Smartphone-integrated urinary CTX-II immunosensor based on wavelength filtering from chromogenic reaction

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Optical Sensing

Background:

• Optical biosensors offer simple operation and minimal electronic components for diagnostics.
• Integrating smart IT devices with biochemical assays enhances biosensor efficacy.
• Existing methods may require complex equipment, limiting point-of-care applications.

Purpose of the Study:

• To develop a simple, smartphone-based optical biosensing system.
• To utilize a wavelength filtering principle and count-based analysis for analyte detection.
• To enable point-of-care testing (POCT) in resource-limited environments.

Main Methods:

• A smartphone-based system was designed using a paper signal guide with red patterns and a biosensing channel.
• A horseradish peroxidase (HRP)-based enzymatic reaction produced a blue product, acting as a red light absorber.
• Analyte concentration was quantified by counting the number of disappearing red patterns on the signal guide.

Main Results:

• The system successfully measured urinary C-telopeptide fragment of type II collagen (uCTX-II) concentrations (0-10 ng/mL).
• Quantitative analysis of uCTX-II in real urine samples was achieved.
• The developed optical transducing system demonstrated high sensitivity and specificity.

Conclusions:

• The developed optical biosensing system offers a simple and effective method for analyte detection.
• This technology is suitable for point-of-care testing (POCT) in resource-limited settings.
• The system provides a cost-effective and accessible diagnostic tool.