For successful HIV therapy, a nanoparticle system must be biodegradable, have reasonable drug loading, must protect the bioactive agent from enzymatic and other degradative mechanisms, must avoid the cells of the reticulo-endothelial system (RES), must interact with cells at the target site and be internalized, must escape from the endosome once internalized and finally, must release its drug payload into the cytoplasm or other target organelle. Our long-term goal is to design a nanoplatform for the co-delivery of anti-HIV drugs and siRNA and to target the siRNA- and drug-loaded nanoparticles to viral anatomical and cellular reservoirs.
The goal of this project is to design and fabricate stealth, antiretroviral drug- and anti-HIV siRNA- loaded nanoparticles using a novel amphiphilic co-polymer to facilitate improved siRNA encapsulation and also its protection from degradation. The use of a nanoparticle system for the co-delivery of drug and siRNA in dual agent therapeutics prevents resistance to drugs or to the RNAi mechanism. The stealth capability is provided by functionalized polyethylene glycol in the copolymer which forms a hydrophilic corona around nanoparticles providing steric stabilization to the system. The functionalized hydrophilic corona will also permit the covalent conjugation of targeting moieties to the surface of the nanoparticle. Thus, this proposal is a first and logical step to achieve our long-term goal to target viral reservoirs.
The following specific aims will be carried out in this project: (a) Synthesis and characterization of a novel stimuli-responsive biodegradable polymer capable of acting as an endosomal “proton sponge”. This polymer with cleavable chemical moieties will facilitate intracellular drug and siRNA release. (b) Fabrication and characterization of corona-core siRNA- and drug-loaded nanoparticles from the synthesized co-polymer. (3) Characterization of the nanoparticles will be done to determine drug and siRNA loading, in vitro release, surface morphology, particle size and zeta potential. Biocompatibility and the anti-HIV efficacy of the blank, drug- and drug and siRNA-loaded nanoparticles will be assessed in vitro against HIV-infected macrophage cells.