Fast and sensitive medical diagnostic protocol based on integrating circular current lines for magnetic washing and optical detection of fluorescent magnetic nanobeads

• A sensing platform for rapid and sensitive medical diagnostics is proposed.
• The platform incorporates circular current lines to reduce non-specific binding.
• The use of fluorescent magnetic nanoparticles avoids magnetic noise.

Magnetic nanoparticles (MNPs) are increasingly being used as ‘magnetic labels’ in medical diagnostics. Practical applications of MNPs necessitate reducing their non-specific interactions with sensor surfaces that result in noise in measurements. Here we describe the design and implementation of a sensing platform that incorporates circular shaped current lines that reduce non-specific binding by enabling the “magnetic washing” of loosely attached MNPs attached to the senor surface. Generating magnetic fields by passing electrical currents through the circular shaped current lines enabled the capture and collection of fluorescent MNPs that was more efficient and effective than straight current lines reported to-date. The use of fluorescent MNPs allows their optical detection rather than with widely used magnetoresistive sensors. As a result our approach is not affected by magnetic noise due to the flow of currents. Our design is expected to improve the speed, accuracy, and sensitivity of MNPs based medical diagnostics.