UC San Diego

The persistent threats of chemical warfare agents (CWAs) across diverse settings, spanning military and civilian domains, necessitate the development of innovative defense technologies to counteract their devastating effects. This thesis focuses on two pivotal research paradigms in CWA defense: the development of rapid-response sensors for field-deployable detection and the creation of fast-acting detoxifying materials. Existing systems often fall short in terms of efficacy and applicability. Porous silicon (pSi), distinguished by its versatile physicochemical properties and biocompatibility, emerges as a promising platform to drive advancements in the technologies imperative for CWA sensing and detoxification. The thesis is structured into three interconnected phases: First, it delves into sensor development. A ratiometric CWA sensor is designed using pSi photonic crystals incorporating analyte-specific indicator dyes. These sensors are capable of detecting HF and HCN vapors below their Immediately Dangerous to Life or Health (IDLH) levels, with minimal sensor drift amidst common environmental interferences. They effectively discern the target analyte from complex background matrices, emphasizing their practical utility. Second, the thesis focuses on the development of catalytic materials for detoxifying CWAs. Using a model enzyme nanoluciferase, a systematic study investigates the impact of encapsulation chemistry on the enzyme when confined within the porous structure of pSi nanocages. This leads to enhanced enzyme stability for downstream applications. Building upon insights from the model enzyme, pSi nanoparticles were optimized as host materials for immobilizing organophosphate (OP)-detoxifying enzymes. Through systematic refinement of pSi surface chemistry and enzyme loading, the detoxification capabilities of the immobilized enzyme by the pSi nanocage against OPs are significantly enhanced relative to the native enzyme, protecting the essential acetylcholinesterase (AChE) mechanism from nerve agent VX inhibition. In the final phase, the thesis explores the fabrication of a nanocomposite hydrogel for contact lenses, addressing the unmet need for ocular protection against OP poisoning.