Yumeng Wei,1– 3,* Mingtang Zeng,1– 4,* Chao Pi,1– 3 Hongping Shen,2,5 Jiyuan Yuan,2,5 Ying Zuo,2,6 Jie Wen,1– 3 Pu Guo,7 Wenmei Zhao,1– 3 Ke Li,1– 3 Zhilian Su,1– 3 Xinjie Song,8,9 Shaozhi Fu,10 Robert J Lee,11 Ling Zhao2,3 1Key Laboratory of Medical Electrophysiology, Ministry of Education, School of Pharmacy of Southwest Medical University, Luzhou, 646000, People’s Republic of China; 2Luzhou Key Laboratory of Traditional Chinese Medicine for Chronic Diseases Jointly Built by Sichuan and Chongqing, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, 646000, People’s Republic of China; 3Central Nervous System Drug Key Laboratory of Sichuan Province, Southwest Medical University, Luzhou, 646000, People’s Republic of China; 4Department of Clinical Pharmacy, West China Hospital, Sichuan University, Chengdu, 610041, People’s Republic of China; 5Clinical Trial Center, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, 646000, People’s Republic of China; 6General Department, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, 646000, People’s Republic of China; 7Department of Pharmacy, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, People’s Republic of China; 8School of Biological and Chemical Engineering, Zhejiang University of Science and Technology, Hangzhou, 310023, People’s Republic of China; 9Department of Food Science and Technology, Yeungnam University, Gyeongsan-si, Gyeongsangbuk-do, 38541, Republic of Korea; 10Department of Oncology, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, People’s Republic of China; 11Division of Pharmaceutics and Pharmacology, College of Pharmacy, The Ohio State University, Columbus, OH, 43210, USA*These authors contributed equally to this workCorrespondence: Shaozhi Fu, Department of Oncology, The Affiliated Hospital of Southwest Medical University, Luzhou, 646000, People’s Republic of China, Tel +86 830-3165698, Fax +86 830-3165690, Email shaozhifu513@swmu.edu.cn Ling Zhao, Luzhou Key Laboratory of Traditional Chinese Medicine for Chronic Diseases Jointly Built by Sichuan and Chongqing, The Affiliated Traditional Chinese Medicine Hospital of Southwest Medical University, Luzhou, 646000, People’s Republic of China, Tel/Fax +86 830 3160093, Email zhaoling-998@163.comPurpose: Paclitaxel (PTX) has been widely utilized for the treatment of breast cancer. However, drawbacks, such as poor aqueous solubility, rapid blood clearance and severe toxicity, greatly reduce its efficacy and safety. Herein, a novel self-developed curcumin derivative (CUD) was chosen as the carrier to develop a long-acting PTX nano-delivery system (PTX-Sln@CUD) in order to improve its pharmacokinetic behavior, anti-breast cancer efficacy and safety.Methods: PTX-Sln@CUD was prepared using solid dispersion and ultrasonic technology. Relevant physical and chemical properties, including stability and release behavior, were characterized. The clearance of PTX-Sln@CUD in vivo was studied by pharmacokinetic experiments. The anti-tumor activity of PTX-Sln@CUD was investigated in vitro and in vivo. Hemolysis experiments, acute toxicity and cumulative toxicity studies were performed in mice to determine the safety of PTX-Sln@CUD.Results: The average particle size, PDI, Zeta potential, encapsulation efficiency and loading efficiency of the PTX-Sln@CUD were 238.5 ± 4.79 nm, 0.225 ± 0.011, − 33.8 ± 1.26 mV, 94.20 ± 0.49% and 10.98 ± 0.31%, respectively. PTX-Sln@CUD was found to be stable at room temperature for half a year. The cumulative release rates of PTX-Sln@CUD at 24, 96 and 168 h were 17.98 ± 2.60, 57.09 ± 2.32 and 72.66 ± 4.16%, respectively, which were adherent to zero-order kinetics. T1/2, MRT (0-t) and AUC (0-t) of the PTX-Sln@CUD group were 4.03-fold (44.293 h), 7.78-fold (38.444 h) and 6.18-fold (14.716 mg/L*h) of the PTX group, respectively. PTX-Sln@CUD group demonstrated stronger anti-breast cancer activity than the PTX group. Importantly, the PTX-Sln@CUD group was safer compared to the PTX group both in vitro and in vivo.Conclusion: PTX-Sln@CUD was verified as promising therapeutic nanoparticles for breast cancer and provided a novel strategy to solve the problem of low efficacy and poor safety of clinical chemotherapy drugs.Graphical Abstract: Keywords: breast cancer, long-acting, paclitaxel nanoparticles, curcumin derivative