Label-free distinguish proliferative and apoptotic responses of glioma cells with terahertz metamaterials

Glioma exhibits various sensitivities to the same treatment due to its high invasiveness and heterogeneity, which are typically assessed by the proliferative and apoptotic cell activities. Currently, classical label methods for cell proliferation and apoptosis detection are destructive and time-consuming, and spectral and electrochemical technologies without label can hardly distinguish the proliferation and apoptosis responses. Here, a label-free approach to simultaneously detect the proliferative and apoptotic features of glioma cells with terahertz metamaterials is reported for the first time. The biosensor comprises periodic metamaterial resonators, whose frequency shifts in ∆f as the cell number and state vary. Three glioma cell lines under the most sophisticated therapies, i.e., chemotherapy and radiotherapy, are investigated. Various frequency-shift responses are observed for the live and apoptotic cells, revealing different refractive indices for them. By using standard biological assays to identify cell numbers and proliferation and apoptosis rates, the relation between ∆f and the numbers of live and apoptotic cells is fitted, which consequently reveals the relation of ∆f with respect to both proliferation and apoptosis rates unprecedentedly. This work paves a new way to study the proliferative and apoptotic responses of tumor cells, showing promising potential to guide individualized tumor treatments fast and label-free.