Bile acid measurements using a cholestyramine-coated TSM acoustic wave sensor

Area of Science:

• Analytical Chemistry
• Biomedical Engineering
• Materials Science

Background:

• Bile acids play crucial roles in digestion and disease.
• Accurate and real-time monitoring of bile acids is essential for diagnosis and treatment.
• Existing methods for bile acid detection can be time-consuming or lack sensitivity.

Purpose of the Study:

• To develop and characterize a novel chemical sensor for the real-time detection of bile acids.
• To evaluate the sensor's performance, including sensitivity, detection limits, and reusability.
• To investigate the binding interactions influencing bile acid detection.

Main Methods:

• Utilized a 10-MHz piezoelectric crystal in thickness-shear mode (TSM).
• Coated the crystal with cholestyramine resin for selective bile acid binding.
• Employed a batch-mode sensor block for real-time frequency monitoring upon sample injection.

Main Results:

• Achieved >90% binding completion within 10 minutes, with most binding in the first minute.
• Demonstrated increasing sensitivity in the order: cholate ≈ glycocholate < taurocholate << taurodeoxycholate.
• Reported detection limits in water ranging from 0.2-9 nmol, with excellent reusability (>400 cycles).
• Identified hydrophobic interactions and charge density as key factors in binding, with citrate significantly reducing bile acid binding.

Conclusions:

• The developed cholestyramine-based piezoelectric sensor provides a sensitive and reusable platform for real-time bile acid detection.
• Findings suggest optimizing drug formulations by avoiding excipients like citric acid to enhance bile acid sequestration efficacy.
• This sensor technology holds promise for improved diagnostics and therapeutic monitoring of bile acid-related conditions.