Confocal epifluorescence sensor with an arc-shaped aperture for slide-based PCR quantification

Area of Science:

• Biophotonics
• Molecular Diagnostics
• Sensor Technology

Background:

• Growing demand for portable diagnostics, pathogen detection, and biosecurity necessitates advanced real-time quantitative polymerase chain reaction (qPCR) sensors.
• Existing qPCR systems can be bulky and expensive, limiting their application in point-of-care settings.

Purpose of the Study:

• To develop a highly sensitive, low-cost, and compact light-emitting diode (LED)-based epifluorescence sensor module for qPCR applications.
• To demonstrate the sensor's capability for rapid DNA and PCR detection in bioassay development.

Main Methods:

• Designed a compact confocal LED epifluorescence sensor incorporating a light stop with an arc-shaped aperture, inspired by microscope dark-field detection.
• Utilized dichroic mirror-free and confocal optical characteristics for size reduction and minimal optics.
• Integrated the sensor with potential for in situ real-time PCR thermal cycling.

Main Results:

• Achieved sensitive detection of sub-ng/μL standard DNA concentrations.
• Successfully detected as few as 10^1 copies of Salmonella typhimurium InvA gene sequences from non-purified samples after 30-cycle PCR.
• Demonstrated highly sensitive and specific signal responses comparable to commercial qPCR instruments.

Conclusions:

• The developed LED-based epifluorescence sensor offers a promising, cost-effective solution for portable real-time qPCR diagnostics.
• The sensor's design facilitates integration and enhances flexibility for rapid DNA and PCR detection in various bioassay applications.
• This technology has the potential to significantly impact point-of-care diagnostics and biosecurity applications.