Glucose biosensors as models for the development of advanced protein-based biosensors

Glucose sensing is used as a model to explore the advantages and problems deriving from the use of either enzymes or sugar binding proteins to develop stable fluorescence biosensors. We report on a novel approach to address the problem of substrate consumption by sensors based on enzymes, namely the utilization of apo-enzymes as non-active forms of the protein which are still able to bind the substrate/ligand. We also review studies in which derivatization of a naturally thermostable sugar-binding protein with a fluorescent probe allows quantitative monitoring of glucose binding even after immobilization on a solid support.     

The development and application of FET-based biosensors

After having considered the general definition of biosensors, the specifications of one type are discussed here in more detail, namely the pH-sensitive ISFET, which is at present being clinically investigated for intravascular blood pH recording. Results, advantages and possible improvements will be discussed, as well as a prediction with respect to future developments of FET-based biosensors.     

氨基酸生物传感器的开发及应用研究进展

氨基酸是蛋白质的基本组成单元,对人和动物的营养健康十分重要,广泛应用于饲料、食品、医药和日化等领域。目前,氨基酸主要通过微生物发酵可再生原料生产,氨基酸产业是我国生物制造的重要支柱产业之一。氨基酸菌株主要通过随机诱变和代谢工程改造结合筛选获得。菌株生产水平进一步提高的核心限制之一是缺乏高效、快速和准确的筛选方法,因此,发展氨基酸菌株的高通量筛选方法对关键功能元件挖掘及高产菌株的创制筛选至关重要。本文综述了氨基酸生物传感器的设计,及其在功能元件、高产菌株的高通量进化筛选和代谢途径动态调控中的应用研究进展,讨论了现有氨基酸生物传感器存在的问题和性能提升改造策略,并展望了开发氨基酸衍生物生物传感器的重要性。     

In vivo biosensors: mechanisms,development, and applications

In vivo biosensors can recognize and respond to specific cellular stimuli. In recent years, biosensors have been increasingly used in metabolic engineering and synthetic biology, because they can be implemented in synthetic circuits to control the expression of reporter genes in response to specific cellular stimuli, such as a certain metabolite or a change in pH. There are many types of natural sensing devices, which can be generally divided into two main categories: protein-based and nucleic acid-based. Both can be obtained either by directly mining from natural genetic components or by engineering the existing genetic components for novel specificity or improved characteristics. A wide range of new technologies have enabled rapid engineering and discovery of new biosensors, which are paving the way for a new era of biotechnological progress. Here, we review recent advances in the design, optimization, and applications of in vivo biosensors in the field of metabolic engineering and synthetic biology.     

The development and applications of thermal biosensors for bioprocess monitoring

Enzyme thermistors are biosensors that use thermal resistors to measure the heat change caused by an enzymatic reaction. They combine the selectivity of enzymes with the sensitivity of biosensors and allow continuous analysis in a flow-injection mode. They can be used to monitor fermentation systems, biocatalysis, enzyme-catalysed synthesis and clinical and food technology. This article gives an overview of the general principles of enzyme thermistors, the sampling process and the ongoing developments in the field of bioprocess monitoring.     

Electrodeposited nonconducting polytyramine for the development of glucose biosensors

Biosensors with the composition of carbon/Prussian blue/(glucose oxidase+glutaraldehyde+polytyramine) were constructed. Before tyramine monomers were electropolymerized, glucose oxidase and tyramine monomers were cross-linked with glutaraldehyde onto the surface of Prussian-blue-modified electrodes. The constructed biosensors produced highly reproducible and stable devices. The biosensors exhibited neglectable decrease in current response after 10 repeated uses or after 1 month of dry storage. The resultant biosensors had a linear range of 0.1-1 mM glucose and a detection limit of 0.05 mM. Since the following electrocatalytic process proceeds at a low electrode potential (ca. -0.3 V vs Ag/AgCl), ascorbate and uric acid do not produce observable interfering signal for the determination of glucose.     

