Poly(lactic-co-glycolic acid) for reagent storage and controlled release in thermoplastic microfluidics

Area of Science:

• Biomaterials Science
• Microfluidics
• Analytical Chemistry

Background:

• On-chip storage of dried reagents is crucial for microfluidic point-of-care (POC) devices.
• Current methods face challenges in reagent stability and controlled release.
• Developing robust reagent integration is key for advanced POC applications.

Purpose of the Study:

• To investigate poly (lactic-co-glycolic acid) (PLGA) as an encapsulant for dried reagents on microfluidic chips.
• To enable controlled release of reagents triggered by temperature changes.
• To demonstrate the feasibility of PLGA encapsulation for integrated diagnostic assays.

Main Methods:

• PLGA/ethyl acetate solution was used to create encapsulating shells for dried reagents on cyclic olefin polymer (COP) microfluidic chips.
• Reagent retention was tested under aqueous flow with varying PLGA shell thicknesses.
• Controlled reagent release was achieved by heating the chip above a threshold temperature (40 °C).
• An on-chip loop-mediated isothermal amplification (LAMP) assay for MRSA detection was implemented.

Main Results:

• PLGA encapsulation effectively isolated reagents during sample introduction at room temperature.
• Over 90% of encapsulated nucleic acids were retained with shell thicknesses below 20 μm during aqueous flow.
• Heating above 40 °C caused PLGA shrinkage, delamination, and rapid reagent release.
• Successful implementation of a multi-reagent LAMP assay for MRSA detection was demonstrated.

Conclusions:

• PLGA serves as a simple and effective encapsulant for on-chip storage and controlled release of dried reagents.
• This technique enhances the manufacturing of reagent-integrated microfluidic devices.
• It paves the way for developing true sample-in, answer-out POC diagnostic systems.