Rotating Gold Nanomotors for High-Resolution Mapping of Subcellular Nanomotions

Nanometer-scale movements (nanomotions) of living cells provide sensitive indicators of cellular state and viability, yet capturing such dynamics with nanometer precision and subcellular resolution remains a major challenge. To overcome this limitation, a light-driven nanomotor platform based on plasmonic gold nanorods is introduced, in which circularly polarized light traps and rotates individual nanorods to transduce local cellular nanomotions into measurable rotational-frequency fluctuations. The frequency-based readout achieves tunable performance, offering 10 nm axial precision at second timescales, or 130 nm precision with millisecond temporal resolution over ≈300 × 300 nm² regions of the cellular surface. Applied to human microvascular endothelial cells (HMEC-1), the method resolves heterogeneous nanomotion patterns across the nucleus, perinuclear region, and cell periphery. The measured nanomotion amplitudes greatly exceed frequency fluctuations observed on glass and fixed cells, confirming that the signals originate from active cellular processes. Transient oscillations at 10-20 Hz are detected in nuclear and perinuclear regions, revealing short-lived mechanical events that are typically inaccessible to conventional methods. Power spectral analysis further uncovers scale-invariant 1/f^α dynamics, distinguishing correlated and stochastic motion regimes. Together, these results establish a label-free and non-invasive approach for quantitative, high-resolution mapping of subcellular mechanics and dynamic processes in living cells.