Miniaturization of a colorimetric cellulase activity assay on a microfluidic sensor platform

Area of Science:

• Biotechnology
• Analytical Chemistry
• Materials Science

Background:

• Enzymes are critical industrial catalysts and reagents, with biological activity being a key quality attribute.
• Current enzyme activity assays are often laborious and difficult to adapt for on-site, mobile microfluidic devices.
• Cellulase activity monitoring is essential for enzyme production quality control.

Purpose of the Study:

• To integrate a colorimetric cellulase activity assay onto a microfluidic sensor platform.
• To develop a chip-amenable readout method for enzyme activity and substrate solubilization.
• To optimize critical parameters for microfluidic enzyme assay integration.

Main Methods:

• Developed a microfluidic sensor on cyclic olefin copolymer foil using roll-to-roll processing.
• Utilized a resorufin dye release assay based on a β-cellobioside substrate.
• Optimized substrate and dimethylsulfoxide co-solvent concentrations due to solubility and activity loss issues.
• Implemented CIELAB color space image analysis for quantitative readout.
• Compared microfluidic chip assay with conventional microwell plate assays.

Main Results:

• Successfully integrated a cellulase activity assay onto a flexible microfluidic platform.
• Developed a colorimetric readout method quantifying both enzyme activity and substrate solubilization.
• Identified and optimized critical parameters for microfluidic assay performance.
• Demonstrated comparable results between microfluidic and microwell plate assays.
• Showcased the potential for on-site, facile enzyme activity monitoring.

Conclusions:

• Microfluidic integration of enzyme activity assays is feasible and offers advantages for on-site monitoring.
• The developed colorimetric readout and optimization strategy are broadly applicable to other enzyme assays.
• This work advances the development of portable analytical devices for enzyme quality control.