Nanoengineered optical urea biosensor for estimating hemodialysis parameters in spent dialysate

Area of Science:

• Biomedical Engineering
• Optical Biosensing
• Materials Science

Background:

• Urea monitoring is critical for assessing hemodialysis efficiency.
• Existing methods for urea detection can be complex or time-consuming.
• Development of rapid, sensitive, and cost-effective biosensors is needed.

Purpose of the Study:

• To develop and validate an optical biosensor for sensitive urea detection.
• To utilize urease-encapsulated alginate microspheres with cresol red dye as an optical transducer.
• To assess the biosensor's performance in measuring urea concentrations in spent dialysate fluid.

Main Methods:

• Layer-by-layer (LbL) self-assembly for polyelectrolyte nanofilm deposition.
• Encapsulation of urease within calcium alginate microspheres.
• Flow-through cell coupled with a fiber optic spectrometer for real-time monitoring.
• Measurement of pH change and absorbance ratio for urea quantification.

Main Results:

• The optical biosensor demonstrated pH reversibility and high sensitivity (0.09 pH units/min).
• Detection limit for urea was as low as 0.1 mg/dL, with a broad detection range (0.1-60 mg/dL).
• Sensor response time was 8 minutes, suitable for clinical applications.
• Analysis of biological samples showed excellent agreement with a reference method (95% confidence level).

Conclusions:

• The developed optical biosensor offers a reliable and sensitive method for urea quantification.
• This technology has potential applications in monitoring hemodialysis and other clinical diagnostics.
• The use of LbL-assembled cresol red dye films provides an effective optical transduction mechanism.