Chinese researchers have unveiled a new light-based sensor capable of detecting cancer biomarkers in blood at extremely low concentrations, potentially paving the way for earlier disease detection and more effective treatment monitoring.
The sensor, developed by a team at Shenzhen University led by Han Zhang, utilizes a combination of DNA nanostructures, quantum dots, and CRISPR gene editing technology to identify faint biomarker signals using a process called second harmonic generation (SHG). Published in the journal Optica, the research demonstrates the sensor’s ability to detect lung cancer biomarkers from patient samples at sub-attomolar levels – a sensitivity achieved even when only a few biomarker molecules were present.
Currently, detecting biomarkers often requires amplification techniques, which can be both time-consuming and expensive. The Shenzhen University team aimed to create a direct sensing approach that could identify low-concentration biomarkers without these complex amplification steps, according to the published research.
The sensor’s foundation lies in SHG, an optical process where incoming light is converted to light at half its original wavelength. This occurs at the surface of molybdenum disulfide (MoS₂), a two-dimensional semiconducting material. Researchers employed DNA tetrahedrons – pyramid-like nanostructures built entirely from DNA – to precisely position quantum dots near the MoS₂ surface. These quantum dots enhance the SHG signal.
CRISPR-Cas gene editing technology is then used to identify specific biomarkers. When the Cas12a protein recognizes a target biomarker, it cleaves the DNA holding the quantum dots, resulting in a measurable decrease in the SHG signal. The minimal background noise inherent in SHG allows for the detection of even extremely low biomarker concentrations.
“Instead of viewing DNA only as a biological substance, we apply it as programmable building blocks, allowing us to assemble the components of our sensor with nanometer-level precision,” Zhang said in a statement accompanying the publication. “By combining optical nonlinear sensing, which effectively minimizes background noise, with an amplification-free design, our method offers a distinct balance of speed and precision.”
The sensor was tested using miR-21, a microRNA biomarker associated with lung cancer. Researchers successfully detected the biomarker in both a buffer solution and in human serum from lung cancer patients, simulating a real-world blood test. The sensor demonstrated high specificity, accurately identifying the lung cancer target while ignoring similar RNA strands.
According to the National Cancer Institute, biomarker tests can reveal important details about a person’s cancer, including whether It’s likely to grow and spread, which treatments are likely to be effective, and whether a treatment is working. However, current biomarker testing often requires samples of both cancer cells and healthy cells for comparison.
Zhang’s team is now focused on miniaturizing the optical setup, with the goal of creating a portable device suitable for use at the point of care, in clinics, or in remote locations with limited resources. The researchers envision a future where simple blood screenings could detect lung cancer before tumors are visible on traditional CT scans, and where daily or weekly biomarker monitoring could aid doctors assess drug efficacy more rapidly than current imaging-based methods allow.