(635f) Rational Design of Polypeptides for the Functionalization of Novel Nanoparticles

Bioconjugate chemistry has long been used to combine biomolecules to alter functions and to add properties, especially to larger biomolecular assemblies such as virus-like particles (VLPs). However, there exist several limitations to effectively conjugating two molecules if the available surfaces are sterically hindered or electrostatically repulsive. Furthermore, the reactive moieties must be properly oriented and activated to achieve effective conjugation. Previous strategies to overcome these issues have involved modifying the composition of the surfaces to reduce electrostatic repulsion or adding soluble enhancers to the reaction. However, these strategies often disrupt the structure and functions of the molecule. Alternatively, we can take advantage of the chemical environment by selecting a protein tag that recognizes its target by ion pairing. Using this strategy of “facilitated conjugation”, we have designed a series of polypeptides to improve the efficiency of Huisgen Copper (I)-Catalyzed Azide-Alkyne cycloaddition of a variety of ligands including a scFv and a luciferase to the negatively charged surface of the Hepatitis B core VLP. We introduce the concept of facilitated conjugation and evaluate the design rules to further improve conjugation efficiency. We are currently utilizing this strategy to generate functionalized VLPs as vaccines and cancer cell detection.