Rapid, Ultra-Sensitive, PCR-Free Detection Method Makes Genetic Analysis More Accessible

By LabMedica International staff writers
Posted on 22 Apr 2025

Image: Light accelerates DNA hybridization using gold nanoparticles and polystyrene microparticles as probes for PCR-free DNA detection (Photo courtesy of Osaka Metropolitan University)

Genetic testing has been an important method for detecting infectious diseases, diagnosing early-stage cancer, ensuring food safety, and analyzing environmental DNA. For a long time, polymerase chain reaction (PCR) has been the gold standard for analyzing DNA changes. With the onset of the COVID-19 pandemic, the term "PCR" became widely recognized. However, PCR tests are expensive, time-consuming, and require specialized lab equipment and trained personnel. While PCR-based genetic testing gained significant attention during the pandemic, light-based methods are now offering a PCR-free alternative for genetic analysis.

Researchers at Osaka Metropolitan University (Osaka, Japan) have developed a groundbreaking light-induced DNA detection method that employs heterogeneous probe particles. This innovative technique enables highly sensitive and rapid genetic analysis without the need for PCR amplification. This advance promises to make genetic testing faster, more affordable, and more precise, benefiting fields like medicine, environmental science, and portable diagnostics. Unlike PCR, which amplifies DNA sequences by creating millions of copies for detection, this new approach directly identifies DNA by concentrating it and enhancing its specificity through optical forces and the photothermal effect. In their study, published in ACS Sensors, the researchers used heterogeneous probe particles, including gold nanoparticles and polystyrene microparticles, to create a detection system. These probes are short DNA sequences that are designed to bind with complementary sequences in the target DNA.

This process, known as DNA hybridization, results in the formation of detectable DNA pairs through fluorescence. The solution containing the target DNA and probe particles was then irradiated with laser light. When the particle size aligns with the laser wavelength, a phenomenon called Mie scattering occurs, which generates optical forces that move the particles and speed up DNA hybridization. The gold nanoparticles absorb the laser light, producing localized heat, also known as the photothermal effect, which further enhances the specificity of the hybridization. By eliminating the need for PCR amplification, this method reduces both the cost and complexity of genetic testing while delivering faster results. This innovation has the potential to make genetic analysis more accessible, with wide-ranging applications in healthcare and personal health tracking.

“Our light-induced method detects DNA without the need for PCR,” wrote the study’s lead authors. “Using just about five minutes of laser light irradiation, our method demonstrated great potential for accurate mutation detection with a sensitivity one order of magnitude higher than that of digital PCR. 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.”

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Osaka Metropolitan University