Towards development of chemosensors and biosensors with metal-oxide-based nanowires or nanotubes

The emerging nanotechnology has opened new exciting opportunities to explore analytical applications of the freshly prepared nanostructured materials. Among them, metal-oxide-based nanowires or nanotubes attracted great attention due to their one-dimensional (1D) morphology, extraordinary physical and chemical properties, which offer great promise in the development of chemical sensing or biosensing, facilitating the great improvement of the selectivity and sensitivity of the current methods. In this review, the recent advances in the development of sensors including gas sensors, humidity sensors, and immunosensors using semiconducting metal-oxide-based nanowires or nanotubes are highlighted. Titanate (H(2)Ti(3)O(7)) nanotubes are of multilayered structures with a nanometer-scale inner-core cavity exposed to the outer surface and display different oxidation states with possible redox-activity, which make them attractive for sensing. Therefore, the use of titanate nanotubes for the development of electrochemical sensors is overviewed. Finally, the prospects and challenge in the further exploration of nanoscaled sensors are discussed.     

Fluorescence sensing of intermolecular interactions and development of direct molecular biosensors

Molecular biosensors are devices of molecular size that are designed for sensing different analytes on the basis of biospecific recognition. They should provide two coupled functions - the recognition (specific binding) of the target and the transduction of information about the recognition event into a measurable signal. The present review highlights the achievements and prospects in design and operation of molecular biosensors for which the transduction mechanism is based on fluorescence. We focus on the general strategy of fluorescent molecular sensing, construction of sensor elements, based on natural and designed biopolymers (proteins and nucleic acids). Particular attention is given to the coupling of sensing elements with fluorescent reporter dyes and to the methods for producing efficient fluorescence responses.     

Molecular assembly of proteins and conjugated polymers: Toward development of biosensors

A molecular assembly in which a conjugated polymer is interfaced with a photodynamic protein is described. The conjugated polymer, functionalized with biotion, is designed such that it can be physisorbed on or chemically grown off a glass surface. The streptavidin-derivatized protein is immobilized on the biotinylated polymer matrix through the strong biotin-streptavidin interactions. The assembly, built on the surface of an optical fiber or on the inside walls of a glass capillary, forms an integral part of a biosensor for the detection of environmental pollutants such as organophosphorus-based insecticides. The Protein in the system can be replaced by any biological macromolecule of interest. We study one specific case, the enzyme alkaline phosphatase. The enzyme catalyzes a reaction producing an intermediate compound that chemiluminesces, and the chemiluminescence singnal is monitored to detect and quantify insecticides such as paraoxon and methyl parathion. Preliminary results indicate ppb level detection with response time less than 1 minute. (c) 1995 John Wiley & Sons, Inc.     

生物传感器在食源性致病菌检测中应用的研究进展

食源性致病菌作为引起食源性疾病的主要因素,受到人们的高度重视,发展简便、快速、高灵敏度和低成本的食源性致病菌检测方法对降低食源性疾病发病率具有重要意义。生物传感器技术是一种由多学科交叉渗透发展形成的全新微量分析技术,具有灵敏度高、分析速度快等特点,被广泛应用于食源性致病菌的检测。文中介绍了生物传感器的基本原理,综述了常见的生物传感器在食源性致病菌检测中的应用,并对其发展趋势进行了展望。     

Nanotechnology and biosensors

Nanotechnology is playing an increasingly important role in the development of biosensors. The sensitivity and performance of biosensors is being improved by using nanomaterials for their construction. The use of these nanomaterials has allowed the introduction of many new signal transduction technologies in biosensors. Because of their submicron dimensions, nanosensors, nanoprobes and other nanosystems have allowed simple and rapid analyses in vivo. Portable instruments capable of analyzing multiple components are becoming available. This work reviews the status of the various nanostructure-based biosensors. Use of the self-assembly techniques and nano-electromechanical systems (NEMS) in biosensors is discussed.     

检测环境污染物的适配体生物传感器研究进展

适配体生物传感器可利用适配体作为识别元件,将适配体的优良特性和目前先进的检测技术进行结合,例如光学、电化学纳米集成技术或生物膜干涉测量法,为其在有毒有害物质检测和环境实时监测领域构筑了良好应用前景。然而,适配体传感器的进一步应用仍有许多问题亟待解决,比如:环境的复杂性会对其应用产生限制;适配体固化到传感器表面的方式会影响适配体的结构和功能,从而影响检测效果。本文将主要研究适配体筛选策略的最新进展并对适配体传感器检测环境中小分子污染物的应用展开综述。     

Comparative electrochemical behaviour of biotin hydrazide and photobiotin. Importance in the development of biosensors

The cyclic voltammetric behaviour of biotin hydrazide and photobiotin on carbon paste electrodes has been studied. Biotin hydrazide presents an anodic and irreversible process, meanwhile photobiotin presents two, adsorptive in nature. This characteristic makes photobiotin desirable for following the interaction between biotin and streptavidin, being possible to detect a streptavidin concentration of 10(-12) M. The evidence of this reaction has been shown either directly in solution or on the electrode surface. Photobiotin as the molecule portable of analytical information and carbon paste as the solid support could be applied to the development of sensors based on the oxidation of this molecule.     

