Application of multivalent interactions for recognition imaging and delivery of therapeutics

Multivalency is an important phenomenon that guides numerous biological interactions. It has been utilized in design of therapeutics and drug candidates. Hence, this study attempts to develop analytical tools to study multivalent interactions and design multivalent ligands for drug delivery and therapeutic applications.

Atomic Force Microscopy (AFM) has been envisioned as a means of nanodiagnostics due to its single molecule sensitivity. However, the AFM based recognition imaging lacks a multiplex capacity to detect multiple analytes in a single test. Also there is no user friendly wet chemistry to functionalize AFM tips. Hence, an uncatalyzed Click Chemistry protocol was developed to functionalize AFM tips. For multiplexed recognition imaging, recognition heads based on a C3 symmetrical three arm linker with azide functionalities at its ends were synthesized and the chemistry to attach them to AFM tips was developed, and these recognition heads were used in detecting multiple proteins simultaneously using AFM.

A bis-Angiopeptide-2 conjugate with this three-arm linker was synthesized and this was conjugated with anti-West Nile virus antibody E16 site specifically to target advanced West Nile virus infection in the Central Nervous System. The bis-Angiopeptide-2 conjugate of the antibody shows higher efficacy compared to a linear linker-Angiopeptide-2 conjugate of the antibody in in vitro studies and currently the efficacy of this antibody conjugate in studied in mice. Surface Plasmon Resonance imaging (SPRi) results indicate that the conjugation does not affect the antigen binding activity of the antibody very significantly.

A Y-shaped bisbiotin ligand was also prepared as a small sized antibody mimic. Compared to a monovalent biotin ligand, the y-Bisbiotin can cooperatively form a significantly more stable complex with streptavidin through intramolecular bivalent interactions, which were demonstrated by gel electrophoresis, SPR and AFM. Continuing on these lines, a four-arm linker was synthesized containing three single chain variable fragments (scFv) linked to the scaffold to form a tripod base, which would allow them to concomitantly interact with a trimeric Glycoprotein (GP) spike that has a “chalice” configuration. Meanwhile, a human IgG1 Fc is to be installed on the top of the tetrahedron, exerting effector functions of a monoclonal antibody.