Development of Electrodes for Measuring Blood Glucose Levels

Researchers at AIST, Techno Medica Co. Ltd., Tohoku University, Fuji Silysia Chemical Ltd. and JEOL Ltd. have developed a compact sensor that can measure blood glucose levels (glucose concentration) without removing foreign substances from blood using an electrode without precious metals.
Blood glucose levels can be measured electrochemically by detecting hydrogen peroxide (H₂O₂), which is generated when glucose is oxidized by the enzyme (glucose oxidase: GOx). The H₂O₂ decomposed at a platinum (Pt) working electrode, and relating the current is used to determine the glucose concentration. However, since the decomposition potential suitable for detecting H₂O₂ overlaps with the decomposition potential of dissolved oxygen and vitamin C (ascorbic acid) in blood, it is necessary to remove these interfering substances beforehand for accurate measurement. In conventional sensors using Pt electrodes, H₂O₂ is decomposed at a decomposition potential unaffected by dissolved oxygen, and vitamin C is often removed by a interfering substance removal membrane. In this study, a working electrode(PB/G/PSS) was developed by immobilizing Prussian Blue (PB), which reacts with H₂O₂, into graphene-coated porous silica spheres (G/PSS). This electrode was used to shift the decomposition potential of dissolved oxygen and vitamin C, thereby enabling the development of a sensor capable of measuring H₂O₂ without interference from these substances. The developed glucose sensor can measure blood glucose concentration in a wider range of 0 to 270 mg/dL, including the concentration range of fasting blood glucose (glucose concentration: 70 to 100 mg/dL). Furthermore, we have confirmed that using PB/G/PSS for both the working and reference electrodes maintained sensor performance, leading to the successful development of a precious metal-free sensor.
The newly developed glucose sensor, which does not require a mechanism for removal of interfering substances, promotes miniaturization of blood gas analyzers that can measure blood glucose and lactate levels. Demand for such analyzers has been increasing in recent years. Moreover, since the sensors do not use precious metals such as Pt, the sensor contributes to stable supply and lower manufacturing costs

Driving the Ammonia Nitrogen Recycling with "Prussian blue"

AIST Researchers and FUSO Corporation (hereinafter referred to as "FUSO") have developed a technology to recover ammonium ions (NH₄⁺) from industrial wastewater, reducing their concentration to a level suitable for discharge into sewage. Additionally, the recovered NH₄ is concentrated to a level suitable for use as a resource.

Ammonia and other nitrogen compounds are valuable substances used in fertilizers and industries, but their discharge into the environment contributes to environmental pollution. Therefore, international efforts are being made to recover and reuse nitrogen compounds within the nitrogen cycle. Ammonia in industrial wastewater exists primarily as NH₄⁺, highlighting the need for technology that can recover and recycle it so that NH₄⁺ is not wasted.

By replacing iron in Prussian blue, a blue pigment, with zinc, we previously developed a material capable of selectively adsorbing NH₄⁺, and desorbing it into a highly concentrated solution. Now, we have developed a continuous adsorption-desorption system and demonstrated its effectiveness in recovering NH₄⁺ in actual zinc plating wastewater. We are preparing to ship samples of the adsorbent soon. The domestic wastewater treatment market is currently valued at approximately 3 trillion yen, and this technology is expected to play a significant role in this market.