Stabilized Lipid Membrane Based Biosensors with Incorporated Enzyme for Repetitive Uses

This work reports a technique for the stabilization of lipid membrane based biosensors with incorporated enzyme that retains its activity for repetitive uses. Microporous filters composed of glass fibers were used as supports for the stabilization of these sensors. The lipid film is formed on the filter by polymerization using UV (ultraviolet) radiation prior its use. Methacrylic acid was the functional monomer, ethylene glycol dimethacrylate was the crosslinker and 2,2′‐azobis‐(2‐methylpropionitrile) was the initiator. The enzyme (acetylcholinesterase) is incorporated within this mixture prior to polymerization. The polymerization process takes place by using UV irradiation instead of heating at 60 °C the lipid mixture because this temperature might denature the enzyme. This method for preparation of stabilized lipid membranes was investigated using Raman spectroscopy. The results have indicated that the kinetics of polymerization are completed within 4 hours. The retain in activity of the enzyme was studied using electrochemical experiments which have shown that this mild technique of polymerization can now be used to incorporate a protein in these lipid membranes without loss of their activity. This will allow the practical use of the techniques for chemical sensing based on lipid membranes based biosensors and commercialization of these devices.     

Recent Progress on the Development of Biofuel Cells for Self‐Powered Electrochemical Biosensing and Logic Biosensing: A Review

Biofuel cells (BFCs) based on enzymes and microorganisms have been recently received considerable attention because they are recognized as an attractive type of energy conversion technology. In addition to the research activities related to the application of BFCs as power source, we have witnessed recently a growing interest in using BFCs for self‐powered electrochemical biosensing and electrochemical logic biosensing applications. Compared with traditional biosensors, one of the most significant advantages of the BFCs‐based self‐powered electrochemical biosensors and logic biosensors is their ability to detect targets integrated with chemical‐to‐electrochemical energy transformation, thus obviating the requirement of external power sources. Following my previous review (Electroanalysis­ 2012 , 24, 197–209), the present review summarizes, discusses and updates the most recent progress and latest advances on the design and construction of BFCs‐based self‐powered electrochemical biosensors and logic biosensors. In addition to the traditional approaches based on substrate effect, inhibition effect, blocking effect and gene regulation effect for BFCs‐based self‐powered electrochemical biosensors and logic biosensors design, some new principles including enzyme effect, co‐stabilization effect, competition effect and hybrid effect are summarized and discussed by me in details. The outlook and recommendation of future directions of BFCs‐based self‐powered electrochemical biosensors and logic biosensors are discussed in the end.     

Nanostructures of noble metals as functional materials in biosensors

Recent advancement in nanoscience and nanotechnologies inspired a wide spectrum of uses of nanodimensional materials ranging from industrial sector to biomedical applications. Inorganic nanomaterials made of noble metals, which are corrosion-resistant, are often included as electrode modifiers in designing electrochemical chemosensors and biosensors because of their unique catalytic, electric, and surface-related properties. This review summarizes the developments in electrochemical biosensors with integrated in their architecture metal nanostructures reported mainly during the last two years with a summary on some of the commonly used methods for the synthesis of metallic nanostructures. Nanodimensional noble metal structures might be considered as multipurpose electrode modifiers because of their abilities to act at the same time as electrocatalysts, signal amplifiers, and tools for immobilization and spatial orientation of redox proteins/enzymes or other type of bioreceptors.     

Biosensors and biochips: advances in biological and medical diagnostics

In the past two decades, the biological and medical fields have seen great advances in the development of biosensors and biochips capable of characterizing and quantifying biomolecules. This review is meant to provide an overview of the various types of biosensors and biochips that have been developed for biological and medical applications, along with significant advances over the last several years in these technologies. It also attempts to describe various classification schemes that can be used for categorizing the different biosensors and provide relevant examples of these classification schemes from recent literature.     

