Magneto-Optic Biosensor Uses Bio-Functionalized Magnetic Nanoparticles (ANL-IN-05-122)

Researchers at Argonne National Laboratory have developed a unique magneto-optic biosensor that uses magnetic nanoparticles with biological function capability. The biosensor works when an external magnetic field and laser are applied to magnetic nanoparticles held in suspension, enabling scientists to manipulate the particles. A photodetector records the resulting light and its polarization, measuring Brownian relaxation time, which may indicate hydrodynamic radius changes upon chemical binding of the target to the magnetic nanoparticles.

Argonne’s magneto-optic biosensor can be used to measure either local rheological properties (since the Brownian relaxation time is proportional to the viscosity) or chemical binding events (which result in an increase of the hydrodynamic radius). The latter can be used as a research tool for investigating binding kinetics in real time or as a custom-designed sensor for specific target molecules. By optimizing the magnetic nanoparticle with respect to the desired target molecule, this approach can be adapted to a wide variety of targets, such as specific molecules, proteins, and disease markers. At the same time, the ability to directly investigate reaction kinetics enables researchers to examine how different chemical/biological environments influence the binding process.

• Many biological and medical uses, including targeted drug delivery, magnetic separation, hyperthermal treatment and biosensors
• Rapid, sensitive detection
• Cost-effective
• Easy to use, even by relatively untrained personnel
• Infinite shelf life

• Medical: detecting disease-causing bacteria and viruses; detect and monitor DNA hybridization, DNA/RNA-protein, protein-protein, and protein-small molecule interactions
• Pharmaceuticals: drug discovery and evaluation
• Bioterrorism and environmental: remote sensing of airborne bacteria and detecting water toxins and contaminants
• In vitro: detection of local temperature and viscoelasticity within intercellular environments
• In vivo: immunoassays