Abstract

Targeted tumor therapy relies on drugs that can distinguish tumor cells from normal cells, especially those that can recognize specific receptors or proteins expressed on the surface of tumor cells. However, the heterogeneity of cells in tumors and the protective effects of cell membranes and lysosomes hinder the effectiveness of targeted tumor therapy. Based on the acidic microenvironment of a solid tumor, we constructed an acid-targeting peptide that can firmly bind to the tumor cell membrane in an acidic condition; thereby, it can be employed as a targeting domain to guide antitumor drugs. After coupling the peptide (P12) to the phototherapeutic agent protoporphyrin IX (PPIX) to build a new compound PPIX-P12, in in vitro studies, we found that PPIX-P12 had a high tendency to bind to cancerous cells and showed strong phototoxicity in an acidic medium. This indicated that the acid-targeting peptide might be a promising delivery system for targeting solid tumor cells.