Microfluidic Paper-based Analytical Devices (μPADs): Miniaturization and Enzyme Storage Studies

Area of Science:

• Analytical Chemistry
• Biotechnology
• Materials Science

Background:

• Microfluidic paper-based analytical devices (μPADs) are emerging as low-cost diagnostic tools.
• Enzyme stability and assay performance in miniaturized formats are critical for practical applications.

Purpose of the Study:

• To design and develop miniaturized μPADs for biological assays and enzyme storage.
• To evaluate the performance and stability of these devices using glucose and acetylcholinesterase assays.

Main Methods:

• Fabrication of two types of μPADs ('strip' and 'grid' designs) using wax printing on chromatographic paper.
• Assessing glucose concentration using glucose oxidase (GOx), horseradish peroxidase (HRP), and potassium iodide (KI).
• Evaluating acetylcholinesterase (AChE) activity and enzyme stability under various storage temperatures (-20, 0, 20°C) over 30 days.

Main Results:

• Miniaturized μPADs demonstrated effective glucose detection with good correlation between color intensity and glucose concentration (0.89 - 15.76% error after 7 days).
• The devices showed minimal enzyme denaturation after 30 days of storage at different temperatures.
• Both 'strip' and 'grid' μPAD designs proved effective for biological assays.

Conclusions:

• Miniaturized μPADs are promising for point-of-care diagnostics and enzyme storage.
• These devices offer a viable alternative for resource-limited regions lacking advanced materials and instrumentation.
• The developed μPADs exhibit stability and reliability for biological assays.