Serum cholinesterase assay using a reagent-free micro pH-stat

Area of Science:

• Biochemistry
• Analytical Chemistry
• Biomedical Engineering

Background:

• Enzyme activities in body fluids serve as crucial diagnostic markers for various physiological conditions and diseases.
• Conventional enzyme assays often rely on optical methods, necessitating the use of pseudosubstrates and dyes, which can complicate analysis.

Purpose of the Study:

• To introduce a novel reagent-free micro pH-stat system for the absolute determination of enzyme activity.
• To eliminate the need for exogenous reagents in enzyme assays.
• To develop a miniaturized device for potential point-of-care testing applications.

Main Methods:

• The micro pH-stat utilizes electrolysis for precise dosing of acid or base titrant to maintain a stable sample pH.
• The system is integrated with the rotating sample system (RSS), a microfluidic platform designed for handling microliter-volume samples.
• Enzyme activity was measured by analyzing serum cholinesterase levels in both fetal bovine serum and human serum samples.

Main Results:

• The reagent-free micro pH-stat accurately determined absolute enzyme activity without requiring additional reagents.
• Performance evaluation showed high comparability with standard enzyme assay techniques, evidenced by a high coefficient of determination (r²=0.99).
• The developed system demonstrated a broader detection range compared to conventional methods.

Conclusions:

• The reagent-free micro pH-stat represents a significant advancement in enzyme activity measurement, offering a simpler and potentially more versatile alternative.
• This technology has the potential for development into a miniaturized, portable device suitable for point-of-care diagnostic applications.
• The elimination of reagents simplifies the assay process and reduces potential sources of error.