Magnetoresistive Biosensors for Quantitative Proteomics

Protein detection and quantification is routinely performed in laboratories around the world for in-vitro diagnostics. Many different sensing platforms, such as mass spectrometry, optical biosensors, electrochemical biosensors, magnetic biosensors, etc., have been developed for quantitatively detection. The sandwich immunoassay is widely used as a labeled detection method due to its high specificity and flexibility allowing multiple different labels. While optical sensors use enzyme and fluorophore labels to detect proteins with high sensitivity, they often suffer from high background signal and present challenges in miniaturization. Magnetic biosensors, including nuclear magnetic resonance sensors, oscillator-based sensors, Hall-effect sensors, and magnetoresistive sensors, use the specific binding events between magnetic nanoparticles (MNPs) and target proteins to measure the analyte concentration. Compared with other biosensing techniques, magnetic sensors take advantage of the intrinsic lack of magnetic background in biological samples to achieve high sensitivity and high specificity, and are compatible with semiconductor-based fabrication processes to enable low-cost and small-size devices for point-of-care (POC) applications. Although still in development, magnetic biosensing is a promising technique for in-home testing and portable disease monitoring.