Abstract
Cancer is a leading cause of death worldwide. Cancer has resulted in approximately ten million deaths by 2020, and this number is expected to increase to ~30 million by 2040. Thus, new types of cancer monitoring and detection methodologies are urgently needed. Due to their malignant nature, cancer cells exhibit atypical physical, electrical and biological characteristics compared to their healthy counterparts. Researchers have exploited the distinct electrical properties of cancer cells to improve diagnosis performance. Moreover, the application of electrical signals, i.e., the manipulation of transmembrane-voltage potential in cells, is able to detect a small population of cancer cells. Electroporation is a leading candidate for cell monitoring, genetic engineering, gene therapy and molecular medicine. It involves the use of an external applied electric field to increase the transmembrane bias-voltage of a cell beyond a threshold voltage, allowing for pore formation and an increase in membrane permeability. Electroporation is a ubiquitous phenomenon that affects all types of cells and is an elegant method for enhancing the permeability of cell membranes without invoking unintended side effects associated with chemical methods. Moreover, electroporation techniques such as gene transfection, electrofusion and electrochemotherapy harness transient increase in membrane permeability, while irreversible electroporation induces cell death via a loss of homeostasis for nonthermal tumour ablation. The classical theory of electroporation focuses on the mechanism and timescales of membrane disruption. Although the hydrophilic pores, electrically altered lipids and modulated voltage-gate ion channels increase membrane permeability within microseconds on strong electric field application, the mechanism and timescale (minutes to hours) of membrane resealing is not well understood. Utilizing microscale electroporation systems and a weak electric field could be a promising candidate for these works because they can result in excellent membrane permeabilization, at the same time, maintain good iii cell viability for long-term monitoring. In this thesis, we control the membrane permeabilization kinetics by utilizing a combined low-bias-voltage microscale system for electroporation. This thesis focuses on the development of an impedance-based method for characterizing MCF-7 breast cancer cells during electroporation. We demonstrate, for the first time, the understanding of membrane permeabilization using an electroporation system with microscale features using low bias-voltage stimulations. A recovery time of ~120 min was achieved, which is above the baseline of ~30 min for state-of-the-art electroporation systems with medium cell population in adherent cell lines, enabling the use of low bias-voltage pulses for achieving long-term monitoring of cells after electroporation. Moreover, the thesis describes the nanosecond electroporation of cancer cells. The growing importance of applications based on molecular medicine and genetic engineering is driving the need to develop high-performance electroporation technologies. Although there is a multitude of research focused on exploring new electroporation techniques, the engineering of programming schemes suitable for these electroporation methods remain a challenge. Nanosecond stimulations could be promising candidates for these schemes thanks to their ability to generate a wide range of biological responses. We demonstrate that by utilizing an electroporation system with micro-size features under low-bias voltage, nanosecond stimulations, we can achieve cell recovery time of ~360 min. Atomistic simulations reveal that the manipulation of membrane tension through increasing the number of pulses may increase recovery time. These findings highlight the potential of multiple, nanosecond pulse strategies for the development of next-generation lowpower electroporation systems. Furthermore, the thesis outlines the synthesis of a molecular probe that demonstrates a highly sensitive detection of pancreatic cancer cell for recent biosensor applications. By utilizing electrical system with micrometer-size features using low bias-voltage stimulation and with MoS2/PEG/M13 probes, we can achieve a limit of detection (LOD) of ~15 cells/L, below the average of ~45 cells/µL for current sensing methods using iv medium cell population. Moreover, we also demonstrate that the synthesized MoS2/PEG/M13 nanoprobe is able to exhibit excellent biocompatibility due to the pegylation of MoS2 for nanoprobe concentrations of up to 50 vol.%, exceeding the selected concentration used