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

Area of Science:

• Biomedical Engineering
• Cell Biology
• Biosensing Technology

Background:

• Extracellular and intracellular calcium ion (Ca²⁺) transfer is vital for programmed cell death.
• Monitoring extracellular Ca²⁺ concentrations ([Ca²⁺]_e) offers quantitative insights into cell death processes.
• Such monitoring has potential applications in cancer therapy and biological research.

Purpose of the Study:

• To develop a noninvasive, label-free biosensor for real-time monitoring of extracellular Ca²⁺ concentrations.
• To utilize a modified ion-sensitive field-effect transistor (ISFET) as a Ca²⁺ sensing platform.
• To assess the device's performance in detecting Ca²⁺ levels correlated with cellular activities.

Main Methods:

• A modified ion-sensitive field-effect transistor (ISFET) was functionalized with a Ca²⁺-selective membrane.
• The membrane incorporated polyurethane (PU) and calcium ionophore II for selective Ca²⁺ binding.
• The developed Ca²⁺-FET device was used to monitor [Ca²⁺]_e in MDA-MB-231 breast cancer cell cultures.

Main Results:

• The Ca²⁺-FET device demonstrated high sensitivity (35 ± 3 mV/pCa, pCa 0-5) toward Ca²⁺.
• The sensor exhibited negligible cross-sensitivity to other ions like sodium (Na⁺) and potassium (K⁺).
• The device reliably detected Ca²⁺ concentrations (0.1 mM to 1 M) in cell cultures, correlating with cellular activities.

Conclusions:

• The developed Ca²⁺-FET offers a sensitive and selective platform for real-time extracellular Ca²⁺ monitoring.
• This noninvasive technique provides valuable data for understanding cellular processes, particularly in cancer research.
• The biosensor holds potential for advancing cancer therapy development and other biological applications.