免标记光学纳米生物传感器的研究

利用发光稳定的多孔硅,当蛋白质溶液固定到多孔硅表面时,其发光强度和反射光谱的峰位会随着被测物质量浓度的变化而发生变化的特性。制备免标记光学纳米生物传感器来检测牛血清白蛋白（BSA）,把不同质量浓度的BSA溶液固定到多孔硅上测量反射光谱的峰位和荧光强度的变化。实验结果表明：反射光谱的峰位与牛血清白蛋白的浓度呈线性关系：y=1．4189x＋366．31,R^2=0．9898;荧光强度的降低量与BSA溶液的浓度呈线性关系,检测限为8×10^-9 mol／L。     

多孔硅Bragg反射镜适配子生物传感器检测心肌肌钙蛋白I

通过脉冲腐蚀法制备多孔硅Bragg反射镜,将心肌肌钙蛋白I（cTnI）适配子共价固定到多孔硅Bragg反射镜的孔洞中,发现适配子能与cTnI分子特异性结合。定量分析不同浓度的cTnI与适配子结合后多孔硅Bragg反射镜的反射谱峰位的红移情况。结果表明：基于多孔硅Bragg反射镜适配子生物传感器的光学检测具有良好的特异性,且具有免标记及检测时间短等优异性能。传感器的线性检测范围0．05-4nmol／L,最低检测限为0．05nmol／L。     

多孔硅Bragg反射镜适配子生物传感器检测心肌肌钙蛋白Ⅰ

通过脉冲腐蚀法制备多孔硅Bragg反射镜,将心肌肌钙蛋白Ⅰ(cTnⅠ)适配子共价固定到多孔硅Bragg反射镜的孔洞中,发现适配子能与cTnⅠ分子特异性结合.定量分析不同浓度的cTnⅠ与适配子结合后多孔硅Bragg反射镜的反射谱峰位的红移情况.结果表明:基于多孔硅Bragg反射镜适配子生物传感器的光学检测具有良好的特异性,且具有免标记及检测时间短等优异性能.传感器的线性检测范围0.05～4 nmol/L,最低检测限为0.05 nmol/L.     

纳米多孔硅阻抗生物传感器的研究

构建了1种基于多孔硅材料,无需标记的纳米生物传感器,用于对牛血清白蛋白分子进行检测。通过对多孔硅进行表面处理,形成氧化膜,将抗体固定到多孔硅氧化层表面。在磷酸盐缓冲液中,通过电化学检测系统检测加入抗原后,传感器的阻抗值的变化。磷酸缓冲液（PBS）/抗体-氧化层/硅,构成电解液/绝缘层/半导体（electro-lyte-insulator-semiconductor,EIS）结构。传感器的线性检测范围为0.01～0.27mg/mL,检测限为0.01mg/mL。     

免标记荧光适体传感器的研究进展

核酸适体在治疗、诊断和生物传感等领域都引起了强烈的关注和广泛的应用。与传统的识别元素-- 抗体相比较,适体展现 出很多的优点：尺寸小,化学性质稳定,容易制备和修饰。更重要的是适体在生物传感的设计上更为灵活,因此,产生了很多高选 择性、高灵敏度的新型适体传感器。目前,很多的检测手段都被应用到适体传感器中,其中荧光的检测手段占有重要的地位。虽然 荧光适体传感器已经取得了重大的进展,但是荧光标记给传感器的设计带来很多的不便,因此,免标记的荧光适体传感器备受关 注。在本文中,我们将对免标记的荧光适体传感器的研究进展进行综述,为分析工作者发展更加灵敏、更加简单、更加应用广泛的 免标记荧光适体传感器提供依据。     

