- Quartz Crystal Microbalance (QCM) immunosensors are highly sensitive biosensors that combine the principles of immunoassays with acoustic sensing technology to detect biomolecular interactions in real time and without the need for labels. They operate based on the piezoelectric properties of quartz crystals, which vibrate at a specific resonant frequency when an alternating voltage is applied. Any change in the mass on the crystal surface, such as the binding of an antigen to an immobilized antibody, causes a measurable shift in this frequency.
- In a typical QCM immunosensor setup, a specific antibody is immobilized on the gold-coated surface of the quartz crystal. When a sample containing the target antigen is introduced, the antigen binds to the antibody, increasing the mass on the sensor surface. This mass change leads to a decrease in the resonant frequency of the crystal, which is directly proportional to the amount of antigen bound. The frequency shift is recorded in real time, allowing for kinetic analysis of the binding events.
- One of the key advantages of QCM immunosensors is their label-free detection, which eliminates the need for fluorescent or enzymatic tags and reduces assay complexity and time. Additionally, QCM can detect very small changes in mass—down to the nanogram or even picogram level—making it suitable for detecting low-abundance targets. It also provides insights into the binding kinetics and affinity between molecules, which is valuable for characterizing antibody-antigen interactions.
- QCM immunosensors are used in various fields, including medical diagnostics, environmental monitoring, food safety, and pharmaceutical development. For example, they can be applied to detect pathogens, toxins, hormones, or disease biomarkers. As microfabrication and surface chemistry technologies advance, QCM-based immunosensors are becoming more miniaturized, sensitive, and multiplexed, further enhancing their potential for point-of-care testing and real-time monitoring of biological processes.
