Combustion catalysts have been extensively explored to reduce the emission of hydrocarbons that are capable of triggering photochemical smog and greenhouse effect. Palladium as the most active material is widely applied in exhaust catalytic converter and combustion units, but its high capital cost stimulates the tremendous research on non-noble metal candidates. Here we fabricate highly defective cobalt oxide nanocrystals via a controllable oxidation of carbon-encapsulated cobalt nanoparticles. Strain gradients induced in the nanoconfined carbon shell result in the formation of a large number of active sites featuring a considerable catalytic activity for the combustion of a variety of hydrocarbons (methane, propane and substituted benzenes). For methane combustion, the catalyst displays a unique activity being comparable or even superior to the palladium ones.

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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.

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