Doxorubicin-loaded Fmoc-phenylalanine Protocol

Standard 9-fluorenylmethoxycarbonyl (Fmoc)-protected amino acid, Ac-phenylalanine, N-hydroxy-benzotriazole (HOBt), Wang resin, and 4-dimethyl-aminopyridine (DMAP) were purchased from GL Biochem (Shanghai, China). Doxorubicin hydrochloride (DOX) was obtained from Aladdin (Shanghai, China). All other unspecified reagents were purchased from Sigma-Aldrich (St. Louis, MO, USA). Murine K12 osteosarcoma cells and normal NIH3T3 fibroblast cells were obtained from Keygen Biotech (Jiangsu, China) and cultured in a humidified incubator (37 °C, 5% CO₂). Female BALB/c mice with K12 cells were supplied by the Qinglong Mountain Center (Jiangsu, China). All animal procedures were approved and supervised by the Animal Experiment Ethics Committee of the Army Medical University (Chongqing, China).