UBC Theses and Dissertations
Microfluidic electrochemical detection of prostate cancer using telomerase activity Yu, Jie
Prostate cancer has become one of the leading causes of death and the most frequently diagnosed cancer in men, worldwide. It is highly treatable if detected early, but the current screening methods suffer from poor clinical specificity for prostate cancer, leading to unavoidable misdiagnosis and overtreatment. Elevated telomerase activity has been discovered as an indicator of a variety of cancers, including over 92 % of prostate cancers. High clinical specificity of telomerase activity for prostate cancer compared to other prostate anomalies is an important concept promoted in this thesis. To overcome the quantification complexity of current telomerase activity detection techniques, we have designed and demonstrated the TAME assay (Telomerase Activity Measured Electrochemically): a microfluidic biosensor to detect and measure telomerase activity using an electrochemical technique known as E-DNA. Telomerase activity has been successfully correlated to a TAME parameter, TRAP (Telomeric Repeat Amplification Protocol) product concentration, using two E-DNA schemes: ‘signal-off’ and ‘signal-on’. In terms of the E-DNA signal change, telomerase activity and TRAP product concentrations we investigated are linearly correlated, which is promising for prostate cancer screening and detection. The signal-off scheme exhibits electrochemical signal suppression if telomerase activity is present with alternating cyclic voltammetry (ACV) at 50 Hz. The signal-on scheme shows the reverse effect with square wave voltammetry (SWV) at 150 Hz. ‘Signal-on’ and ‘signal-off’ are transferable by altering SWV’s frequency. The limit of detection of ‘signal-off’ and ‘signal-on’ on tested E-DNA chips using un-purified TRAP samples, originated from un-purified prostate cell extracts, are 55 nM and 10 nM. The TAME assay well-differentiates prostate cancer cells from healthy prostate epithelial cells based on telomerase activity expressions.Due to the trend in medical devices towards miniaturization, portability, low power, and high integration capability, in addition to a microfluidic E-DNA chip, a polymerase chain reaction (PCR) microfluidic chip is under development. The PCR chamber is 2.5 mm X 2.5 mm with the integration of micro-heaters and temperature sensors. PCR chips are designed to achieve heating uniformity, which has been evaluated by thermal imagining. In future, a fully integrated TAME chip including both E-DNA and PCR is anticipated.
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