Magnetic micellar nanocarrier based on pH-sensitive PEG-PCL-PEG triblock copolymer: a potential carrier for hydrophobic anticancer drugs

In this research, we report a magnetic pH-sensitive polymeric micelle designed for hydrophobic drug carrier in cancer treatment. This carrier was prepared by self-assembly of biodegradable triblock copolymer PEG-PCL-PEG coated on oleate-modified magnetic nanoparticles. The amphiphilic triblock copolymer was synthesized via reaction between the aldehyde group from the hydrophilic component with the amine group of the hydrophobic component. The resulting Schiff base linkage was sensitive to pH. The structure of nanocarrier was characterized by Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (1H-NMR). Morphology and size of the magnetic micellar nanoparticles were characterized by high-resolution transmission microscope (HR-TEM), field emission scanning electron microscope (FE-SEM), atomic force microscopy (AFM), and dynamic light scattering (DLS). The size of magnetic micellar vehicle was observed to be about 90 nm. Nano-sized vehicles have made them suitable for prolonged circulation and accumulation in tumor tissue. Also, the drug release profile was studied at pH = 5.5 (tumor tissue) and pH = 7.4 (healthy tissue) at 37 °C during 80 h, showing a higher rate for drug release at acidic media. In addition, the comparison between the release profile of MNP@PEG-PCL-PEG and MNP@PEG-PCL revealed the superior performance of MNP@PEG-PCL-PEG in terms of its slow release feature. The cytotoxicity of the magnetic nanocarrier was evaluated using MTT assay on MCF-7 cells in vitro conditions, revealing the killing of cancer cells. Therefore, the carrier may have considerable potential as a hydrophobic drug carrier for cancer treatment.