Modified ISFET for Real-Time Calcium Ion Sensing in MDA-MB-231 Breast Cancer Cells

Abstract

Transfer of extracellular and intracellular calcium ions (Ca2⁺) plays a crucial role in programmed cell death, with varied Ca2⁺ concentrations associated with cell growth, proliferation, apoptosis, and so on. Real-time monitoring of extracellular Ca2⁺ concentrations ([Ca2+]e) can provide valuable quantitative insights into programmed cell death, which may greatly benefit cancer therapy and other biological applications. This study used a modified ion-sensitive field-effect transistor (ISFET) as a platform for Ca2⁺ sensing. The ISFET device was functionalized with a Ca2⁺-selective membrane containing polyurethane (PU) and calcium ionophore II. The Ca2⁺-FET device exhibited a sensitivity of 35 ± 3 mV/pCa (pCa 0–5) toward Ca2⁺ with insignificant cross-sensitivity to other ions, such as sodium (Na⁺) and potassium (K⁺). The device was applied to monitor [Ca2+]e concentrations in the MDA-MB-231 breast cancer cell culture, showing sufficient reliance in detecting Ca2⁺ concentrations (0.1 mM to 1 M (pCa 0–5)) correlated with cellular activities. This technique offers a noninvasive and label-free approach for real-time Ca2⁺ monitoring in cell culture, with potential applications in cancer research and therapeutic development.