Pentacyanoammineferrate-Based Non-Enzymatic Electrochemical Biosensing Platform for Selective Uric Acid Measurement.

The electrochemical-based detection of uric acid (UA) is widely used for diagnostic purposes. However, various interfering species such as ascorbic acid, dopamine, and glucose can affect electrochemical signals, and hence there is an outstanding need to develop improved sensing platforms to detect UA with high selectivity. Herein, we report a pentagonal mediator-based non-enzymatic electrochemical biosensing platform to selectively measure UA in the presence of interfering species.

Two-Ply Carbon Nanotube Fiber-Typed Enzymatic Biofuel Cell Implanted in Mice.

Implantable devices have emerged as a promising industry. It is inevitable that these devices will require a power source to operate in vivo. Thus, to power implantable medical devices, biofuel cells (BFCs) that generate electricity using glucose without an external power supply have been considered.

Motility enhancement of human spermatozoa using electrical stimulation in the nano-Ampere range with enzymatic biofuel cells.

Sperm motility is a crucial factor for normal fertilisation that is partly supported by mitochondrial activity. Enzymatic biofuel cells (EBFCs) generate electric currents by an electron grade from anodic to cathodic electrodes in a culture media. We demonstrate that electrical stimulation by EBFC at the nano-Ampere range enhances sperm motility that can potentially allow the development of a new therapeutic tool for male infertility, including poor motility.

Performance of a glucose-reactive enzyme-based biofuel cell system for biomedical applications.

A glucose-reactive enzyme-based biofuel cell system (EBFC) was recently introduced in the scientific community for biomedical applications, such as implantable artificial organs and biosensors for drug delivery. Upon direct contact with tissues or organs, an implanted EBFC can exert effects that damage or stimulate intact tissue due to its byproducts or generated electrical cues, which have not been investigated in detail. Here, we perform a fundamental cell culture study using a glucose dehydrogenase (GDH) as an anode enzyme and bilirubin oxidase (BOD) as a cathode enzyme.

Stretchable Fiber Biofuel Cell by Rewrapping Multiwalled Carbon Nanotube Sheets.

The fiber-type biofuel cell is attractive as an implantable energy source because the fiber can modify various structures and the wound can be stitched like a suture. In addition, in daily life, the biofuel cell is forced by human motion, and stretchability is a critical requirement for real applications. Therefore, we introduce a new type of highly stretchable, stable, soft fiber biofuel cell with microdiameter dimensions as an energy harvester.

Ultrasonic synthesis and characterization of poly(acrylamide)-co-poly(vinylimidazole)@MWCNTs composite for use as an electrochemical material.

Applying a nanocomposite to increase the conductivity of an electrode can facilitate electrochemical analysis. In this regard, multi-walled carbon nanotubes (MWCNTs) evenly dispersed in hydrophilic solution can play an important role in electrochemical bio-sensing due to their unique properties, such as their high electrical conductivity and ability to conjugate with hydrophilic enzymes. Herein, we report the simple ultrasonic synthesis of a highly dispersible, enzyme-binding nanocomposite, poly(acrylamide)-co-poly(vinyl imidazole) (7:1 mol ratio)-MWCNTs (PAA-PVI@MWCNTs).

A Simple Interfacial Platform for Homogeneous Electrochemical Immunoassays Using a Poly(Vinylimidazole)-Modified Electrode.

In this study, a homogeneous method featuring simple, one-step detection was developed to analyze hippuric acid (HA), a major metabolite of toluene. High sensitivity was achieved with the facile immobilization of poly(vinylimidazole) (PVI) on an indium tin oxide (ITO) electrode. Using a previously developed approach, pentacyanoferrate was coordinated with pyridyl- ligands, and the redox-active Fe(II/III) centers were bound to Ni(II) ions on the electrode via electrostatic cyanide bridges.

Disposable Non-Enzymatic Glucose Sensors Using Screen-Printed Nickel/Carbon Composites on Indium Tin Oxide Electrodes.

Disposable screen-printed nickel/carbon composites on indium tin oxide (ITO) electrodes (DSPNCE) were developed for the detection of glucose without enzymes. The DSPNCE were prepared by screen-printing the ITO substrate with a 50 wt% nickel/carbon composite, followed by curing at 400 °C for 30 min. The redox couple of Ni(OH)₂/NiOOH was deposited on the surface of the electrodes via cyclic voltammetry (CV), scanning from 0-1.

Electrical stimulation by enzymatic biofuel cell to promote proliferation, migration and differentiation of muscle precursor cells.

