(191ce) Engineering Hepatitis B Viral-like Particles into Protein Delivery Vehicles

Nanodevices, which can specifically target diseased cells via molecular level signals and deliver high therapeutic payloads, have attracted considerable interest as next generation platforms for advanced disease therapeutics. A significant challenge in engineering these therapeutic nanodevices is incorporating a reliable release mechanism to enable the dispersion of the drug payload within the cellular environment after uptake of the nanodevice. The reducing environment of the cytosol has often been exploited to release molecules tethered through disulfide bonds; however, ability to form these reversible bonds in vitro is hindered by nondiscriminatory free cysteines and the formation of unwanted homodimeric byproducts. In nature, error in disulfide bond formation in proteins is abated by tertiary and quaternary structure, which stabilizes the correct orientation of the cysteine residues. Inspired by this, we have developed a genetically encoded protein module which uses affinity domains to drive the formation of disulfide bonds between the nanodevice and cargo. Furthermore, we have combined this technology with our previously developed Hepatitis B Virus-Like Particle (HBV VLP) nanocarrier platform to create a protein delivery device capable of selectively targeting cancer cells and releasing proteins into the cytosol.