A digital PCR system based on the thermal cycled chip with multi helix winding capillary

Area of Science:

• Biotechnology
• Microfluidics
• Molecular Diagnostics

Background:

• Digital PCR (dPCR) is a powerful tool for nucleic acid quantification.
• Improving temperature control in microfluidic PCR devices is crucial for reaction efficiency.
• Existing thermal cycling chip designs often suffer from temperature non-uniformity.

Purpose of the Study:

• To introduce a novel multi-helix thermal cycling chip for digital PCR.
• To investigate the impact of multi-helix designs on temperature uniformity and PCR efficiency.
• To demonstrate the application of this system for clinical sample analysis.

Main Methods:

• Fabrication of a novel polydimethylsiloxane (PDMS) based multi-helix thermal cycling chip with microchannels.
• Comparison of temperature uniformity between multi-helix and single-helix chip designs.
• Application of the optimized double-helical chip in continuous-flow digital PCR.
• Fluorescence signal analysis using a CMOS camera.
• Absolute quantification of Hepatitis B Virus (HBV) DNA in clinical serum samples.

Main Results:

• The multi-helix chip design significantly improves temperature uniformity in the renaturation zone compared to single-helix designs.
• Enhanced temperature uniformity leads to improved polymerase chain reaction efficiency, even with rapid fluid flow.
• Even-numbered helix designs (double, six, eight) show superior temperature uniformity over odd-numbered designs (single, three).
• Continuous-flow digital PCR was successfully performed without surfactants.
• Accurate absolute quantification of HBV DNA in clinical samples was achieved, validated by commercial instruments.

Conclusions:

• The novel multi-helix chip design represents a significant advancement in digital PCR thermal cycling technology.
• This chip design offers improved temperature control, leading to enhanced PCR efficiency and reliability.
• The system is suitable for sensitive and accurate quantification of clinical biomarkers, such as HBV DNA.