Surface modification of MPEG-b-PCL-based nanoparticles via oxidative self-polymerization of dopamine for malignant melanoma therapy

To enhance the therapeutic effects of chemotherapy on malignant melanoma, paclitaxel (PTX)-loaded methoxy poly(ethylene glycol)-b-poly(ε-caprolactone) nanoparticles (MPEG-b-PCL NPs) that had their surfaces modified with polydopamine (PTX-loaded MPEG-b-PCL NPs@PDA) were prepared as drug vehicles. The block copolymer MPEG-b-PCL was synthesized by ring-opening polymerization and characterized by proton nuclear magnetic resonance spectroscopy and gel permeation chromatography. The PTX-loaded NPs were prepared by a modified nanoprecipitation technique. The PTX-loaded NPs and PTX-loaded NPs@PDA were characterized in terms of size and size distribution, zeta potential, surface morphology, drug encapsulation efficiency, and drug release. Confocal laser scanning microscopy showed that coumarin-6-loaded NPs@PDA could be internalized by human melanoma cell line A875 cells. The cellular uptake efficiency of NPs was greatly enhanced after PDA modification. The antitumor efficacy of the PTX-loaded NPs@PDA was investigated in vitro by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and in vivo by a xenograft tumor model. The PTX-loaded NPs@PDA could significantly inhibit tumor growth compared to Taxol(®) and precursor PTX-loaded NPs. All the results suggested that the PTX-loaded MPEG-b-PCL NPs that had their surfaces modified with PDA are promising nanocarriers for malignant melanoma therapy.