Magneto-nanosensors based on magnetic nanoparticle (MNP) labeling of biomolecules (such as proteins and DNA) and giant-magnetoresistive sensors used in computer hard drives have gained great interests in nanotechnology and biomedicine community. Here we will elucidate their intricate operation principles and explain the details of several killer applications of these emerging devices in precision medicine and precision health.

Substantial efforts have been made to understand the interactions between immune checkpoint receptors and their ligands targeted in immunotherapies against cancer, which is an important development in precision medicine in recent years. To carefully characterize the complete network of interactions involved and the binding affinities between their extracellular domains, an improved kinetic assay is needed to overcome limitations with surface plasmon resonance (SPR). Here we present a magneto-nanosensor platform integrated with a microfluidic chip that allows measurement of dissociation constants in the micromolar-range. High-density conjugation of magnetic nanoparticles with prey proteins allows multivalent receptor interactions with sensor-immobilized bait proteins, more closely mimicking natural receptor clustering on cells. The platform has advantages over traditional SPR in terms of insensitivity of signal responses to pH and salinity, less consumption of proteins, and better sensitivities. Using this platform, we characterized the binding affinities of the PD-1 – PD-L1/PD-L2 co-inhibitory receptor system, and discovered an unexpected interaction between the two known PD-1 ligands, PD-L1 and PD-L2.

The magneto-nanosensors are also well-suited for medical diagnostics of diseases at early stages because they possess attomolar to femtomolar sensitivities for protein biomarkers. The technology platform has been applied to in vitro diagnostics of lung cancer, prostate cancer, liver cancer, autoimmunity, radiation exposure, hepatitis, and Marijuana DUI. The magneto-nanosensors are being adapted for point of care settings, mobile health, and global health, and other precision health initiatives which will help us to lower healthcare costs and to adopt more healthy lifestyles.