Date of Award

Summer 8-31-2025

Document Type

Open Access Thesis

Degree Name

Master of Science (MS)

Department

Physics, Applied

First Advisor

Jonathan Celli

Second Advisor

Chandra Yelleswarapu

Third Advisor

Akira Sone

Abstract

Background: Photodynamic Therapy (PDT) utilizes specific wavelengths of light to activate photosensitizing chemical compounds, known as photosensitizers, which induce the generation of cytotoxic reactive oxygen species (ROS) for the targeted destruction of cancer cells. Among various photosensitizers for PDT, Protoporphyrin IX (PpIX) is widely employed in oncology and dermatology due to its natural in situ generation via the metabolic conversion of 5- aminolevulinic acid (ALA), a non-phototoxic prodrug. Systemic administration of ALA after 3-6 hr drug delay leads to peak PpIX accumulation in tissues, facilitating therapeutic and diagnostic applications. However, PpIX can persist in the skin for 24–48 hours post-treatment, posing a risk of phototoxicity, especially in patients with sensitive skin. Monitoring residual PpIX is therefore essential for evaluating treatment efficacy and determining safe discharge timing. By integrating frugal engineering with clinically validated fluorescence detection principles, this study addresses an unmet need in PDT patient management. It aims to develop an affordable, portable Cutaneous PpIX Detection (CPD) device for real-time fluorescence (FL) monitoring, leveraging the distinct optical properties of PpIX. v Methods: A point-of-care portable Cutaneous PpIX Detection (CPD) device was designed, integrating a 405 nm LED excitation source, a 600 nm long-pass optical filter, and a photodiode sensor. The system was calibrated using standardized PpIX solutions and validated with hydrogel phantom models, 3D cancer cell cultures, and murine models. Results: The CPD device demonstrated high sensitivity in detecting low PpIX concentrations, correlating well with commercial fluorescence detection systems. The cost-effective design enhances clinical feasibility in resource-limited settings. Conclusions: This study presents a viable solution for post-PDT PpIX monitoring, thereby improving patient management and enhancing PDT accessibility. Future advancements will explore automated signal interpretation and sustainable power sources for broader biomedical applications.

Comments

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