The overall objective of this research project is to develop a high-yield site-specific bioconjugation method for use in developing new cancer therapy agents using the reaction of benzaldehydes with oxyamines. Bioconjugation is the term to describe the development of new pharmaceuticals. It often involves coupling one biomolecule (e.g. monoclonal antibody) with another chemical species (e.g. drug, toxin, radionuclide-binding molecule). The first aim of the project is to synthesize four water-soluble discrete-sized polyethylene glycol (dPEG)-benzaldehyde derivatives, and then determine their relative reaction rates with a water-soluble oxyamine compound. The fastest reacting compound is determined by high performance liquid chromatography (HPLC) analyses and studied further. The second aim in the research project is to conjugate the two most reactive dPEG-benzaldehydes to a monoclonal antibody. The final aim is to assess the bioconjugation reaction of a biotin-oxyamine derivative with the two benzaldehyde-modified antibodies. The biotin-oxyamine conjugation yields will be determined using an avidin-binding (HABA) assay that uses UV quantification.

Photoactivation of compounds such as chlorophyll derivatives results in the excitation of oxygen into a highly reactive singlet state which causes cellular damage and death. This property is used as a cancer therapy, specifically in photodynamic therapy (PDT.) Although PDT has been proven to be effective at eradicating cancer, it has not been widely adopted due to poor penetration of light into body tissues. To avoid this limitation, photosensitizing molecules that absorb light at longer wavelengths are being synthesized to allow deeper tissue penetration. It is possible that the modification of a chlorophyll derivative called chlorin e6 (Ce6) via cycloaddition reactions, such as the Diels-Alder reaction, will lead to a molecule with a wavelength absorption long enough (750-800 nm) to obtain good tissue penetration. Such a molecule will eventually be attached to a cancer-targeting antibody to increase its tumor concentration, which will boost treatment effectiveness and minimize healthy tissue damage. Among the methods employed in the organic syntheses being studied are high-performance liquid chromatography (HPLC), ultraviolet-visible spectroscopy (UV/Vis), nuclear magnetic resonance (NMR), and mass spectroscopy (MS.) The cycloaddition reactions of a Ce6 derivative with a synthesized molecule are currently under investigation. If successful, PDT with this compound can be applied to treat a wider variety of cancers in a targeted and systematic way, while avoiding the nasty side effects of chemotherapy.