Multi-day single-cell magnetic imaging of living cancer cells using Quantum Cell Monitoring

Abstract

Live-cell imaging of cellular and tissue samples relies predominantly on optical modalities, such as fluorescence, confocal, and multiphoton microscopy, in which cellular information is encoded in emitted photons. Photons scatter and attenuate in biological samples, restricting depth resolution, while the excitation light required to produce them induces photodamage that perturbs the very biology under observation. Magnetic fields, by contrast, traverse biological samples without attenuation at cellular length scales, but the imaging modality that extracts the encoded information, magnetic resonance imaging, cannot resolve individual cells. Here we present Quantum Cell Monitoring (QCM), a widefield nitrogen-vacancy magnetometry platform that encodes single-cell information in stray magnetic fields rather than emitted photons and reads it out at subcellular resolution. Integrated with a specialized live-cell incubator, QCM tracks magnetically labeled living cancer for up to 72 h through their individual magnetic field signatures. It captures single-cell mitosis and morphological remodeling, as well as cell cluster formation, splitting, and migration even within dense regions where brightfield contrast collapses. By shifting the carrier of single-cell information from propagating optical photons to static magnetic stray fields, QCM decouples cell from cellular optical accessibility and auto-fluorescence, enabling sustained live-cell observation in regimes inaccessible to optical microscopy.