An amperometric biosensor for glucose based on electrodeposited redox polymer/glucose oxidase film on a gold electrode

Electrochemical impedimetric biosensors, featuring the use of Room Temperature Ionic Liquids (RTILs): Special focus on non-faradaic sensing

Over the last decade, significant advancements have been made in the field of biosensing technology. With the rising demand for personalized healthcare and health management tools, electrochemical sensors are proving to be reliable solutions; specifically, impedimetric sensors are gaining considerable attention primarily due to their ability to perform label-free sensing. The novel approach of using Room Temperature Ionic Liquids (RTILs) to improve the sensitivity and stability of these detection systems makes long-term continuous sensing feasible towards a wide range of sensing applications, predominantly biosensing. Through this review, we aim to provide an update on current scientific progress in using impedimetric biosensing combined with RTILs for the development of sensitive biosensing platforms. This review also summarizes the latest trends in the field of biosensing and provides an update on the current challenges that remain unsolved.

Lipase, Phospholipase, and Esterase Biosensors (Review)

A biosensor is a device composed by a biological recognition element and a transducer that delivers selective information about a specific analyte. Technological and scientific advances in the area of biology, bioengineering, catalysts, electrochemistry, nanomaterials, microelectronics, and microfluidics have improved the design and performance of better biosensors. Enzymatic biosensors based on lipases, esterases, and phospholipases are valuable analytical apparatus which have been applied in food industry, oleochemical industry, biodegradable polymers, environmental science, and overall the medical area as diagnostic tools to detect cholesterol and triglyceride levels in blood samples. This chapter reviews recent developments and applications of lipase-, esterase-, and phospholipase-based biosensors.

Immobilization of glucose oxidase onto gelatin for biosensor construction

The properties of a glucose biosensor made by immobilization of glucose oxidase onto gelatin in a layer of electrochemically deposited polyaniline have been investigated. Glucose oxidase was immobilized within gelatin cross-links with chromium(III) acetate. The glucose oxidase biosensor was developed by forming a polyaniline-deposited electrode surface as support for the immobilized enzyme gel, in order to increase its durability. The polyaniline/gelatin/glucose oxidase biosensor has been characterized using chemical and electrochemical methods. Temperature, pH, cross-linking agent concentration, enzyme concentration, kinetic properties, reusability and the effect of electro-active compounds were among the parameters studied. The response time of the glucose oxidase biosensor is 90 s, the detection limit is below 1 mmol/dm3 and the sensor can be used 20 times within a 2-month period without losing its stability.

Lipase and phospholipase biosensors: a review

Recent advances in the field of biology, electronics, and nanotechnology have improved the development of biosensors. A biosensor is a device composed of a biological recognition element and a sensor element. Biosensor applications are becoming increasingly important in areas such as biotechnology, pharmaceutics, food, and environment. Lipases and phospholipases are enzymes which have been used widely in food industry, oleochemical industry, biodegradable polymers, detergents, and other applications. In the medical industry, lipases and phospholipases are used as diagnostic tools to detect triglycerides, cholesterol, and phospholipids levels in blood samples. Therefore, the development of lipase and phospholipase biosensors is of paramount importance in the clinical area. This chapter introduces the reader into the preliminaries of biosensor and reviews recent developments of lipase and phospholipase biosensors.

Modulation of fibroblast inflammatory response by surface modification of a perfluorinated ionomer

An ideal surface for implantable glucose sensors would be able to evade the events leading to chronic inflammation and fibrosis, thereby extending its utility in an in vivo environment. Nafion™, a perfluorinated ionomer, is the membrane material preferred for in situ glucose sensors. Unfortunately, the surface properties of Nafion™ promote random protein adsorption and eventual foreign body encapsulation, thus leading to loss of glucose signal over time. Details of the techniques to render Nafion™ nonprotein fouling are given in a previous article [T. I. Valdes et al., Biomaterials 29, 1356 (2008)]. Once random protein adsorption is prevented, a biologically active peptide can be covalently bonded to the treated Nafion™ to induce cellular adhesion. Cellular responses to these novel decorated Nafion™ surfaces are detailed here, including cell viability, cell spreading, and type I collagen synthesis. Normal human dermal fibroblasts (NHDFs) were cultured on control and modified Nafion™ surfaces. Findings indicate that Nafion™ modified with 10% 2-hydroxyethyl methacrylate and 90% tetraglyme created a nonfouling surface that was subsequently decorated with the YRGDS peptide. NHDFs were shown to have exhibited decreased type I collagen production in comparison to NHDF cells on unmodified Nafion™ surfaces. Here, the authors report evidence that proves that optimizing conditions to prevent protein adsorption and enhance cellular adhesion may eliminate fibrous encapsulation of an implant.

Assembling Amperometric Biosensors for Clinical Diagnostics

Clinical diagnosis and disease prevention routinely require the assessment ofspecies determined by chemical analysis. Biosensor technology offers several benefits overconventional diagnostic analysis. They include simplicity of use, specificity for the targetanalyte, speed to arise to a result, capability for continuous monitoring and multiplexing,together with the potentiality of coupling to low-cost, portable instrumentation. This workfocuses on the basic lines of decisions when designing electron-transfer-based biosensorsfor clinical analysis, with emphasis on the strategies currently used to improve the deviceperformance, the present status of amperometric electrodes for biomedicine, and the trendsand challenges envisaged for the near future.

An electrochemical investigation of glucose oxidase at a CdS nanoparticles modified electrode

The direct electrochemistry of glucose oxidase (GOD) adsorbed on a CdS nanoparticles modified pyrolytic graphite electrode was investigated, where the enzyme demonstrated significantly enhanced electron-transfer reactivity. GOD adsorbed on CdS nanoparticles maintained its bioactivity and structure, and could electro-catalyze the reduction of dissolved oxygen, which resulted in a great increase of the reduction peak current. Upon the addition of glucose, the reduction peak current decreased, which could be used for glucose detection. Performance and characteristics of the fabricated glucose biosensor were assessed with respect to detection limit, sensitivity, storage stability and interference exclusion. The results showed that the fabricated biosensor was sensitive and stable in detecting glucose, indicating that CdS nanoparticle was a good candidate material for the immobilization of enzyme in glucose biosensor construction.

Tuning the redox and enzymatic activity of glucose oxidase in layered organic films and its application in glucose biosensors

Glucose oxidase was embedded in organic films through a layer-by-layer approach, where the enzyme demonstrated significantly enhanced electron-transfer reactivity and finely tuned enzymatic activity. An unmediated, reagentless glucose biosensor was accordingly prepared with two polyethylenimine/glucose oxidase bilayers-modified pyrolytic graphite electrode. A calibration linear range of glucose was 0.5-8.9 mM with a detection limit of 50 microM and sensitivity of 0.76 microA mM(-1).