Electrical stimulation is a very important biophysical cue for skeletal muscle maintenance and myotube formation. The absence of electrical signals from motor neurons causes denervated muscles to atrophy. Herein, we investigate for the first time the utility of an enzymatic biofuel cell (EBFC) as a promising means for mimicking native electrical stimulation.

Heterogeneous electrochemical immunoassay of hippuric acid on the electrodeposited organic films.

By directly coordinating hippuric acid (HA) to the ferrate (Fe) as an electron transfer mediator, we synthesized a Fe-HA complex, which shows a good electrochemical signal and thus enables the electrochemical immunoanalysis for HA. We electrodeposited organic films containing imidazole groups on the electrode surface and then bonded Ni ion (positive charge) to induce immobilization of Fe-HA (negative charge) through the electrostatic interaction. The heterogeneous competitive immunoassay system relies on the interaction between immobilized Fe-HA antigen conjugate and free HA antigen to its antibody (anti-HA).

High-power biofuel cell textiles from woven biscrolled carbon nanotube yarns.

Biofuel cells that generate electricity from glucose in blood are promising for powering implantable biomedical devices. Immobilizing interconnected enzyme and redox mediator in a highly conducting, porous electrode maximizes their interaction with the electrolyte and minimizes diffusion distances for fuel and oxidant, thereby enhancing power density. Here we report that our separator-free carbon nanotube yarn biofuel cells provide an open-circuit voltage of 0.

Homogeneous electrochemical detection of hippuric acid in urine based on the osmium-antigen conjugate.

A homogeneous electrochemical immunoassay is based on the interaction of osmium-antigen conjugate with its antibody. The novelty presented herein is the direct conjugation of the osmium complex to a small antigen and the application of the quantitative analysis of the antigen and its antibody as the electrical signal for homogeneous immunoassay. The small antigen chosen is hippuric acid (HA), a major urinary metabolite in toluene-exposed humans.

Immunochromatographic analysis of hippuric acid in urine.

Toluene, a clear, colorless liquid with a distinctive smell, is the most commonly used industrial organic solvent. The adverse effects of chronic toluene exposure have been reported. The abuse of volatile substances is practiced mainly by adolescents and young adults.

Hydrodynamic fabrication of polymeric barcoded strips as components for parallel bio-analysis and programmable microactuation.

In this paper, we report a novel technique for the manufacture of polymeric barcoded strips having diverse characteristics such as biocatalyst-based sensing and pH-responsive actuation. The fabrication involves the use of both a microfluidic platform and in-situ photopolymerization. It is expected that this method, which is a very simple, cost-effective, and environment-friendly means for mass production, will facilitate the stable immobilization of diverse biological substances such as enzymes, DNA, and antigens.

Bilirubin oxidase label for an enzyme-linked affinity assay with O2 as substrate in a neutral pH NACL solution.

Laccase, a copper enzyme catalyzing the four-electron reduction of O(2) to water, has been shown by others to be a useful label in enzyme-linked immunoassays, in which the substrate is ambient O(2) instead of an added chemical, such as hydrogen peroxide, or a phosphate ester of a phenol. Laccase-catalyzed O(2) reduction is, however, inhibited by halides, which complex the enzyme's copper ions. Replacement of laccase by bilirubin oxidase, a copper enzyme retaining its maximal activity at high chloride concentrations and at pH 7.

Enzyme-amplified amperometric detection of 3000 copies of DNA in a 10-microL droplet at 0.5 fM concentration.

We reported earlier the detection of a 38-base DNA strand at 20 pM concentration by an enzyme-amplified sandwich-type amperometric assay. The assay utilized a carbon electrode on which a redox polymer, comprising a DNA capture sequence, was electrodeposited. When present in the tested solution, part of the probed sequence hybridized with the capture probe.

Simple enzyme-amplified amperometric detection of a 38-base oligonucleotide at 20 pmol L(-1) concentration in a 30- microL droplet.

A 38-base DNA sequence has been detected at 20 pmol L(-1) concentration in 15-35- microL droplets by means of an electrochemical enzyme-amplified sandwich-type assay on a mass-manufacturable screen-printed carbon electrode. Formation of the sandwich brought the horseradish peroxidase-label of the detection sequence into electrical contact with a pre-electrodeposited redox polymer, making the sandwich an electrocatalyst for the reduction of hydrogen peroxide to water at +0.2 V (Ag/AgCl).

An oxygen cathode operating in a physiological solution.

We report the electroreduction of O(2) to water under physiological conditions (pH 7.4, 0.15 M NaCl, 37.