Editorial: Rheology and complex fluids in biomedical applications

Editorial on the Research Topic Rheology and complex fluids in biomedical applicationsComplex fluids are ubiquitous in biomedical applications, and their mechanical properties are relevant for optimizing products used by patients and healthcare professionals, as well as for conducting research on native biological processes and disease progression to facilitate development of treatments or improve medical practices.This Research Topic sits at the intersection of chemistry, biology, and physics, encompassing fundamental insights, biomedical analytical techniques, and the links between mechanical properties of biological materials such as cells, spheroids, bacterial biofilms, cerebrospinal, and follicular fluids, and their potential medical outcomes.The motion of micron-sized organisms in a fluid results from the interplay of shape, mechanical motion of other constituents, and responses to chemical stimuli.Inspiration can be drawn from this natural behavior to create micro-particles and micro-robots, optimizing their size, shape, mechanical properties, and energy sources.This field includes extensive studies on the motion of active particles in fluids triggered by mechanical or chemical stimuli.For example, Raj et al. explore how active bent rods combine mechanical movement with chemical modes such as diffusiophoresis, providing insights into controlling particle trajectories in complex fluids.Moving from artificial constructs to biological entities, cells are the foundation of life, with their morphology and mechanical properties closely linked to medical outcomes.Quantitative phase imaging (QPI) of live cells enables label-free assessment of cell morphology and quantitative estimation of cell thickness and volume.One advanced QPI technique is digital holographic microscopy (DHM), a high-resolution phase imaging method.To analyze a larger number of cells, researchers use holographic flow-cytometry, flowing multiple cells through transparent micron-sized channels.As cells rotate during flow, a three-dimensional refractive index map can be built.However, the motion of 1 cell can influence other nearby cells, potentially altering the imaging.Vitolo et al. use numerical simulations to evaluate the impact of these hydrodynamic interactions on cell imaging through holographic flow-cytometry.Beyond individual cells, cell spheroids offer a model to study cell-cell and cell-matrix interactions in a three-dimensional microenvironment.Cell spheroids are threedimensional cell cultures that form sphere-like structures during cell proliferation.