Electrochemical impedance spectroscopy (EIS) is a widely proposed technology in biosensors, but its use in cancer cell detection has been limited. BIDEA LLC’s biosensing strip (BBS) is an innovative technology capable of detecting the presence of telomerase activity (TA) using EIS. Telomerase is an epithelial cancer cell biomarker, which can be used in early cancer detection, prognosis and/or subsequent monitoring of residual cancer disease. This enzyme elongates telomeres during cell division, restoring their length and avoiding cell death. Telomerase is also responsible for the immortalization of cancer cells. The BBS was modified by immobilizing a telomere-like DNA single-strand (ssDNA) for TA detection in uterine biopsy samples. This ssDNA sequence is designed to be recognized explicitly by telomerase and reduces the probability of interference. When BBS is exposed to a telomerase-positive extract, telomerase binds and elongates the probe, blocking electronic and capacitive processes on its interdigtal electrode surface. This resistance to charge transfer (Rct) change is detected by measuring the impedance using EIS, and it is correlated to TA, which indicates the presence of cancer cells. Data obtained in this study demonstrate significant changes in Rct after exposure to telomerase-positive extract in contrast to minor changes exhibited in a telomerase-negative extract. A limit of detection of 2.94 x 10<sup>4</sup> cells/mL was reached using a whole-cell telomerase extraction protocol. A preliminary study, with a small set of uterine biopsy samples suggests the feasibility of using the changes in Rct, at BBS, to distinguish positive from negative cancer samples based of TA levels.

Electrochemical biosensing strip for telomerase activity detection

ACS Spring 2022

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