Light-powered DNA detection removes the need for PCR

Scientists at Osaka Metropolitan University’s Research Institute for Light-induced Acceleration System (RILACS) have used heterogeneous probe particles to develop a light-induced DNA detection technique, which enables ultra-sensitive and ultra-fast genetic analysis without the need for PCR amplification. Their advancement, which has been published in the journal ACS Sensors, is now lighting the way for fast, affordable and precise genetic analysis across medicine, environmental science and portable diagnostics.

As a means of analysing changes in DNA, genetic testing — which is essential for diagnosing infectious diseases, detecting early-stage cancer, verifying food safety, and analysing environmental DNA — has long relied on PCR (polymerase chain reaction) as the gold standard. But PCR tests are neither cheap nor fast; they typically require centralised labs, bulky equipment, and specially trained personnel.

Unlike PCR, which amplifies DNA sequences by making millions of copies of target DNA for detection, the new light-induced method directly detects DNA by concentrating it and enhancing specificity through strong optical forces and the photothermal effect. PCR amplification is therefore not required.

The research team developed a system using heterogeneous probe particles, including gold nanoparticles and polystyrene microparticles. These probes are short, known DNA sequences designed to hybridise, or bind, with complementary sequences in the target DNA. This process, known as DNA hybridisation, allows the matching strands to bind together, making the pairing detectable through fluorescence.

The researchers then irradiated with laser light the solution containing the target DNA and probe particles. When the particle size matches the laser wavelength, a phenomenon called Mie scattering occurs, generating optical forces that move the particles and accelerate DNA hybridisation. The gold nanoparticles absorb laser light, creating localised heat, or photothermal effect, to further enhance the hybridisation specificity.

According to the researchers, just five minutes of laser light irradiation demonstrates that the method’s great potential for accurate mutation detection with a sensitivity one order of magnitude higher than that of digital PCR. The method should thus reduce costs, simplify testing and accelerate results, making genetic analysis more accessible in everyday applications — from health care and food safety to environmental conservation and personal health tracking.

“We aim to apply this PCR-free technology to high-sensitivity cancer diagnostics, quantum life science research, and even at-home or environmental DNA testing,” said RILACS Director Takuya Iida.

Image has been cropped from the original and is courtesy of the study authors under CC BY 4.0