A novel signal transduction system for development of uric acid biosensors

Applied Microbiology and Biotechnology - Uric acid (UA) is an important biomarker for clinical diagnosis. Here, we present a novel signal transduction system for the development of UA biosensors...     

The application of neoglycopeptides in the development of sensitive surface plasmon resonance-based biosensors

The development of a biosensor based on surface plasmon resonance is described for the detection of carbohydrate-binding proteins in solution on a Biacore 2000 instrument, using immobilized glycopeptides as ligands. Their selection was based on previous screenings of solid-phase glycopeptide libraries with Ricinus communis agglutinin (RCA(120)) and human adhesion/growth-regulatory galectin-1 (h-Gal-1). Glycopeptides were immobilized on Au sensor chips functionalized with mixed self-assembled monolayers of different ratios of 11-mercapto-1-undecanol and 11-mercaptoundecanoic acid, and of 3-mercapto-1-propanol and 11-mercaptoundecanoic acid. The biosensors were optimized for the detection of RCA(120), and a detection limit of 0.13nM was obtained. Subsequent experiments with h-Gal-1 indicated a detection limit of at least 0.9nM for this lectin. Additionally, the effect of interfering proteins on the sensitivity of the optimized biosensor was investigated.     

Cytochrome P450 (CYP) enzymes and the development of CYP biosensors

Cytochrome P450s (CYPs) are a large family of heme-containing monooxygenase enzymes involved in the first-pass metabolism of drugs and foreign chemicals in the body. CYP reactions, therefore, are of high interest to the pharmaceutical industry, where lead compounds in drug development are screened for CYP activity. CYP reactions in vivo require the cofactor NADPH as the source of electrons and an additional enzyme, cytochrome P450 reductase (CPR), as the electron transfer partner; consequently, any laboratory or industrial use of CYPs is limited by the need to supply NADPH and CPR. However, immobilizing CYPs on an electrode can eliminate the need for NADPH and CPR provided the enzyme can accept electrons directly from the electrode. The immobilized CYP can then act as a biosensor for the detection of CYP activity with potential substrates, albeit only if the immobilized enzyme is electroactive. The quest to create electroactive CYPs has led to many different immobilization strategies encompassing different electrode materials and surface modifications. This review focuses on different immobilization strategies that have been used to create CYP biosensors, with particular emphasis on mammalian drug-metabolizing CYPs and characterization of CYP electrodes. Traditional immobilization methods such as adsorption to thin films or encapsulation in polymers and gels remain robust strategies for creating CYP biosensors; however, the incorporation of novel materials such as gold nanoparticles or quantum dots and the use of microfabrication are proving advantageous for the creation of highly sensitive and portable CYP biosensors.     

Luminescence biosensors

A novel optical biosensor for homogeneous immunoassay has been developed on the basis of the finding that electrochemical luminescence of pyrene-labelled antigen is extremely inhibited by immunochemical complexation. Electrochemical luminescence homogeneous immunoassay for human serum albumin (HSA), as a model analyte, was performed with a platinum plate electrode which was located in the vicinity of an optical fibre tip. HSA was determined in the concentration range of 3–25 × 10^?6 mol/I. To improve electrochemical luminescence measurement an optical fibre electrode has been developed by fabricating a transparent platinum film on the top of an optical fibre. The minimum detectable limit of luminol was 10^?11 mol/l with the optical fibre electrode. Luminol was applied as a label for homogeneous immunoassay.     

Optical biosensors

Different types of optical biosensor are critically assessed and compared, based on the belief that a comprehensive understanding of their possibilities—and limitations—is needed for their successful exploitation. © 1997 John Wiley & Sons, Ltd.