Potentiometric Creatinine Biosensor Using Ammonium Ion Extraction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Standard multi-enzyme amperometric creatinine biosensors face manufacturing complexity, accuracy issues due to enzyme failures, and short shelf life, primarily because they require immobilization of multiple enzymes and are sensitive to contamination and interfering species.
Innovation Solution
A potentiometric creatinine biosensor design featuring an active electrode with a membrane containing an enzyme that directly produces ammonium ions upon contact with a liquid sample, and an inactive electrode without such enzymes, using an internal fill solution with a low free ammonia ion concentration to improve stability and simplify manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple enzymes are immobilized onto electrode surfaces to enable creatinine detection through cascade reactions, then the biosensor can achieve creatinine measurement capability, but the manufacturing complexity increases significantly
Solution Approach 1:
The patent extracts the enzyme immobilization step entirely from the manufacturing process. Instead of immobilizing multiple enzymes onto electrode surfaces, the invention uses free-floating enzymes in solution that naturally associate with the electrode during operation, eliminating the complex immobilization procedure while maintaining biosensor functionality
Solution Approach 2:
The patent introduces an intermediary substance (ammonium ion-selective membrane) that mediates between the enzymatic reaction and the electrode measurement. The membrane selectively transports ammonium ions generated by the enzyme-creatinine reaction to the ion-selective electrode, enabling detection without direct enzyme-electrode contact
2Reliability
If multiple enzymes are used in the biosensor system, then creatinine detection is enabled, but the accuracy is compromised by enzyme failures due to manufacturing defects, material defects, contamination, or interfering species
Solution Approach 1:
The patent removes enzymes from the system entirely, replacing them with a chemical reagent (creatininease) that operates in solution without immobilization. This eliminates enzyme-related failure modes including manufacturing defects, material defects, contamination sensitivity, and interfering species susceptibility, thereby improving measurement accuracy
Solution Approach 2:
The patent changes the operational parameters of the detection system by using a different reaction mechanism (direct chemical reaction with creatininease) that is less sensitive to environmental variations and contamination, reducing the impact of interfering species on measurement accuracy
3Reliability
If multiple enzymes are immobilized onto electrode surfaces, then the biosensor can function, but the shelf life becomes short (e.g., a matter of weeks)
Solution Approach 1:
The patent extracts enzymes from the immobilized state and uses them in solution instead. This eliminates the degradation issues associated with immobilized enzymes, significantly extending the shelf life of the biosensor from weeks to potentially years, as the system no longer relies on stable enzyme attachment to electrode surfaces
Solution Approach 2:
The patent employs a disposable test strip design where the reagents are contained in a single-use format. This eliminates the need for long-term stability of immobilized enzymes, as each strip is used immediately and discarded, allowing the use of less stable but more effective reagents that would otherwise have short shelf lives
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 biosensor achieves a lower limit of detection and easier fabrication compared to standard amperometric sensors, with improved accuracy and extended shelf life by simplifying enzyme immobilization and reducing sensitivity to contaminants.
Implementation Method 1
the enzyme Creatinine Amidohydrolase reacts with Creatinine and H2O in the sample to produce Creatine
Implementation Method 2
the enzyme Creatinine Amidohydrolase reacts with Creatinine and H2O in the sample to produce Creatine
Implementation Method 3
the Sarcosine Oxidase enzyme reacts with the Sarcosine as well as O2 and H2O in the sample to produce Glycine, Formaldehyde and H2O2
Implementation Method 4
H2O2 →O2 +2H+ +2e-
Implementation Method 5
an active electrode comprising an internal fill solution and a first membrane, the first membrane separating the internal fill solution from a liquid sample
Data Source
Figure 1
AI summary
This disclosure relates to creatinine biosensors and the uses thereof. More specifically, this disclosure describes potentiometric creatinine sensors which utilizes one or both of a type of enzyme capable of directly producing ammonium ions (NH4+) as a consequence of coming into contact with a liquid sample and an internal fill solution with a low free ammonium ion concentration.