Mutagenized Redox Enzyme Biosensor Interference Reduction

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Solution Overview

Problem

Existing biosensors face interference issues due to the dependence on oxygen concentration, which affects the accuracy of analyte detection, particularly for enzymes that cannot effectively utilize mediators, leading to poor stability and increased background noise.

Innovation Solution

Genetically modified redox enzymes, such as sarcosine oxidase and bilirubin oxidase, are engineered to preferentially transfer electrons to artificial mediators instead of natural electron acceptors like oxygen, reducing interference and enhancing operational stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If natural electron acceptors (oxygen) are used in enzyme-based biosensors, then the biosensor can operate in ambient conditions, but the measurement accuracy deteriorates due to interference from oxygen concentration dependence and background noise

Engineering Contradiction:

Improveoperational stabilityVSAvoidanalyte detection accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent introduces artificial electron mediators (such as ferrocene derivatives, osmium complexes, or quinone compounds) as intermediary substances between the enzyme's active site and the electrode. These mediators accept electrons from the reduced enzyme and transfer them to the electrode, replacing oxygen as the terminal electron acceptor. This intermediary system eliminates the interference caused by oxygen concentration fluctuations while maintaining continuous electron flow, thereby improving both measurement precision and operational reliability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the electrochemical parameters of the system by using mediators with specific redox potentials that are optimized for the enzyme's electron transfer capability. By selecting mediators with appropriate standard potentials (typically 0.2-0.6 V vs. Ag/AgCl), the system achieves lower operating potentials that reduce background current and interference from other electroactive species in the sample, thus improving analyte detection accuracy

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If artificial mediators are used to avoid oxygen dependence, then measurement accuracy improves, but interference from other electrochemically active substances increases

Engineering Contradiction:

Improveanalyte detection accuracyVSAvoidelectrochemical interference

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent employs mediators with moderate redox potentials that create an equipotential environment favorable for the specific enzyme-mediator-electrode system. By matching the mediator's potential to the enzyme's electron transfer characteristics, the system maximizes the enzyme-mediator reaction rate while minimizing the oxidation of interfering substances, thereby achieving high measurement precision with reduced electrochemical interference

Inventive Principle:

Principle #12Equipotentiality

3Reliability

If enzymes are engineered to transfer electrons to artificial mediators, then operational stability improves, but device complexity increases due to genetic modification requirements

Engineering Contradiction:

Improvemediator utilization efficiencyVSAvoidenzyme engineering complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies site-directed mutagenesis to modify specific amino acid residues in the enzyme's active site or electron transfer pathway. These targeted mutations (changing only a few critical residues) alter the enzyme's electron transfer preferences without requiring complete redesign of the enzyme structure, thus improving mediator utilization efficiency while minimizing the complexity increase associated with genetic modification

Inventive Principle:

Principle #35Parameter changes

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 modified enzymes enable accurate analyte detection in the presence of oxygen, reducing background noise and improving stability, allowing for precise measurement of target analytes like creatinine and bilirubin without the need for oxygen-free conditions.

Implementation Method 1

transfer electrons to the electron redox mediating molecule, and provide enzymatic activity against the target analyte to generate an electrochemical signal

Methodology Applied

Scientific EffectElectron transfer: Redox Reactions

Implementation Method 2

The transducer converts the biochemical signal into an electrical signal, which can be suitably processed and output

Methodology Applied

Scientific EffectElectrochemical transduction:

Data Source

PatentUS9562874B2Biosensor with improved interference characteristics

Publication Date: 2017.02.07 ABBOTT POINT OF CARE INC

AI summary

This invention relates to mutagenized redox oxidase enzymes used to design enzyme electrodes with improved interference characteristics in the presence of mediator and oxygen in the assay. This recombinant modified enzyme has enhanced capability to transfer electrons to redox mediator instead of its natural electron acceptors such as O2, NAD, NADP, etc., which will improve the assay performance with less interference and higher sensitivity.