Engineered MagLOV proteins enable in vivo quantum sensing with MRI-like imaging

Researchers engineered magneto-sensitive fluorescent proteins (MagLOV) that show optically detected magnetic resonance in living cells at room temperature, with single-cell sensitivity and ~10% ODMR contrast. Through directed evolution, variants with tunable magnetic-field responses were created, supporting multiplexed readout, lock-in detection, and spatial localization of fluorescence using magnetic-field gradients (fluorescence MRI). MagLOV reports are also sensitive to the local spin environment (e.g., gadolinium), enabling in situ sensing of cellular microenvironments. Collectively, this work demonstrates a programmable, endogenously expressible quantum-sensing platform in biology with broad imaging and sensing applications.