Biosensors and biochips: advances in biological and medical diagnostics

In the past two decades, the biological and medical fields have seen great advances in the development of biosensors and biochips capable of characterizing and quantifying biomolecules. This review is meant to provide an overview of the various types of biosensors and biochips that have been developed for biological and medical applications, along with significant advances over the last several years in these technologies. It also attempts to describe various classification schemes that can be used for categorizing the different biosensors and provide relevant examples of these classification schemes from recent literature.     

Nanomaterials as Pseudocatalysts in the Construction of Electrochemical Nonenzymatic Sensors for Healthcare: A Review

Enzymes, primarily different types of oxidases and most commonly peroxidase, are often used in the construction of biosensors. Enzymatic biosensors, due to their small size, easy to handle construction, accuracy and specificity, are powerful healthcare tools commonly used for the diagnosis of diseases for more than 20 years. Unfortunately, the loss of enzymatic activity during the immobilization of enzymes into biosensors has been a recent major problem. Hence, nonenzymatic electrochemical sensors based on organic and inorganic nanostructures have gained great attention in the last few years. In this short review, different types of nanostructures and nanocomposites and their practical applications in the construction of nonenzymatic electrochemical sensors in healthcare and diagnosis are described and summarized.     

Bilayer lipid membranes: An experimental system for biomolecular electronic devices development

The lipid bilayer postulated as the basic structural matrix of biological membranes is widely accepted. At present, the planar bilayer lipid membrane (BLM) together with spherical lipid bilayers (liposomes), upon suitable modification, serves as a most appropriate model for biological membranes. In recent years, advances in microelectronics and interest in ultrathin organic films, including BLMs and Langmuir-Blodgett (L-B) films, have resulted in a unique fusion of ideas toward the development of biosensors and transducers. Furthermore, recent trends in interdisciplinary studies in chemistry, electronics, and biology have led to a new field of research: biomolecular electronics. This exciting new field of scientific-technological endeavor is part of a more general approach toward the development of a new, post-semiconductor electronic technology, namely, molecular electronics with a long-term goal of molecular computers.

Recently, it has been demonstrated that BLMs, after suitable modification, can function as electrodes and exhibit nonlinear electronic properties. These and other experimental findings relevant to sensor development and to “biomolecular electronic devices” (BED) will be described in more details in the present review article. Also the potential use of the BLM system together with its modifications in the development of a new class of organic diodes, switches, biosensors, electrochemical photocells, and biofuel cells will be discussed. Additionally, this paper reports also a novel technique for obtaining BLMs (or lipid bilayers) on solid supports. The presence of solid support on one side of the BLM greatly enhances its mechanical stability, while retaining the dynamic properties of the lipid bilayer. Advantages of the new techniques for self-assembling amphiphilic molecules on rigid substrates are discussed in terms of their possible uses. It is evident that the new BLM system (s-BLMs) is potentially useful for technological applications in the area of biosensors and enzyme electrodes as well as molecular electronics.     

Electrochemical Biosensors for Cancer Biomarker Detection

Cancer is still one of the leading causes of death in the world. There are over 200 types of cancers currently known according to the National Cancer Institute. However, early diagnosis continues to be an important integral part of cancer treatment even though many advances in therapeutics have been made in the past decade. Quick diagnosis and early prevention are critical for the control of the disease status. Biomarkers are commonly indicative of a particular disease process and the cancer biomarkers are also widely used in oncology to help detecting the presence of various carcinomas. The detection of cancer biomarkers plays an important role in clinical diagnoses and evaluation of treatment for patients. Many immunoassay methods are developed for detection of cancer biomarkers. As the detection devices are normally viewed with high sensitivity, simple preparation and rapid response, electrochemical biosensors are increasingly used for the detection of cancer markers. This review describes the status, the latest research and trends of electrochemical sensors in the quantitation of cancer markers in recent years. In particular, the strategy to improve the sensitivities of the electrochemical biosensors by the aid of enzymatic amplification, nanoparticle amplification, ultilization of magnetic microspheres etc. is described herein. At last, we discuss some special features and limitations associated with the described systems that summarize the application and the development prospects of electrochemical immunoassay technology.     