适配子纳米生物传感器在青霉素检测中的应用

通过脉冲腐蚀法对硅片进行多孔硅的制备,利用玻片通过对共价法、离子吸附法和APTES修饰的戊二醛交联法3种固定适配子方法的对比,以确定较好的固定青霉素适配子的方法。将适配子固定在多孔硅上后,利用交流阻抗法对加入青霉素前后传感器阻抗值进行测定、对比,构建等效电路并进行阻抗拟合。对多孔硅传感器的Nyqu ist谱图进行分析以确定多孔硅表面成功固定了青霉素适配子,从而证明构建纳米生物传感器成功。传感器的线性检测范围为0.05~0.2 mg/L,检测限为0.05 mg/L。     

多孔硅适配子生物传感器的电化学研究

构建1种用于快速检测四环素的新型电化学纳米多孔硅(PS)生物传感器。通过脉冲腐蚀法制得多孔硅基片,将适配子固定于其上,这种四环素适配子能够特异性识别四环素分子,并引起阻抗值的变化。利用电化学交流阻抗法比较固定适配子前后硅片表面阻抗值的变化,以及在体系中加入不同浓度四环素后阻抗谱的变化。选择1个合适的等效电路对测得的阻抗数据进行拟合,获得了四环素浓度与阻抗值的变化规律。传感器的线性检测范围为2.079~62.37 nmol/L,检测限为2.079 7 nmol/L。     

硅纳米线在生物传感器中的应用概述

硅纳米线(SiNW)作为一种新型一维纳米材料,具有高比表面积、高稳定性等特点,在传感器领域得到了重视和研究。随着硅纳米线制备工艺优化、修饰方式多样化,以硅纳米线为载体的生物传感器被应用到了金属离子检测、蛋白质检测等诸多领域,较为优良的生物兼容性为生物学研究中的单细胞动态、实时监测提供了途径,电学、光学等不同检测手段也促进了硅纳米线生物传感器的机制研究。在生物化学物质传感检测中,传感器的敏感性、专一性和稳定性是衡量其性能的重要指标。硅纳米线化学性质稳定,为传感器的制备提供了良好的平台,在不同的应用场景中,传感器对硅纳米线的表面修饰提出了较高的要求。为此,研究人员提出了不同的传感机制。在电学信号传感方式中,硅纳米线场效应管(SiNW-FET)通过测量硅纳米线表面电荷变化引发的电导率变化,实现了对目标物质的超灵敏检测。在光学信号传感方式中,荧光分子识别应用较广,当目标物质与受体结合后通过荧光的增强、猝灭,波长的移动等多种方式传递信号,响应较快、检测手段较为便捷。对硅纳米线场效应管生物传感器和硅纳米线荧光传感器的机制与应用进行了概述,对今后硅纳米线在生物传感领域的发展提出了展望。     

硅纳米线在生物传感器中的应用概述

硅纳米线(SiNW)作为一种新型一维纳米材料,具有高比表面积、高稳定性等特点,在传感器领域得到了重视和研究.随着硅纳米线制备工艺优化、修饰方式多样化,以硅纳米线为载体的生物传感器被应用到了金属离子检测、蛋白质检测等诸多领域,较为优良的生物兼容性为生物学研究中的单细胞动态、实时监测提供了途径,电学、光学等不同检测手段也促...     

克服硅纳米线场效应管生物传感器德拜屏蔽效应的研究进展

硅纳米线场效应管(silicon nanowire field-effect transistor,SiNW-FET)生物传感器已成功用于蛋白质、核酸、糖类等多种生物分子的检测,并且具有超高灵敏度、高特异性、免标记、即时响应等检测优点。但是,半导体器件德拜屏蔽效应的存在严重影响Si NW-FET生物传感器对血液样品中生物分子检测的灵敏度,尤其对于蛋白质分子的检测,并且其在很大程度上阻碍了Si NW-FET生物传感器的实际应用。目前有效克服德拜屏蔽效应并实现血液样品中蛋白质分子检测的方法主要包括稀释法、去盐法、目标蛋白提纯法、应用渗透性生物分子聚合物层法、裁剪抗体法和适配子替代法。     

Application of an interferometric biosensor chip to biomonitoring an endocrine discruptor

