Related Experiment Video
Updated: Jun 1, 2026
09:33
Imaging Approaches to Assessments of Toxicological Oxidative Stress Using Genetically-encoded Fluorogenic Sensors
Published on: February 7, 2018
H(2)O(2)-generating peroxidase electrodes as reagentless cyanide sensors
1Department of Applied Chemistry, Faculty of Technology, Tokyo University of Agriculture and Technology, Naka-cho, Koganei, Tokyo 184, Japan.
Analytical Chemistry
|May 31, 2011
Summary
New cyanide biosensors use horseradish peroxidase (HRP) adsorbed on pyrolytic graphite (PG) electrodes. These reagentless sensors detect cyanide by measuring inhibited current, offering a simple and inexpensive method.
Area of Science:
- Electrochemistry
- Biosensor Technology
- Environmental Monitoring
Background:
- Cyanide is a highly toxic pollutant requiring sensitive detection methods.
- Existing cyanide detection methods can be complex and costly.
- Development of simple, reagentless biosensors is crucial for widespread application.
Purpose of the Study:
- To develop an inexpensive, reagentless, single-electrode cyanide biosensor.
- To utilize horseradish peroxidase (HRP) immobilized on a pyrolytic graphite (PG) electrode.
- To establish a reliable method for cyanide detection based on electrochemical principles.
Main Methods:
- Adsorption of HRP onto a pyrolytic graphite (PG) electrode.
- Electrochemical reduction of dissolved oxygen to hydrogen peroxide (H(2)O(2)) at -300 mV vs Ag/AgCl.
- Measurement of transient cathodic current changes upon H(2)O(2) reduction at 0 mV.
- Quantification of cyanide concentration based on the inhibition of HRP-catalyzed H(2)O(2) reduction.
Main Results:
- The biosensor demonstrated a measurable transient current inhibited by cyanide.
- A HRP/PG electrode with saturated HRP coverage reliably determined cyanide concentrations from 10(-5) to 10(-3) M.
- An electrode with lower HRP coverage showed high sensitivity, detecting cyanide down to 2 × 10(-7) M due to kinetic control.
Conclusions:
- The developed HRP/PG electrode serves as an effective cyanide biosensor.
- The sensor's performance (reliability vs. sensitivity) can be tuned by controlling HRP coverage.
- This approach offers a promising, simple, and reagentless method for cyanide detection.
Related Concept Videos
01:26Redox Titration: Other Oxidizing and Reducing Agents
Besides iodine, other oxidizing or reducing agents can serve as titrants in redox titrations. Common oxidizing titrants include KMnO4, cerium(IV), and K2Cr2O7. The choice of oxidizing titrants depends on factors like stability, cost, analyte strength, and reaction rate between the analyte and titrant. KMnO4 is a strong oxidizing titrant that reduces from Mn(VII) to Mn(II) in a highly acidic solution, simultaneously oxidizing the analyte to a higher oxidation state. In this case, KMnO4 acts as a...
01:24Types of Reversible Electrodes
For electrode reversibility to be maintained, all the reactants and products involved in the half-reaction must be present at the electrode. There are several types of reversible electrodes (half-cells).In metal-metal-ion electrodes, a metal balances electrochemically with a solution of its own ions. Examples are Cu2+|Cu and Zn2+|Zn. Metals that react with the solvent, like group 1 and most group 2 metals, which react with water, and zinc, which reacts with aqueous acidic solutions, cannot be...
01:24Redox Reactions
Oxidation-reduction or redox reactions involve the transfer of electrons from one molecule or atom to another. When an atom gains an electron, another atom must lose an electron, meaning oxidation and reduction must occur together. Since the redox occurs in pairs, the atom that gets oxidized is also called the reducing agent or reductant, and the atom that is reduced is also called the oxidizing agent or oxidant. A straightforward way to remember the definitions of oxidation and reduction is...
01:10Aldehydes and Ketones with HCN: Cyanohydrin Formation Mechanism
Cyanohydrins are formed when cyanide nucleophiles and carbonyl compounds like aldehydes and ketones react. A strong base, the cyanide ion, catalyzes cyanohydrin formation. The ions are generated from HCN under aqueous conditions. Once the cyanide ions are generated, the first step involves the nucleophilic attack of the cyanide ions on the electrophilic carbonyl carbon. This attack shifts the π electrons from the C=O to the oxygen atom forming the alkoxide ion intermediate. The alkoxide anion...
01:10Amperometry: Overview
Amperometry is a technique commonly used to measure the concentration of specific analytes in a solution by monitoring the electric current generated during an electrochemical reaction. It involves applying a constant potential between a working electrode and a reference electrode to measure the resulting current, which is proportional to the concentration of the analyte. The Clark oxygen electrode operates based on this principle of amperometry. It consists of a cathode and an anode enclosed...
01:19Potentiometry: Types of Electrodes
Reference electrodes serve as a stable reference point for potentiometric measurements, while indicator and working electrodes react to variations in the composition of a solution.
The Standard Hydrogen Electrode (SHE) is a widely used reference electrode that maintains zero potential across all temperatures. However, its need for a continuous hydrogen gas supply renders it impractical for everyday use.
An alternative to SHE is the Saturated Calomel Electrode (SCE). This electrode features an...
The Standard Hydrogen Electrode (SHE) is a widely used reference electrode that maintains zero potential across all temperatures. However, its need for a continuous hydrogen gas supply renders it impractical for everyday use.
An alternative to SHE is the Saturated Calomel Electrode (SCE). This electrode features an...