Targeted molecular imaging agents (TMIA) are emerging as useful tools for early diagnosis of cancer and other diseases. These agents couple imaging agents such as near infrared fluorescence (NIRF) dyes or metallic contrast agents such as gadolinium (Gd) used in magnetic resonance imaging (MRI) to targeting agents that bind to biomarker receptors in cancer cells. Our group has developed a modular synthesis of peptide-based TMIAs containing these two agents starting from “puzzle pieces”. Puzzle pieces, or modules, are amino acids with imaging groups bonded to their side chains. These are assembled together to form imaging peptides which are then conjugated to targeting groups. The research goal was to synthesize targeting peptides using solid phase peptide synthesis (SPPS), and then add the imaging puzzle pieces to these in the same SPPS method. SPPS is widely used and has many advantages in the synthesis of TMIAs. The first goal, to learn how to synthesize simple peptides by SPPS, was accomplished. The second goal of making Met-enkephalin, a bioactive penta-peptide, and conjugating the imaging puzzle pieces containing a NIRF dye or gadolinium chelate for MRI by SPPS was also successful. The final goal, to synthesize a deca-peptide, 18-4a, useful for targeting breast cancer and then to couple these same imaging puzzle pieces, to the peptide 18-4 in the last step, was also accomplished.
Department, Program, or Center
School of Chemistry and Materials Science (COS)
Xu, Xinyu, "Solid Phase Synthesis of Modular Peptide-based Targeted Molecular Imaging Agents" (2019). Thesis. Rochester Institute of Technology. Accessed from
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