied ([ligand]/[metal] ratio, temperature, solvent identity) in order to optimize the various shapes.     

Effect of annealing on the structural and optical properties of non-coated and silica-coated ZnS:Mn nanoparticles

The Mn²⁺-doped ZnS nanoparticles stabilized by sodium citrate were synthesized through a simple chemical route. Using the ZnS:Mn nanoparticles as seeds, the silica-coated ZnS:Mn nanocomposites were formed in isopropanol by the controlled hydrolysis of tetraethyl orthosilicate. The photoluminescence spectra confirmed that the Mn²⁺ ions were incorporated into the ZnS nanoparticles. The annealing effect on the structural and optical properties of these particles was studied over a range of 100–400 °C. The results of X-ray diffraction and photoluminescence showed that the silica shell not only improved the thermal stability but also resisted the lattice-deformation and oxidation of the particles. The thermal analysis further confirmed that the non-coated ZnS:Mn nanoparticles were unstable beyond 200 °C.