Recent Advances in Electrochemical Sensors for Detecting Weapons of Mass Destruction. A Review

The detection of chemical warfare agents (CWA) has become a worldwide security concern in light of the many recent international threats utilizing nerve agents. Among a variety of detection methods that have been developed for CWA, electrochemical sensors offer the unrivaled merits of high sensitivity, specificity and operational simplicity. Recent insights into novel fabrication methodologies and electrochemical techniques have resulted in the demonstration of electrochemical sensors able to address many of the limitations of conventional methodologies. This article reviews recent advances and developments in the field of electrochemical biosensors based detection of nerve agent and their utility for decentralized threat detection. With continued innovations and attention to key challenges, it is expected that electrochemical sensors will play a pivotal role in the CWA detection scenario. This review concludes with the implications of the electrochemical sensing platforms along with future prospects and challenges.     

Recent Advances on Nanozyme-based Electrochemical Biosensors

Nanozymes are nanomaterials with enzyme-like catalytic activities. The unique features of nanozymes (such as high stability, low cost, large surface area for bioconjugation, ease of storage, and multi-functionalities) offer unprecedented opportunities for designing electrochemical biosensors. Recent years have witnessed the rapid development of nanozyme-based electrochemical biosensors. To highlight these achievements, this review first discusses the representative nanozymes including peroxidase mimics, oxidase mimics, hydrolase mimics, and superoxide dismutase mimics used in electrochemical biosensors. Then, it summarizes the bioanalytical applications for the detection of various analytes. Finally, current challenges and future research directions are summarized.     

基于层状双金属氢氧化物的电化学生物传感器研究进展

层状双金属氢氧化物（LDHs）具有开放的二维平面结构和良好的生物相容性,是非常适合于将生物酶固定在电极表面用于生物传感器的主体材料。本文介绍了酶在LDHs材料上的固定方法,综述了近年来基于这类二维层状材料的各种电化学生物传感器的研究进展,讨论了不同类型生物传感器的设计原理和电子传递机理,并对LDHs在电化学生物传感领域...     

Electrochemical detection coupled with high-performance liquid chromatography in pharmaceutical and biomedical analysis: a mini review

Recent advances in electrochemical detection techniques coupled with high-performance liquid chromatography (HPLC-ECD) in pharmaceutical and biomedical analysis are reviewed. ECD classification and modes including common amperometric, coulometric, conductimetric, and potentiometric detector, are outlined and the some typical examples of determinations in pharmaceutical and biomedical analysis are described. The electrochemical detection system can offer superior merits over other detectors commonly used with HPLC. These techniques have great potential owing to their prominent characteristics in high-throughput screening procedures of drugs in various matrices. Fundamental 67 references from last 5 years related with a field are cited in this review.     

Functionalized carbon nanotubes and nanofibers for biosensing applications

This review summarizes recent advances in electrochemical biosensors based on carbon nanotubes (CNTs) and carbon nanofibers (CNFs) with an emphasis on applications of CNTs. CNTs and CNFs have unique electric, electrocatalytic and mechanical properties, which make them efficient materials for developing electrochemical biosensors.We discuss functionalizing CNTs for biosensors. We review electrochemical biosensors based on CNTs and their various applications (e.g., measurement of small biological molecules and environmental pollutants, detection of DNA, and immunosensing of disease biomarkers). Moreover, we outline the development of electrochemical biosensors based on CNFs and their applications. Finally, we discuss some future applications of CNTs.     

