Preparation of a fluorescent peptide substrate to target tumor-associated macrophages

Abstract

One of the significant challenges in targeting M2 macrophages is the need for specific and high-affinity targeting ligands that can distinguish them from phenotype M1 macrophages. In order to investigate the selectivity of the polypeptide M2pep (YEQDPWGVKWWY) towards M2 macrophages using fluorescence-based techniques, we report here the synthesis and characteriza-tion of the M2pep substrate labeled with a fluorophore. This peptide comprising a 12-amino acid sequence with a spacer consisting of three additional glycines (GGG) was synthesized and cou-pled to Rhodamine B at its N-terminal via microwave-assisted solid-phase synthesis. The structure of the labeled peptide was confirmed by NMR, UV-Vis, fluorescence spectroscopy and mass spec-trometry.