RecombinantE. coli ACV 1003 (recA::lacZ) releasing β-galactosidase by a SOS regulon system, when exposed to DNA-damaging compounds, have been used to effectively monitor endocrine disruptors. Low enzyme activity of less than 10 units/mL, corresponding to a μg/L (ppb) range of an endocrine disruptor (tributyl tin, bisphenol A,etc.), can be rapidly determined, not by a conventional time-consuming and tedious enzyme assay, but by an alternative interferometric biosensor. Heavily boron-doped porous silicon for application as an interferometer, was fabricated by etching to form a Fabry-Perot fringe pattern, which caused a change in the refractive index of the medium including β-galactosidase. In order to enhance the immobilization of the porous silicon surface, a calyx crown derivative (ProLinker A) was applied, instead of a conventional biomolecular affinity method using biotin. This resulted in a denser linked formation. The change in the effective optical thickness versus β-galactosidase activity, showed a linear increase up to a concentration of 150 unit β-galactosidase/mL, unlike the sigmoidal increase pattern observed with the biotin.     

Amperometric glucose biosensor based on polymerized ionic liquid microparticles

A glucose amperometric biosensor based on the immobilization of glucose oxidase (GOx) in microparticles prepared by polymerization of the ionic liquid 1-vinyl-3-ethyl-imidazolium bromide (ViEtIm⁺Br⁻) using the concentrated emulsion polymerization method has been developed. The polymerization of the emulsion dispersed phase, in which the enzyme was dissolved together with the ionic liquid monomer, provides poly(ViEtIm⁺Br⁻) microparticles with entrapped GOx. An anion-exchange reaction was carried out for synthesizing new microparticles of poly(ViEtIm⁺(CF₃SO₂)₂N⁻) and poly(ViEtIm⁺BF₄⁻). The enzyme immobilization method was optimized for biosensor applications and the following optimal values were determined: pH 4.0 for the synthesis medium, 1.23 M monomer concentration and 3.2% (w/w) cross-linking content. The performance of the biosensor as a function of some analytical parameters such as pH and temperature of the measuring medium, and enzymatic load of the microparticles was also investigated. The effect of the substances which are present in serum samples such as uric and ascorbic acid was eliminated by using a thin Nafion layer covering the electrode surface. The biosensor thus prepared can be employed in aqueous and in non-aqueous media with satisfactory results for glucose determination in human serum samples. The useful lifetime of this biosensor was 150 days.     

A mediator-free phenol biosensor based on immobilizing tyrosinase to ZnO nanoparticles

A mediator-free phenol biosensor was developed. The low-isoelectric point tyrosinase was adsorbed on the surface of high-isoelectric point ZnO nanoparticles (nano-ZnO) facilitated by the electrostatic interactions and then immobilized on the glassy carbon electrode via the film forming by chitosan. It was found that the nano-ZnO matrix provided an advantageous microenvironment in terms of its favorable isoelectric point for tyrosinase loading and the immobilized tyrosinase retaining its activity to a large extent. Moreover, there is no need to use any other electron mediators. Phenolic compounds were determined by the direct reduction of biocatalytically generated quinone species at -200mV (vs. saturated calomel electrode). The parameters of the fabrication process and the various experimental variables for the enzyme electrode were optimized. The resulting biosensor can reach 95% of steady-state current within 10s, and the sensitivity was as high as 182microAmmol(-1)L. The linear range for phenol determination was from 1.5x10(-7) to 6.5x10(-5)molL(-1) with a detection limit of 5.0x 10(-8)molL(-1) obtained at a signal/noise ratio of 3. In addition, the apparent Michaelis-Menten constant (K(m)(app)) and the stability of the enzyme electrode were estimated. The performance of the developed biosensor was compared with that of biosensors based on other immobilization matrices.     

