arXiv Preprint Shows Computational Feasibility of Amplitude-Modulated Ultrasound with Phase-Locked ODT for Separate Nuclear-Cytoplasmic Stiffness Mapping in MDA-MB-231 Cells

Researchers constructed a viscoelastic finite-element simulation of MDA-MB-231 cells driven by megahertz ultrasound amplitude-modulated at 10 Hz, then forward-modeled refractive-index changes through 100-angle holography with realistic camera noise before tomographic reconstruction. The pipeline recovered imposed stiffening trajectories after averaging four acquisitions and generated synthetic first-harmonic amplitude and phase maps that distinguish nuclear from cytoplasmic viscoelasticity. Initial experimental tomograms from five adherent cells yielded mean amplitude ratio 0.616 ± 0.098 and relative phase −1.91 ± 0.58°, both directions matching selected model scenarios.

The contact-free approach sidesteps micropipette or AFM indentation artifacts that can alter cortical tension and nuclear lamina integrity. Because nuclear mechanics influence lamin mutations and chromatin organization in cancer metastasis, a method that reports regional dissipation separately from stiffness could accelerate mechanopharmacology screens for drugs targeting nuclear envelope proteins. Existing Brillouin microscopy provides label-free stiffness maps yet remains diffraction-limited for deep nuclear contrast and lacks independent phase information on viscous losses.

The five-cell cohort and absence of calibrated phase-noise measurements preclude quantitative validation; a controlled study using atomic-force or optical-trap reference measurements on 30–50 cells per condition would establish accuracy and precision. Scaling to patient-derived organoids or primary cells would test translational utility for prognostic stratification in breast cancer.

Future integration with high-throughput microfluidic delivery could enable parallel testing of mechanosensitizing compounds, directly linking subcellular mechanical phenotypes to therapeutic response.