The analysis of nucleic acids using the polymerase chain reaction (PCR) has become a central method in biotechnology. It has been used in fields ranging from screening hereditary diseases, detecting infectious pathogens, and cancer diagnosis to forensics and food quality control.
Alternative approaches to PCR that allow a faster and simpler analysis of nucleic acid-based analytes without the need for thermocycling have been researched, such as isothermal rolling circle amplification (RCA). The deployment of DNA amplification reactions at solid surfaces holds the potential to expand the performance of DNA analytical technologies through, e.g., efficient multiplexing. In addition, surface DNA amplification reactions may open doors to other sensor modalities and assay amplification strategies suitable for detecting different analytes, including proteins that cannot be directly amplified and are typically detected by immunoassays.
In a paper published in ACS Applied Materials & Interfaces called “In situ monitoring of rolling-circle amplification on a solid support by surface plasmon resonance and optical waveguide spectroscopy” the concept of using optical biosensors to monitor RCA was demonstrated by Dr. Jakub Dostalek from the Austrian Institute of Technology and habilitant at the Department of Nanobiotechnology, with the master student Bernadette Lechner from BIMat as the lead author.
Plasmonics can be used to trap light at the nanoscale close to the sensor surface and make it propagate along the surface, e.g., through the creation of a polymer film at the interfaces. As the DNA amplification occurs at the interface through RCA, it creates such a polymer layer where the light propagates, which the sensor can monitor quantitatively.
This is a beautiful example of how nanoscale physics, polymer physics, and DNA biotechnology can come together.