Detection of Dielectrically Heterogeneous 3D Multicellular Objects with Microwave Dielectric Spectroscopy

Multicellular 3D biological models, also called spheroids or microtissues, are considered very promising for drug screening and cancer studies, as they integrate a structural heterogeneity and therefore exhibit a physiological complexity that closely mimics in vivo tissues. Such a model is usually characterized with optical techniques. These are very efficient but present however the implication of labels and high-cost equipment. To complete such methods, microwave dielectric spectroscopy presents attractive features, as it is non-invasive, label-free and rapid. To demonstrate its ability to evaluate 3D heterogeneous bio-models, a microwave biosensor suitable for the analysis of such bio-objects is evaluated. Three different types of elements with constitutional dielectric heterogeneity are used, spheroids with living HepG2 cells, polystyrene beads and the combination of these two models considered as hybrid spheroids. A clear discrimination of the different model categories is obtained, demonstrating the ability of the microwave sensing technique to detect a 3D bio-object with heterogeneous dielectric structuration.