Selection and identification of transferrin receptor-specific peptides as recognition probes for cancer cells

Since the transferrin receptor (CD71 or TFRC) is known to be highly expressed in numerous cancers, CD71 has become an attractive target in cancer research. Acquiring specific molecular probes for CD71, such as small molecular ligands, aptamers, peptides, or antibodies, is of great importance for cancer cell recognition and capture. In this work, we chose CD71 as the target for phage display, and after four rounds of positive selection and one round of negative selection, the specific phage library was enriched. After verification and sequence analysis, six peptides were identified to be able to bind to CD71 with high specificity. The specific recognition of the CD71-positive cells was confirmed by flow cytometry and confocal microscopy. Competition experiments demonstrated that peptide Y1 and transferrin (TF) were bound to distinct sites on CD71, indicating that peptide Y1 could replace TF as a potential probe for cell imaging and drug delivery, thus avoiding competition by endogenous TF and side effects. Graphical abstract Six peptides were successfully isolated using in vitro biopanning against CD71 with high specificity and affinity. Peptides Y1 and Y2 would be powerful tools in biosensors and biomedicine due to their unique properties.