〔Abstract〕 By using purification efficiency and micelle purity as indicators, the effect of ultrafiltration and dextran gel method for purifying transferrin/polycaprolactone (Tfn/PCL) micelles was compared. Methods Coumarin-6 (C6) was used as a fluorescent probe and was loaded into HOOC-PEG-PCL to form PCL micelles by the film-dispersion method. Tfn was then conjugated to the surface of PCL micelles via an amidation reaction, resulting in two types of micelles: Tfn/PCLH and Tfn/PCLL. The pharmaceutical properties of the two types of micelles were characterized. The micelles were then purified through ultrafiltration method and dextran gel method respectively, and the efficiency of the two methods, along with the purity of the final micelles, was compared. The density of Tfn on the surface of PCL micelles was also calculated. Results The hydrated diameter of PCL micelles was approximately 73 nm, and the C6 loading efficiency was around 0.046%. The size increased to 134 nm and 158 nm for Tfn/PCLL and Tfn/PCLH, respectively. The micelle population was monodisperse. The purification results showed that, for the ultrafiltration method, after two and one rounds of purification, the Tfn/C6 ratio stabilized at 23.6 and 3.4 for Tfn/PCLH and Tfn/PCLL, respectively. For the dextran gel filtration method, the Tfn/C6 ratio reached 23.7 for the Tfn/PCLH group after two rounds of purification. However, for the Tfn/PCLL group, the Tfn/C6 ratio increased during four rounds of dextran gel purification, and a significant difference (P = 0.0424) was observed between the first and last filtrations. The density ofTfn in the final micelles were calculated. For the ultrafiltration method, the Tfn density of Tfn/PCLH and Tfn/PCLL were 94.9% and 13.8%, respectively. For the dextran gel filtration method, the density of the two micelles were 95.6% and 14.4%, respectively. For Tfn/PCLL group, the density results revealing a statistically significant difference (P=0.0002). Conclusion The purification efficiency of the two methods is comparable. However, the purity of the final micelles shows a significant difference, with the dextran gel filtration method resulting in higher purity, particularly for the Tfn/PCLL micelles.