Conductive single enzyme nanocomposites prepared by in-situ growth of nanoscale polyaniline for high performance enzymatic bioelectrode.

Enzyme-based electrochemical biosensors hold great promise for applications in health/disease monitoring, drug discovery, and environmental monitoring. However, inherently non-conductive nature of proteinaceous enzymes often hampers effective electron transfer at enzyme-electrode interface, limiting biosensor performance of enzyme bioelectrodes. To address this problem, we present an approach to synthesize polyaniline (PAN)-based conductive single enzyme nanocomposites of glucose oxidase (GOx) (denoted as PAN-GOx).

Controlled growth of redox polymer network on single enzyme molecule for stable and sensitive enzyme electrode.

The electrochemical applications of enzymes are often hampered by poor enzyme stability and low electron conductivity. In this work, a novel enzyme nanogel based on atom transfer radical polymerization (ATRP) has been developed for highly sensitive detection of glucose based on ferrocene (Fc) embedded in crosslinked polymer network nanogel. Enzyme surfaces are successively modified with Br initiator, and then in situ atom transfer radical polymerization (ATRP) was performed to build up crosslinked polyacrylamide network.

Phenolic Tyrosinase Substrate with a Formal Potential Lower than That of Phenol to Obtain a Sensitive Electrochemical Immunosensor.

The high and selective catalytic activities of tyrosinase (Tyr) have frequently led to its application in sensitive biosensors. However, in affinity-based biosensors, the use of Tyr as a catalytic label is less common compared to horseradish peroxidase and alkaline phosphatase owing to the fact that phenolic Tyr substrates have yet to be investigated in detail. Herein, four phenolic compounds that have lower formal potentials than phenol were examined for their applicability as Tyr substrates, and three reducing agents were examined as potential strong reducing agents for electrochemical-chemical (EC) redox cycling involving an electrode, a Tyr product, and a reducing agent.

Boosting electrochemical immunosensing performance by employing acetaminophen as a peroxidase substrate.

In horseradish peroxidase (HRP)-based electrochemical immunosensing, an appropriate HRP substrate needs to be chosen to obtain a high electrochemical signal-to-background ratio. This is limited by the unwanted electrochemical reduction of HO, oxidation of the substrate, and the slow electrochemical reduction of the product. Herein, we report acetaminophen (AMP) as a new HRP substrate that allows for highly sensitive immunosensing.

Highly sensitive detection of hydrazine by a disposable, Poly(Tannic Acid)-Coated carbon electrode.

We propose an electrochemical sensor based on the enhanced electrocatalytic oxidation exhibited on a functionalized poly(tannic acid) coating to detect hydrazine. Tannic acid, a naturally abundant and low-cost polyphenol, was enzymatically polymerized with horseradish peroxidase and subsequently adsorbed on a disposable screen-printed carbon electrode with a short incubation time (30 min). The fabrication method proved to be reproducible (4.

Universal method for direct bioconjugation of electrode surfaces by fast enzymatic polymerization.

We report HRP-catalyzed polymerization of Tannic acid (TA) and application of the poly (Tannic acid) (p(TA)) as a versatile platform for covalent immobilization of biomolecules on various electrode surfaces based on electrochemical oxidation of the p(TA) and subsequent oxidative coupling reactions with the biomolecules. We also used this method for capturing cancer cells through a linker molecule, folic acid (FA). Furthermore, we have demonstrated that enhanced electrocatalytic activity of the p(TA)-modified surface could be used for simultaneous electrochemical determination of biologically important electroactive molecules such as ascorbic acid (AA), dopamine (DA), and uric acid (UA).

Washing-Free Displacement Immunosensor for Cortisol in Human Serum Containing Numerous Interfering Species.

Simple and sensitive competitive immunosensors for small molecules are difficult to obtain, especially in serum containing numerous interfering species (ISs) with different concentrations. Herein, we report a washing-free and sensitive (competitive) displacement immunosensor for cortisol in human serum, based on electron mediation of Os(bpy)Cl between an electrode and a redox label [oxygen-insensitive diaphorase (DI)] (i.e.

Immunosensor Employing Stable, Solid 1-Amino-2-naphthyl Phosphate and Ammonia-Borane toward Ultrasensitive and Simple Point-of-Care Testing.

Biosensors for ultrasensitive point-of-care testing require dried reagents with long-term stability and a high signal-to-background ratio. Although ortho-substituted diaromatic dihydroxy and aminohydroxy compounds undergo fast redox reactions, they are not used as electrochemical signaling species because they are readily oxidized and polymerized by dissolved oxygen. In this report, stable, solid 1-amino-2-naphthyl phosphate (1A2N-P) and ammonia-borane (HN-BH) are respectively employed as a substrate for alkaline phosphatase (ALP) and a reductant for electrochemical-chemical (EC) redox cycling.

Redox cycling-amplified enzymatic Ag deposition and its application in the highly sensitive detection of creatine kinase-MB.

This communication reports a novel enzymatic Ag-deposition scheme combined with chemical-chemical redox cycling by reduced β-nicotinamide adenine dinucleotide. This novel scheme allows a higher Ag-deposition rate than a scheme using only enzymatic Ag deposition. Therefore, it can be applied for the highly sensitive detection of a cardiac biomarker, creatine kinase-MB.

Facile degradation of benzenediazonium-grafted thick layers on the electrode surface enabling electrochemical biosensor application.

We found that the formylbenzenediazonium (FBD)-grafted organic layers can be degraded by treating with an aqueous solution of salt and Tween. An electrochemical immunoassay was carried out on the degraded surface, which allowed highly sensitive detection of antigen mouse IgG.

An electrochemically reduced graphene oxide-based electrochemical immunosensing platform for ultrasensitive antigen detection.

We present an electrochemically reduced graphene oxide (ERGO)-based electrochemical immunosensing platform for the ultrasensitive detection of an antigen by the sandwich enzyme-linked immunosorbent assay (ELISA) protocol. Graphene oxide (GO) sheets were initially deposited on the amine-terminated benzenediazonium-modified indiun tin oxide (ITO) surfaces through both electrostatic and π-π interactions between the modified surfaces and GO. This deposition was followed by the electrochemical reduction of graphene oxide (GO) for preparing ERGO-modified ITO surfaces.

Reusable bio-functionalized surfaces based on electrochemical desorption of benzenediazonium-grafted organic layers.

We describe an electrochemical oxidative desorption of benzenediazonium-grafted organic layers and immobilized proteins on the layers from indium-tin-oxide electrode surfaces.

Aldehyde-functionalized benzenediazonium cation for multiprobe immobilization on microelectrode array surfaces.

We report in situ generation of aldehyde-functionalized benzenediazonium cation (ABD) and its use as a suitable linker molecule for fast and selective immobilization of biomolecules on indium-tin-oxide (ITO) electrode surfaces. We prepared ABD through a new reaction procedure, a simultaneous diazotation of the amine group and deprotection of the aldehyde group from an aniline derivative, 2-(4-aminophenyl)-1,3-dithiane, which was revealed on the ITO electrode surfaces through the electrodeposition of the reaction product and the characterization of the resulting surfaces with cyclic voltammetry, X-ray photoelectron spectroscopy, and protein immobilization. We also showed that successive electrodeposition of ABD and probe molecules on individually addressable microarray electrode surfaces can provide a useful platform for efficient detection of multianalyte.

Use of 1,3-dithiane combined with aryldiazonium cation for immobilization of biomolecules based on electrochemical addressing.

We report the use of 1,3-dithiane combined with aryldiazonium cation for the immobilization of biomolecules based on electrochemical addressing.