Label-free optical microrheology with three-dimensional localization and manipulation for intracellular fluids during pyroptosis
Phys. Rev. Applied 26, 014059 – Published 22 July, 2026
DOI: https://doi.org/10.1103/f6hf-92wz
Abstract
Microrheology involves the study of matter’s rheological properties at the microscale and has a wide application in biology, chemistry, and other fields. Exploring the microrheology of intracellular fluids is critical for understanding cell dynamics and related biological processes, and providing insights into cell physiology. Here, we present a label-free, noninvasive microrheology platform that simultaneously integrates holographic optical tweezers for 3D manipulation with double-helix point spread function microscopy for 3D localization. Without using externally labeled particles, an arbitrary endogenous particle within pyroptotic cell can be captured by holographic optical tweezer and moved to desired area in 3D space. Double-helix point spread function microscopy can enhance the imaging contrast of trapped particle and precisely determine its 3D position without prior knowledge of particle size or repeated calibration. The relative viscosity of intracellular fluid is then derived from the trajectory of probe. The label-free microrheology technology was applied to pyroptosis cells for the first time, revealing a relative viscosity gradient from the cell membrane to the nucleus region. This noninvasive approach can avoid external influences on the normal dynamics of cells and provide an in situ platform for the study of intracellular fluid heterogeneity, which will help elucidate the mechanisms of cell death and inflammation.
