Diblock copolymers of poly(ethylene glycol) (PEG) and poly(ε-caprolactone) (PCL) bearing a biotin ligand, were self-assembled into micelles. Superparamagnetic iron oxide (SPIO) nanoparticles and an anticancer drug methotrexate (MTX) were coencapsulated within the micelles less than 100 nm in diameters.
The preparation process was optimized by a systematic multi-objective-optimization approach in terms of the encapsulation ratio (ER %, Y1), drug-loading efficiency (DL %, Y2) and the percentage of MTX precipitated from the drug-loaded mixed micelles after 30min and 6h incubation at 37ºC (MTX precipitated %, Y3 and Y4) of the resulting nanocarriers. A combination of the stirring rate, ultrasonic power and drug/polymer ratio, accounted for nearly 79% of the variation in drug-loading efficiency. The final entrapment ratio, loading efficiency and MTX % precipitated corresponding to the optimal conditions were 70.938, 5.665 and 6.885 respectively.
Moreover, in vitro release behavior of MTX was also investigated. The result shows, MTX is physically entrapped inside B-PEG-PCL self-aggregated nanoparticlesis.