The aptamer-functionalized nanoparticles also demonstrated improved anti-tumor efficacy in MCF7 cells compared to doxorubicin-encapsulated non-targeted nanoparticles and free doxorubicin.228 Similarly, tryptophan–phenylalanine dipeptide nanoparticles (DNPs) functionalized with the MUC1 aptamer and doxorubicin can specifically target MUC1-positive human lung cancer A549 cells instead of MUC1-negative L929 cells, and can be utilized for MUC1-positive cancer cell imaging and real-time drug release monitoring.229. Here, MUC1 is linked to lung cancer.