双层磷脂膜的电化学性质及其在生物传感器中的应用

由于双层磷脂膜（BLM）可模仿自然界的生物细胞膜的生物相容性，成为物分子的天然固定化材料，因此生物传感器的研制领域显示出广泛的应用前景，本文介绍了BLM、s-BLM的电化学性质，制备技术，并评述了其在生物传感器的应用研究进展。     

Utilization of nanoparticle labels for signal amplification in ultrasensitive electrochemical affinity biosensors: A review

Nanoparticles with desirable properties not exhibited by the bulk material can be readily synthesized because of rapid technological developments in the fields of materials science and nanotechnology. In particular their highly attractive electrochemical properties and electrocatalytic activity have facilitated achievement of the high level of signal amplification needed for the development of ultrasensitive electrochemical affinity biosensors for the detection of proteins and DNA. This review article explains the basic principles of nanoparticle based electrochemical biosensors, highlights the recent advances in the development of nanoparticle based signal amplification strategies, and provides a critical assessment of the likely drawbacks associated with each strategy. Finally, future perspectives for achieving advanced signal simplification in nanoparticles based biosensors are considered.     

Rapid Detection of Vanillin in Alcoholic Beverages Using Stabilized Polymerized Lipid Film Based Biosensors

This work reports a technique for the rapid detection of vanillin in alcoholic beverages using stabilized lipid membrane based biosensors. Microporous filters composed of glass fibers (nominal pore sizes 0.7 and 1.0 μm) were used as supports for the polymerization of the lipid film and stabilization of these devices. The lipid film is formed on the filter by polymerization prior its use. Methacrylic acid was the functional monomer, ethylene glycol dimethacrylate was the crosslinker and 2,2′‐azobis‐(2‐methylpropionitrile) was the initiator. The response towards vanillin of the present stabilized lipid membrane biosensors composed of phosphatidylcholine was investigated. The stabilized lipid membranes provided artificial ion gating events in the form of transient signals and can be used again after storage in air. This has allowed the practical use of the technique for chemical sensing based on lipid film for the rapid detection of vanillin in wines and alcoholic beverages.     

Biosensing applications of clay-modified electrodes: a review

Two-dimensional layered inorganic solids, such as cationic clays and layered double hydroxides (LDHs), also defined as anionic clays, have open structures which are favourable for interactions with enzymes and which intercalate redox mediators. This review aims to show the interest in clays and LDHs as suitable host matrices likely to immobilize enzymes onto electrode surfaces for biosensing applications. It is meant to provide an overview of the various types of electrochemical biosensors that have been developed with these 2D layered materials, along with significant advances over the last several years. The different biosensor configurations and their specific transduction procedures are discussed.      

Application of Carbon Nanotubes in the Extraction and Electrochemical Detection of Organophosphate Pesticides: A Review

Recent trends and challenges in developing carbon nanotubes (CNT) based sensors and biosensors for the detection of organophosphate (OP) pesticides and other organic pollutants in water are reviewed. CNT have superior electrical, mechanical, chemical, and structural properties over conventional materials such as graphite. At the same time CNT based sensors and biosensors are more efficient compared to the existing traditional techniques such as high-performance liquid chromatography or gas chromatography, because they can provide rapid, sensitive, simple, and low-cost on-field detection. The measurement protocols can be based on enzymatic and non-enzymatic detection. The enzyme acetylcholinesterase (AChE) is used with CNT for fabricating ultrasensitive biosensors for OP detection involving different immobilization schemes such as adsorption, crosslinking, and layer-by-layer self-assembly. This protocol relies on measuring the degree of enzyme inhibition as means of OP quantification. The other enzyme used along with CNT for OP detection is organophosphate hydrolase (OPH) which hydrolyzes the OP into detectable species that can be measured by amperometric or potentiometric methods. Different forms of CNT electrode materials can be used for fabricating such electrodes such as pure CNT and composite CNT. Due to their large surface area and hydrophobicity, CNT have also been used for the extraction and non-enzymatic electrochemical detection of OP with very high efficiency. The application of CNT and their novel properties for the adsorption and electrochemical detection of OP compounds is discussed in detail.