Near-Infrared-Responsive Peptide that Targets Collagen Fibrils to Induce Cytotoxicity.

A novel conjugate, PHG10 dye, was synthesized using a collagen peptide and a near-infrared (NIR)-responsive dye to achieve targeted cytotoxicity. The collagen peptide motif, -(Pro-Hyp-Gly)10 - (PHG10), was incorporated for targeting collagen fibrils that are excessively produced by activated fibroblasts around tumor cells. PHG10 dye was purified by HPLC and identified by MALDI-MS. The phototoxicity and cytotoxicity of PHG10 dye were examined using human glioma cells (HGCs). Fluorescent images indicated that PHG10 dye preferably assembled to collagen-coated HGCs compared with noncoated HGCs. Under irradiation with NIR light, effective cytotoxicity was observed on collagen-coated HGCs within 20 min. Because phototoxicity and cytotoxicity are dependent on the assembled amount of PHG10 dye, the targeting of collagen fibrils by the collagen peptide motif PHG10 is assured.