Development of an Interdigitated Electrode-Based Disposable Enzyme Sensor Strip for Glycated Albumin Measurement

Glycated albumin (GA) is an important glycemic control marker for diabetes mellitus. This study aimed to develop a highly sensitive disposable enzyme sensor strip for GA measurement by using an interdigitated electrode (IDE) as an electrode platform. The superior characteristics of IDE were demonstrated using one microelectrode of the IDE pair as the working electrode (WE) and the other as the counter electrode, and by measuring ferrocyanide/ferricyanide redox couple. The oxidation current was immediately reached at the steady state when the oxidation potential was applied to the WE. Then, an IDE enzyme sensor strip for GA measurement was prepared. The measurement of fructosyl lysine, the protease digestion product of GA, exhibited a high, steady current immediately after potential application, revealing the highly reproducible measurement. The sensitivity (2.8 nA µM−1) and the limit of detection (1.2 µM) obtained with IDE enzyme sensor strip were superior compared with our previously reported sensor using screen printed electrode. Two GA samples, 15 or 30% GA, corresponding to healthy and diabetic levels, respectively, were measured after protease digestion with high resolution. This study demonstrated that the application of an IDE will realize the development of highly sensitive disposable-type amperometric enzyme sensors with high reproducibility.

Employment of 1-Methoxy-5-Ethyl Phenazinium Ethyl Sulfate as a Stable Electron Mediator in Flavin Oxidoreductases-Based Sensors

In this paper, a novel electron mediator, 1-methoxy-5-ethyl phenazinium ethyl sulfate (mPES), was introduced as a versatile mediator for disposable enzyme sensor strips, employing representative flavin oxidoreductases, lactate oxidase (LOx), glucose dehydrogenase (GDH), and fructosyl peptide oxidase (FPOx). A disposable lactate enzyme sensor with oxygen insensitive Aerococcus viridans-derived engineered LOx (AvLOx), with A96L mutant as the enzyme, was constructed. The constructed lactate sensor exhibited a high sensitivity (0.73 ± 0.12 μA/mM) and wide linear range (0–50 mM lactate), showings that mPES functions as an effective mediator for AvLOx. Employing mPES as mediator allowed this amperometric lactate sensor to be operated at a relatively low potential of +0.2 V to 0 V vs. Ag/AgCl, thus avoiding interference from uric acid and acetaminophen. The lactate sensors were adequately stable for at least 48 days of storage at 25 °C. These results indicated that mPES can be replaced with 1-methoxy-5-methyl phenazinium methyl sulfate (mPMS), which we previously reported as the best mediator for AvLOx-based lactate sensors. Furthermore, this study revealed that mPES can be used as an effective electron mediator for the enzyme sensors employing representative flavin oxidoreductases, GDH-based glucose sensors, and FPOx-based hemoglobin A1c (HbA1c) sensors.

Electrochemical Sensors Fabricated by Electrospinning Technology: An Overview

Nanofibers or nanofibrous membranes prepared by electrospinning possess many attractive properties, including excellent mechanical properties, high specific surface area and high porosity, making them attractive for sensor application, especially for the electrochemical sensors. Many nanomaterials are used as additives to improve the conductivity, sensitivity and selectivity of sensors. Based on the different modifiers of electrode materials, electrochemical sensors can be divided into enzyme sensors and non-enzyme sensors. In this review, we summarize the recent progress of the electrochemical sensors fabricated by electrospinning, including hydrogen peroxide (H2O2) sensors, glucose sensors and other sensors. In addition, the sensing mechanisms of various electrochemical sensors are introduced in detail. Finally, future research directions of electrochemical sensors based on electrospinning and the challenges faced by large-scale applications of electrospun electrochemical sensors are presented.

Tailoring pore structures with optimal mesopores to remarkably promote DNA adsorption guiding the growth of active Mn3(PO4)2 toward sensitive superoxide biomimetic enzyme sensors

Optimizing the structure of mesopores to greatly boost Mn3(PO4)2–DNA adsorption for a highly sensitive and selective biomimetic enzyme O2˙− sensor.

DEVELOPMENT OF A BIOSENSOR OF UREA WITH THE APPLICATION OF POLYMER TECHNOLOGIES FOR BLOOD AND URINE ANALYSIS

Based on polymeric nanotechnologies, enzyme sensors and microreactors have been developedin the way, that they can determine urea in liquids. The technology of manufacturing an enzymatic biosensor does not differ significantly from the known technology of manufacturing microcapsules with an enzyme by the laer-by-laer method. This allows us, when constructing a biosensor, to use the information obtained on encapsulated enzymes by other authors. It is shown that urea biosensor is able to work for a long time (up to 2 months) without significant loss of enzyme activity. Polymer technology for manufacturing sensors is less laborious and expensive compared to other similar technologies. We propose to develop biosensor devices – urea analyzers with polymer enzyme chips for express diagnostics of biological fluids (blood, urine). One of the significant results of this work from our point of view is two factors. The first factor is the optimization of the conditions for the production of a functionally active enzyme immobilized in a polyelectrolyte coating, when the enzyme after the immobilization procedure shows an activity comparable to that of a freshly prepared free enzyme. Such a result will allow reducing the cost of enzymes when creating a sensitive layer of the developed urea analyzer. And the second factor is that the polymer coating with the enzyme is able to work not only as an enzyme electrode, but also as an enzyme microreactor, without decreasing the rate of signal registration after passing the catalytic urease-urea reaction.

Forces, energetics, and dynamics of conjugated-carbon ring tethers adhered to CNTs: a computational investigation

The strength and nature of the interactions between carbon nanotubes (CNTs) and molecular tethers plays a vital role in technology such as CNT–enzyme sensors.