An afatinib-based theranostic fluorescent probe for cancer cells and its applications in monitoring pH changes during treatment

Among the serious diseases threatening human health, cancer is bound to bear the brunt. People have been committed to accurate diagnosis and treatment of cancer. The emergence of integrated diagnostic and therapeutic reagents has given people a new weapon against cancer. The development of novel theranostic reagents is of great significance for overcoming cancer. Therefore, in this paper, afatinib with the ability of targeting epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor-2 (HER2) and methylpiperazine functionalized naphthalimide were connected by a flexible long chain, after that a theranostic probe AFNI-pH was successfully developed. The probe not only distinguished cancer cells because of the abnormal high expression of these two receptors and the acidic microenvironment in cancer cells, but also exhibited significant toxicity to A549 cells with high expression of EGFR resulting from the inhibitory effect of afatinib. In addition, probe AFNI-pH could visualize the pH changes in A549 cells during treatment, providing a visual tool for studying afatinib resistance related to tumor environment, and helping to consider strategy of combined medication in the future cancer treatment.