Glucose biosensor based on polyaniline synthesized in ionic liquid

The use of good electro-active polyaniline at high pH for immobilizing glucose oxidase is reported. The response current increased with increasing potential from 0.35 to 0.70 V. The maximum response current occurred at about pH 7.0. The relationship between response current and the glucose concentration was linear from 0.005 to 10.0 mmol dm^?3. The Michaelis–Menten constant K_m', maximum response current i_max and the apparent activation energy (E_a) were 31.59 mmol dm^?3, 21.28 µA and 32.58 kJ mol^?1, respectively. The response currents of the biosensor increased with increasing temperature. The biosensor was characterized by FTIR, UV-Vis spectra and AC impedance.     

Urea potentiometric biosensor based on modified electrodes with urease immobilized on polyethylenimine films

The development of a new electrochemical sensor consisting in a glass-sealed metal microelectrode coated by a polyethylenimine film is described. The use of polymers as the entrapping matrix for enzymes fulfils all the requirements expected for these materials without damaging the biological material. Since enzyme immobilization plays a fundamental role in the performance characteristics of enzymatic biosensors, we have tested four different protocols for enzyme immobilization to determine the most reliable one. Thus the characteristics of the potentiometric biosensors assembled were studied and compared and it appeared that the immobilization method leading to the most efficient biosensors was the one consisting in a physical adsorption followed by reticulation with dilute aqueous glutaraldehyde solutions. Indeed, the glutaraldehyde immobilized urease sensor provides many advantages, compared to the other types of sensors, since this type of urea biosensor exhibits short response times (15–30 s), sigmoidal responses for the urea concentration working range from 1×10^−2.5 to 1×10^−1.5 M and a lifetime of 4 weeks.     

Resonant mirror biosensor detection method based on yessotoxin-phosphodiesterase interactions

Yessotoxin (YTX) is a generic name for a group of lipophilic compounds recently discovered and chemically characterized. Association measurements were done in a resonant mirror biosensor. The instrument detects changes in the refractive index and/or thickness occurring within a few hundred nanometers form the sensor surface where a molecule is attached. We used aminosilane surfaces where phosphodiesterase 3',5'-cyclic-nucleotide-specific from bovine brain (PDEs) was immobilized. Over this immobilized ligand different amounts of YTX were added and typical association curve profiles were observed. These association curves fit a pseudo-first-order kinetic equation where the apparent association rate constant (k(on)) can be calculated. The value of this constant increases with YTX concentration. From the representation of k(on) versus YTX concentration we obtained the association rate constant (k(ass)) 248+/-40 M(-1)s(-1) and the dissociation rate constant (k(diss)) 9.36 x 10(-4)+/-1.72 x 10(-4)s(-1). From these values the kinetic equilibrium dissociation constant (K(D)) for YTX-PDEs association can be calculated. The value of this last constant is 3.74 x 10(-6)+/-8.25 x 10(-8)M YTX. The PDE-YTX association was used as a method suitable for determination of the toxin concentration in a shellfish sample. The assay had sufficient sensitivity and can be used on simple shellfish extracts.     

Taste receptor cell-based biosensor for taste specific recognition based on temporal firing

Taste receptor cells are the taste sensation elements expressing sour, salty, sweet, bitter and umami receptors, respectively. There are cell-to-cell communications between different types of cells. Nevertheless, the mechanism of taste sensation and taste information coded by taste receptor cell is not well understood at present and it is a long-standing issue. In order to explore taste sensation and analyze taste-firing responses from another point of view, we present a promising biomimetic taste receptor cell-based biosensor. The temporal firing responses to different tastants are recorded. Meanwhile, we investigate the firing rate and temporal firing of taste receptor cells. The experimental results are consistent with that from patch clamp and molecular biology experiment. Firing rate is dependent on the concentration of stimulus. PCA analysis (principal component analysis) of the temporal firing responses shows that the responses from different types of taste receptor cells can be distinguished. Furthermore, exogenous ATP is applied to mimic the effects of transmitter ATP (adenosine triphosphate) released from type II cells onto type III cells. Both enhanced and inhibitory effects on spontaneous firing are observed. This novel biomimetic hybrid biosensor provides a potential solution to investigate the taste sensation and coding mechanisms in a non-invasive way.