Designing and prototyping a novel biosensor based on a volumetric bar-chart chip for urea detection

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Biosensor Technology

Background:

• Volumetric bar-chart chips (V-chips) offer apparatus-free, visual analyte quantification.
• Current V-chips face limitations due to macromolecule instability, expensive catalysts, and process control issues, hindering development.
• A catalyst-free approach is needed to improve V-chip efficiency and accuracy.

Purpose of the Study:

• To introduce a novel, catalyst-free V-chip design for biosensing applications.
• To develop a simple and efficient method for urea detection in biological samples.
• To demonstrate the potential of this new V-chip for accurate, visual, and low-cost urea quantification.

Main Methods:

• Utilized the enzymatic reaction of urease with urea, producing bicarbonate.
• Converted bicarbonate to CO2 gas in an acidic environment, driving ink movement within the V-chip.
• Quantified urea concentration based on the visual distance of ink movement, proportional to CO2 gas pressure.

Main Results:

• The novel V-chip demonstrated a linear response range of 0 to 1000 μg ml⁻¹ for urea.
• Achieved a low detection limit of 3.6 μg ml⁻¹ in raw milk samples.
• Exhibited high recovery rates for urea in raw milk (96.5% at 100 μg ml⁻¹, 98.9% at 400 μg ml⁻¹).

Conclusions:

• The catalyst-free V-chip provides an efficient and simple path for biosensor design.
• This V-chip enables accurate, visual urea determination in real samples without requiring additional equipment.
• The developed V-chip technology holds significant potential for creating new, efficient, and cost-effective biosensors.