Functionalized Protein Bioelectrodes for Direct Electron Transfer

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Solution Overview

Problem

Existing biosensors face challenges in efficiently detecting multiple analytes due to the limited solubility of redox mediators in aqueous solutions, which hinders direct electron transfer (DET) between enzymes and electrodes, and the active sites of native proteins are often electrically inaccessible, making them unsuitable for practical bioelectronic applications.

Innovation Solution

Functionalization of proteins with redox-active groups in organic solvents, allowing for DET and maintaining at least 30% biocatalytic activity, enabling the use of bioconjugated proteins in biosensors, electrochemical inhibitor testing systems, and memristors, with the ability to detect multiple analytes using a single biosensor.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If redox mediators are used in aqueous solutions to facilitate electron transfer, then electron transfer efficiency is improved, but solubility of redox mediators is limited

Engineering Contradiction:
Improveelectron transfer efficiencyVSAvoidsolubility of redox mediators
Core Design Contradiction:
ReliabilityVSQuantity of substance

Solution Approach 1:

The patent changes the solvent parameter from aqueous to organic solvents (acetonitrile, dimethyl carbonate, ethyl methyl carbonate) to dissolve redox mediators that are insoluble in water, thereby achieving both high electron transfer efficiency and adequate solubility of mediators

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite system combining organic-soluble redox mediators with protein enzymes in organic solvent environments, enabling effective electron transfer while maintaining mediator solubility through the organic solvent medium

Inventive Principle:
Principle #40Composite materials

2Reliability

If native proteins are used in biosensors, then biocatalytic activity is maintained, but active sites are electrically inaccessible

Engineering Contradiction:
Improvebiocatalytic activityVSAvoidelectrical accessibility of active sites
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent introduces redox mediators as intermediary substances that shuttle electrons between the protein active sites and the electrode, making the electrically inaccessible active sites accessible for electron transfer while preserving the native protein structure and biocatalytic activity

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the local electrical environment around the protein active sites by introducing redox mediators that concentrate electron transfer capacity at the protein-solvent-electrode interface, enabling electron transfer without altering the overall protein structure

Inventive Principle:
Principle #3Local quality

3Adaptability or versatility

If proteins are functionalized in aqueous solutions, then biocompatibility is improved, but solubility of redox mediators deteriorates

Engineering Contradiction:
ImprovebiocompatibilityVSAvoidsolubility of redox mediators
Core Design Contradiction:
Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent changes the solvent parameter from water to organic solvents during the protein functionalization process, enabling dissolution of redox mediators while maintaining protein stability and functionality through careful selection of biocompatible organic solvents

Inventive Principle:
Principle #35Parameter changes

4Device complexity

If mediators are eliminated from biosensors, then fabrication complexity is reduced, but electron transfer efficiency deteriorates

Engineering Contradiction:
Improvefabrication complexityVSAvoidelectron transfer efficiency
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent enables proteins to directly transfer electrons to the electrode through self-assembly and direct electrical contact, eliminating the need for external mediators while maintaining high electron transfer efficiency through optimized protein-electrode interfaces in organic solvents

Inventive Principle:
Principle #25Self-service

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

The method allows for the production of bioelectrodes with consistent activity across varying operational conditions, enabling the detection of multiple analytes in a single sample, reducing fabrication complexity, and facilitating applications in clinical, food, and brain-computer interfaces.

Implementation Method 1

The protein functionalization technology relies on the direct electron transfer (DET) phenomenon between bioconjugated proteins and electrodes. DET is an electron transfer process where the electrons are tunnelled from the electrode to the redox cofactor of a protein

Methodology Applied
Scientific EffectDirect electron transfer (DET): Redox Reactions

Implementation Method 2

a part of the shell of the enzyme must be either stripped or modified with redox-active or semiconducting compounds that act as electron relays, making the enzyme electrically conductive

Methodology Applied
Scientific EffectRedox mediation: Redox Reactions

Data Source

PatentEP4671378A1Bioelectronics based on functionalized proteins
Publication Date: 2025.12.31 VILNIUS UNIV
  • EP4671378A1 patent drawingFigure 1
  • EP4671378A1 patent drawingFigure 2a~2b
  • EP4671378A1 patent drawingFigure 3~4a

AI summary

The invention relates to chemical, electrochemical and non-covalently bioconjugation (functionalization) of proteins with catalytic properties. A functionalization method is disclosed using all organic solvents except dimethylformamide (DMF), and dimethyl sulfoxide (DMSO), and utilizing organic synthesis and non-covalent insertion methods. Furthermore, the invention encompasses the preparation of bioelectrodes designed for the detection of substances, including but not limited to glucose, lactose, galactose (as carbohydrates), dopamine, adrenaline (epinephrine), noradrenaline (norepinephrine), and serotonin (as neurotransmitters), L-glutamate, D- or L-amino acids, hydrogen peroxide, nicotine, cholesterol, ethanol, oxalate, lactate, and pyruvate in food products, as well as in human body fluids serving as real samples. Additionally, this invention extends to the utilization of bioelectrodes for monitoring chemical processes, including features and the chemical environment of neuron interfaces within the brain. The invention encompasses an electrochemical inhibitor testing system utilizing the aforementioned bioelectrodes, and the functionalized proteins as single-molecular protein-based memristors.