Development of colorimetric PEG-based hydrogel sensors for urea detection

Area of Science:

• Materials Science
• Biomedical Engineering
• Analytical Chemistry

Background:

• Urea is vital in environmental, agricultural, and clinical contexts, appearing in bodily fluids like blood and sweat.
• Monitoring urea levels is crucial for early detection of health issues, including kidney and liver malfunctions.
• Existing detection methods may lack the simplicity or accessibility required for widespread monitoring.

Purpose of the Study:

• To develop novel semi-interpenetrating network (semi-IPN) poly(ethylene glycol) (PEG) based hydrogels for urea sensing.
• To establish a colorimetric method for urea detection using a urease/phenol red assay.
• To evaluate the hydrogel sensors' performance for detecting urea in artificial sweat samples.

Main Methods:

• Synthesized PEG-based hydrogels (PEG700-DA/PEGx) via photo-induced free radical polymerization with polymerisation-induced phase separation (PIPS).
• Employed the urease/phenol red assay for colorimetric urea detection, observing color shifts due to pH changes.
• Characterized hydrogel properties and performed stability and kinetic studies of urease interactions.

Main Results:

• Successfully developed PEG-based hydrogels as colorimetric urea sensors.
• Achieved naked-eye detection of urea in model sweat down to 0.3 mM.
• Preliminary smartphone-based RGB quantification showed a limit of detection (LOD) of 0.8 mM and a limit of quantification (LOQ) of 2.7 mM in the green channel.

Conclusions:

• PEG-based hydrogels are effective for the colorimetric detection of urea.
• The developed sensor system demonstrates potential for simple, visual monitoring of urea levels in sweat.
• Further development using smartphone integration could enable quantitative urea analysis.