Date of Award

Fall 2023

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Electrical & Computer Engineering

Program/Concentration

Biomedical Engineering

Committee Director

Shu Xiao

Committee Member

Stephen J. Beebe

Committee Member

P. Thomas Vernier

Committee Member

Chunqi Jiang

Committee Member

Siqi Guo

Abstract

The use of nanosecond pulsed electric fields (nsPEF) has emerged as a promising area of research with vast implications across various scientific disciplines. The ability to generate ultra-short, high-voltage electric pulses has paved the way for numerous applications, ranging from fundamental investigations of biological phenomena to the development of innovative medical therapies. The aim of this thesis is to highlight the importance of nsPEF in two critical areas: 1) Understanding the impact of subtle postpulse waveforms through a comprehensive analysis of two common pulse generators and 2) using this knowledge to advance melanoma treatment by enhancing the therapeutic effect of nsPEF with the addition of carbon nanotubes (CNTs). The first part of our study concentrates on comprehending the nuances and differences between two widely utilized pulser generators: the Blumlein line (BL) and the Pulse Forming Line (PFL). Through the investigation of the pulse waveform via the adjustment of the primary pulses in these pulse generators, it was revealed that the post-pulse waveforms possess the capacity to modify cellular reactions and, in some cases, induce distinct cellular responses due to variations in post-pulse characteristics between the two designs. The post-pulse of the BL design exhibited a relatively extended duration, approximately 50 μs (for 40 kV/cm, 100 ns), and had an opposite polarity compared to the main pulse. Conversely, the PFL's post-pulse was considerably shorter, around 2 μs, and shared the same polarity as the main pulse. For the PFL, the LD50 and the thresholds for the dissipation of mitochondrial membrane potential, and an increase in plasma membrane PI permeability and a decrease in trans plasma membrane electron transport (tPMET) were observed at lower pulse numbers compared to the BL design. Furthermore, only the PFL induced an increase in tPMET, thus producing a biphasic effect. However, both pulser designs exhibited similar pulse numbers for generating of mitochondrial reactive oxygen species (ROS). Notably, the PFL reduced spare respiratory capacity (SRC) significantly, while the BL increased SRC. These findings represent a pioneering revelation that the conditions resulting from low-intensity post-pulse charging have a substantial impact on cellular responses, with the potential to selectively induce specific cellular responses. It also underscores the importance of considering these post-pulse factors when comparing results obtained from other pulse waveforms.

However, while the PFL exhibits more robust responses than the BL generator, it is important to acknowledge a limitation in applying of the PFL pulse generator for in vivo studies, as it necessitates higher voltage levels when compared to the BL pulse generator. This increased voltage requirement raises clinical concerns that warrant careful clinical consideration. The second part of this thesis is dedicated to take advantage of multi-walled carbon nanotubes (MWCNT) to enhance the tumor ablation in vivo. MWCNT significantly reduced the necessary pulse conditions for in vitro tumor ablation, lowering it from 0.009 Vs/cm to 0.005 Vs/cm. In vivo, the required pulses were reduced from 1000 to 500, marking at least a twofold improvement. The combined impact of MWCNT to nsPEF treatment for melanoma, using the B16f10 melanoma cell line as an in vitro and in vivo model, has the potential to expand the applications of the PFL pulser in future in vivo studies focused on melanoma immune therapy, with the goal of achieving tumor ablation with in-situ vaccination (ISV) against the threated cancer. Ultimately, this study may pave the way for the translation of this combination approach into preclinical and clinical settings, potentially revolutionizing the management of this devastating disease.

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DOI

10.25777/4pkt-x643

ISBN

9798381446616

ORCID

0009-0003-3047-5322

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