Long‐Term Bio‐Spin Readouts Enable Decoding Immune‐Imposed Stress at the Single‐Cell Level

Electronic spin dynamics represent a fundamentally important yet largely unexplored state parameter of living cells, offering stable sensitivity to intracellular paramagnetic environments associated with cellular stress responses. However, how immune-imposed intracellular stress evolves over time and relates to divergent single-cell outcomes remains unclear, owing to the lack of continuous and nonconsumptive readouts. Here, we establish a long-term bio-spin readout based on nanodiamonds hosting nitrogen-vacancy centers as inheritable intracellular spin reporters, enabling continuous spin relaxometry in living cells. By integrating population-level ROS-associated paramagnetic stress profiling with long-term single-cell tracking in Hela and A549 cancer cells during coculture with activated macrophages, we identify three characteristic oxidative-stress trajectory patterns-remote immune stress, immune evasion, and apoptosis-whose distinct temporal dynamics cannot be resolved by endpoint assays alone. Longitudinal bio-spin measurements reveal that immune pressure is encoded not only by instantaneous oxidative levels but also by the temporal accumulation and regulation of intracellular stress. An empirical bio-spin transition range provides an operational reference for distinguishing recoverable stress responses from apoptosis-associated trajectories, while characteristic completion times capture the interaction- and cell-type-dependent kinetics of stress evolution. Together, this work establishes bio-spin dynamics for resolving immune-imposed stress histories and their associations with divergent cellular outcomes in living systems.