Glucose Sensor Reagent with Debundled Carbon Nanotubes

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Solution Overview

Problem

The use of FAD-GDH as an enzyme in glucose sensors with CNTs can result in inconsistent direct electron transfer due to the size of CNTs, leading to reduced sensitivity and accuracy.

Innovation Solution

A reagent layer comprising glycosylated FAD-GDH, debundled single-walled carbon nanotubes, and a dispersant, such as sodium cholate or cetyltrimethylammonium bromide, is applied to the electrode, ensuring effective direct electron transfer and preventing enzyme deactivation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If multi-walled carbon nanotubes or bundled single-walled carbon nanotubes are used, then the sensor structure is simpler to manufacture, but direct electron transfer between FAD-GDH and electrode does not occur reliably

Engineering Contradiction:

Improveease of manufactureVSAvoidreliability of direct electron transfer

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent segments the carbon nanotubes into individual single-walled structures using a dispersant, separating them from bundled configurations. This segmentation allows each CNT to independently access the enzyme active center, enabling reliable direct electron transfer while maintaining manufacturing simplicity through liquid dispersion application.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dispersant acts as an intermediary substance that debundles the carbon nanotubes and facilitates their uniform distribution in the reagent layer. This intermediary enables the CNTs to properly interact with FAD-GDH active centers without requiring complex manual separation processes.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If CNTs are used without dispersant, then the reagent composition is simpler, but CNT bundling occurs reducing sensor sensitivity and accuracy

Engineering Contradiction:

Improvecomplexity of reagent compositionVSAvoidmeasurement precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent changes the physical state and distribution parameters of CNTs by introducing a dispersant that modifies their aggregation behavior. The dispersant alters the interfacial properties between CNTs and the reagent layer medium, preventing bundling and ensuring uniform distribution for accurate glucose measurement.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If FAD-GDH is used with bundled CNTs, then the enzyme-CNT interaction is insufficient, but increasing enzyme concentration increases reagent layer complexity

Engineering Contradiction:

Improveenzyme-CNT interactionVSAvoidcomplexity of reagent layer

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

By segmenting bundled CNTs into individual structures through dispersant action, the patent enables effective enzyme-CNT interaction at lower enzyme concentrations. Each debundled CNT can independently access and interact with FAD-GDH active centers, maintaining reliable electron transfer without requiring increased enzyme amounts that would complicate the reagent layer.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration enhances the sensitivity and accuracy of glucose sensors by allowing debundled single-walled carbon nanotubes to enter the active center of FAD-GDH, facilitating direct electron transfer and reducing variation in sensor quality.

Implementation Method 1

direct electron transfer between a glucose-bound enzyme and an electrode through the CNTs

Methodology Applied

Scientific EffectDirect electron transfer: Conduction (electrical)

Implementation Method 2

allowing debundled single-walled carbon nanotubes to enter the active center of FAD-GDH, facilitating direct electron transfer

Methodology Applied

Scientific EffectElectron tunneling: Conduction (electrical)

Implementation Method 3

A reagent layer comprising glycosylated FAD-GDH, debundled single-walled carbon nanotubes, and a dispersant

Methodology Applied

Scientific EffectDispersion: Dispersion (of waves)

Implementation Method 4

a dispersant, such as sodium cholate or cetyltrimethylammonium bromide, is applied to the electrode

Methodology Applied

Scientific EffectSurfactant action: Surfactant

Implementation Method 5

a flavin adenine dinucleotide glucose dehydrogenase (FAD-GDH)... the glucose (or a substrate) contained in the specimen reduces the mediator (or an electrode active material) via the enzyme

Methodology Applied

Scientific EffectEnzymatic catalysis: Enzyme

Implementation Method 6

when a predetermined voltage is applied to the electrode, the reduced mediator is oxidized by an electrochemical reaction. When the reduced mediator is oxidized, an oxidation current is generated

Methodology Applied

Scientific EffectElectrochemical reaction: Redox Reactions

Data Source

PatentEP3505626B1Reagent for glucose sensor, glucose sensor, method for manufacturing glucose sensor, and glucose measurement device

Publication Date: 2024.10.09 NATIONAL INSTITUTE OF ADVANCED INDUSTRIAL SCIENCE & TECHNOLOGY

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AI summary

A reagent used for a glucose sensor for electrochemical, quantitative determination of glucose, includes a flavin adenine dinucleotide glucose dehydrogenase, single-walled carbon nanotubes, and a dispersant.