Bioelectric Spectra Characterization of Individual Cancer Cells with Electrical Impedance Spectroscopy
Based on the literature, most cancer associated deaths are attributed to metastasis. Yet, the process of metastasis is one of the least understood aspects of the disease. It is now believed that the metastatic process starts in the early stages of cancer progression. However, very few cells are able to colonize in a distal site, making the process highly inefficient. This inefficiency gives us a window of opportunity to detect cancer at the early stages by hunting down cancer cells in the bloodstream. Many groups are attempting to develop a system to quantify and classify circulating tumor cells (CTCs) and cancer stem cells (CSCs) in blood biopsies. This task has proven difficult mainly due to the low number of tumor cells found in blood and the lack of inclusive surface markers for target cell detection. We propose a different approach to identify single CTCs and CSCs, which integrates microfluidics with electrical probing at the single cell level with the use of Electrochemical Impedance Spectroscopy (EIS). EIS was employed to measure the impedance of the cell and the device by the application of a low voltage AC waveform at frequencies ranging from 1Hz to 300kHz. Based on the electrical recordings of each cell, we expect to find a characteristic bioelectric fingerprint for each cell line. A biosensing platform was developed through which EIS and single cell microfluidics were used to assess the electrical response of Hela and MDA MB 231 cancer cell lines. The electrical recordings were analyzed based on the total impedance and phase angle as a function of frequency. Initial observation shows a high level of differentiation between the EIS data of the tested cell lines in the frequency ranges of 10Hz - 100Hz and 100kHz - 300kHz. These preliminary findings show that we can in fact use EIS to quantify and classify cells of interest in a population if the bioelectric fingerprint has been previously recorded. However, in a clinical setting it would be more useful to detect and possibly enrich unknown cells found in blood biopsies to study them based on molecular profiling assays.