UC San Diego

While enzymes of non-human origin are attractive for therapeutic and diagnostic applications like in cancer, viral infection and brain diseases, their clinical use has been limited due to the immune response against foreign proteins. These enzyme can been hidden and incorporated in particles that are capable of harnessing ultrasound energy such that focused ultrasound can expose the enzyme to its substrate. However, the immune evasion and delivery specificity are key challenges needing to be addressed. We propose a silica coated enzyme encapsulated lipid nanoparticle (SiLi) that protects the enzymes encapsulated within its hollow core of the liposome from immune attack whilst allowing access to their substrates through its porous secondary silica layer. The accessibility of the substrate to the enzyme is controlled through ultrasound.

In this dissertation, The unique fabrication process of the liposome is discussed whose intergrity can be exploited by the application of ultrasound. The ability of the secondary coating prevents the proteases to neutralize the enzymes in SiLi particles whist maintaining structural integrity. The residence time of the liposomes and SiLi are also evaluated through intramuscular injections at the hind limbs in vivo. Additionally different methods to fabricate silica on top of the liposomes are also discussed.

Finally the application of SiLi with different enzymes for therapy and diagnosis are also explored. Enzyme based oxidative therapy were investigated to generate ROS at the site of injection. Glucose oxidase was used to test the therapeutic efficacy in cells as well as tumor xenografts. SiLi loaded with cocktail of enzymes are fabricated to optically detect small molecules like ACh. ACh is an important neurotransmitter which play a key role in the manifesting Alzheimer’s and Parkinson’s pathology. Thereby a nanoparticle optical probe to detect ACh plays a pivotal role in brain mapping which could provide insights to disease progression and possible therapeutic

targets.