BUN Sensor Using Immobilized Urease and Carbonic Anhydrase
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Solution Overview
Problem
Current methods for determining urea in biological samples, such as blood and urine, are limited in sensitivity and accuracy, especially in real-time or near-real-time applications, and do not effectively utilize carbonic anhydrase to enhance urea sensing in clinical settings.
Innovation Solution
A microfabricated sensor device with immobilized urease and carbonic anhydrase enzymes on a substrate, using a plasticized polyvinyl chloride layer and a water-permeable matrix, which enhances the conversion of urea to ammonium ions for precise potentiometric detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a standard potentiometric sensor with urease is used, then the sensor can detect ammonium ions from urea conversion, but the sensitivity and accuracy of urea detection are limited
Solution Approach 1:
Carbonic anhydrase is introduced as an intermediary enzyme that mediates the conversion of bicarbonate to carbon dioxide, facilitating the overall urea detection process. This intermediary step enhances the sensitivity and accuracy of urea detection by improving the efficiency of the enzymatic reaction cascade.
Solution Approach 2:
The sensor utilizes changes in pH and carbon dioxide concentration as intermediate parameters to detect urea. By measuring these parameter changes through the enzymatic reactions, the sensor achieves higher sensitivity and accuracy in urea detection compared to direct ammonium ion measurement alone.
2Productivity
If the sensor operates in real-time or near-real-time mode, then rapid detection is achieved, but the response time and stability may be compromised
Solution Approach 1:
The sensor maintains continuous enzymatic action through the coupled reactions of urease and carbonic anhydrase, ensuring uninterrupted conversion of urea to detectable signals. This continuous operation enables real-time detection while maintaining stability through the sustained catalytic activity of the enzyme system.
Solution Approach 2:
The sensor undergoes preliminary calibration and stabilization steps before actual measurement, ensuring that the enzymatic reactions are fully activated and stable. This preliminary action prepares the sensor for rapid real-time detection while establishing stable baseline conditions.
3Measurement precision
If the sensor uses multiple enzymes and complex layers, then detection capability is enhanced, but the device complexity increases
Solution Approach 1:
Multiple functional layers containing different enzymes (urease and carbonic anhydrase) are merged into a single integrated sensor structure. This combining of multiple functional components into one unified device enhances detection capability while managing complexity through integrated design.
Solution Approach 2:
The sensor structure is designed to perform multiple functions: urea hydrolysis by urease, bicarbonate conversion by carbonic anhydrase, pH measurement, and carbon dioxide detection. This multi-functionality is achieved within a single integrated device, enhancing detection accuracy without proportionally increasing complexity.
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 solution significantly improves the sensitivity and accuracy of urea detection, reducing response time and increasing the stability and shelf-life of the sensors, making it suitable for rapid in situ measurements in clinical and point-of-care settings.
Implementation Method 1
The enzyme urease converts urea from the sample to ammonium ions
Implementation Method 2
the enzyme urease converts urea from the sample to ammonium ions
Implementation Method 3
The enzyme carbonic anhydrase (CA) has been used in a carbon dioxide (pCO2) sensor
Implementation Method 4
the bicarbonate formed by the urease reaction is converted to carbon dioxide by CA
Implementation Method 5
The electrical potential at the electrode is a logarithmic function of the ammonium concentration and thus the bulk urea concentration
Implementation Method 6
a plasticized polyvinylchloride layer containing the ammonium ionophore nonactin
Data Source
AI summary
A BUN (blood urea nitrogen) sensor containing immobilized carbonic anhydrase and immobilized urease for the in vitro detection of urea nitrogen in blood and biological samples with improved performance and precision characteristics.