Easily Fabricated Microfluidic Devices Using Permanent Marker Inks for Enzyme Assays.

Area of Science:

• Analytical Chemistry
• Biochemistry
• Materials Science

Background:

• Microfluidic paper analytical devices (μPADs) offer a low-cost platform for diagnostics.
• Colorimetric detection methods are valuable for simple analyte quantification.
• Enzyme-based assays provide high specificity for target molecules.

Purpose of the Study:

• To develop an inexpensive and rapid method for fabricating μPADs.
• To create a colorimetric assay for glucose detection using readily available materials.
• To demonstrate the utility of permanent markers in defining fluidic pathways on paper.

Main Methods:

• Fabrication of μPADs by drawing hydrophobic barriers with permanent markers on chromatography paper.
• Immobilization of glucose oxidase (GOx), horseradish peroxidase (HRP), and potassium iodide (KI) on the μPADs.
• Colorimetric detection of glucose based on the enzymatic oxidation of iodide to iodine, producing a color change.

Main Results:

• Successfully fabricated μPADs using permanent marker ink for defining hydrophilic flow paths.
• Demonstrated a colorimetric assay for glucose detection, with a visible color change from clear to brownish-yellow.
• Two distinct paper device designs were created for independent glucose assay zones.

Conclusions:

• Permanent markers provide an inexpensive, rapid, and accessible method for fabricating μPADs.
• The developed μPADs enable colorimetric detection and quantification of glucose without specialized laboratory equipment.
• This approach simplifies the creation of paper-based analytical devices for point-of-care applications.