Polymer microfluidic chips with integrated waveguides for reading microarrays.

Area of Science:

• Biotechnology
• Materials Science
• Genetics

Background:

• Microfluidic devices offer miniaturized platforms for biological assays.
• Integrated optical waveguides can enhance detection sensitivity in microfluidic systems.
• Accurate detection of low-abundance DNA mutations is crucial for early disease diagnosis.

Purpose of the Study:

• To develop and demonstrate a microfluidic chip with an integrated planar waveguide for DNA analysis.
• To detect low-abundance point mutations in BRCA1 genes associated with breast cancer.
• To evaluate the sensitivity and performance of the developed system.

Main Methods:

• Fabrication of a poly(methyl methacrylate) (PMMA) microfluidic chip with a hot-embossing technique.
• Covalent attachment of DNA probes to the waveguide surface via plasma activation and carbodiimide chemistry.
• Detection of hybridization events using evanescent excitation and an imaging microscope.
• Analysis of BRCA1 gene mutations using an allele-specific ligation assay coupled with polymerase chain reaction (PCR) and ligation detection reactions (LDRs).

Main Results:

• The microfluidic/waveguide assembly enabled imaging of the entire array without scanning, offering high spatial resolution and a large field-of-view.
• Successful detection of insertion C mutations in BRCA1 genes was achieved.
• The system demonstrated the ability to detect polymorphisms present at less than 1% of the total DNA content.

Conclusions:

• The integrated microfluidic/waveguide system provides a sensitive platform for detecting low-abundance DNA mutations.
• This technology holds promise for applications in genetic analysis and early disease diagnostics, such as breast cancer screening.
• The single-step fabrication and efficient detection mechanism offer a robust solution for point-of-care genetic testing.