A Low-Cost Impedance-Based Detection System for Immune-Mediated Cytotoxicity Targeting Tumor Cells

Abstract

This study presents the design and application of a microfabricated, impedance-based biosensor for real-time, label-free assessment of immune cell-mediated cytotoxicity against adherent cancer cells. The sensor features four series of interdigitated electrodes constructed via photolithography and gold sputtering, incorporating a titanium adhesion layer. Polydimethylsiloxane (PDMS) reservoirs were fabricated and bonded to glass substrates through oxygen plasma treatment to facilitate cell culture. Electrical impedance measurements were conducted using the PalmSens4 potentiostat. During assays, the sensor was maintained within the incubator of an inverted microscope to provide optimal environmental conditions. To test this system, we conducted experiments using two types of immune cells (NK and γδT cells) against SKOV3 ovarian cancer cell line at varying ratios (1:1 and 10:1) and A549 lung cancer cell line at 1:1 and 5:1 . Control conditions included immune cells alone and cancer cells alone, ensuring that observed effects were due to immune cell-mediated cytotoxicity. Impedance readings indicated increased resistance correlating with tumor cell proliferation, followed by a decrease upon immune-mediated cytolysis and subsequent cell detachment. These findings validate the sensor's capability to monitor dynamic cytotoxic interactions effectively. The developed biosensor offers a cost-effective, reusable, and less labor-intensive alternative to conventional cytotoxicity assays such as flow cytometry and xCELLigence systems.Its simplicity and affordability make it particularly suitable for resource-limited laboratories and clinical settings engaged in immunotherapeutic research and applications.