There are an increasing number of studies showing the order of drug presentation plays a critical role in achieving optimal combination therapy. Here, a nanoparticle design is presented using ion pairing and drug-polymer conjugate for the sequential delivery of gefitinib (Gi) and doxorubicin (Dox) targeting epidermal growth factor receptor (EGFR) signaling applicable for the treatment of triple negative breast cancers. To realize this nanoparticle design, Gi complexed with dioleoyl phosphatidic acid (DOPA) via ion paring was loaded onto the nanoparticle made of Dox-conjugated poly(L-lactide)-block-polyethylene glycol (PLA-b-PEG) and with an encapsulation efficiency of ~90%. The nanoparticle system exhibited a desired sequential release of Gi followed by Dox, as verified through release and cellular uptake studies. The nanoparticle system demonstrated approximate fourfold and threefold increases in anti-cancer efficacy compared to a control group of Dox-PLA-PEG conjugate against MDA-MB-468 and A549 cell lines in terms of half maximal inhibitory concentration (IC50), respectively. High tumor accumulation of the nanoparticle system was also substantiated for potential in vivo applicability by non-invasive fluorescent imaging.

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The catalytic oxidation of elemental mercury (Hg(0)) vapor is an effective way to enhance mercury removal from coal-fired power plants. RuO 2 catalyst was found to be an excellent Hg(0) oxidation catalyst. When rutile TiO 2 was used as the catalyst support, RuO 2 formed well dispersed nano-layers due to the very similar crystal structures of RuO 2 and rutile TiO 2 , giving higher Hg(0) oxidation activity over anatase TiO 2 support. The RuO 2 /rutile TiO 2 catalyst can be used at the tail end section of the selective catalytic reduction (SCR) unit for Hg(0) oxidation. It showed good Hg(0) oxidation performance under sub-bituminous and lignite coal simulated flue gas conditions with low concentration of HCl or HBr gas. The RuO 2 /rutile TiO 2 catalyst also showed excellent resistance to SO 2 under bituminous coal simulated flue gas, maintaining higher than 90% Hg(0) oxidation with up to 2,000 ppmv SO 2 present. The oxidized mercury in a form of HgCl 2 has a high solubility in water and can be easily captured by other air pollution control systems such as wet scrubbers in coal-fired power plants.

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A mechanistic study using in situ DRIFTS and a kinetic study were conducted on a ruthenium oxide based mercury oxidation catalyst.

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Linear combination fitting of the X-ray Absorption Near Edge Spectroscopy (XANES) was used to quantify oxidized mercury species over RuO 2 /TiO 2 and Selective Catalytic Reduction (SCR) catalysts under different simulated flue gas conditions. Halogen gases play a major role in mercury oxidation. In the absence of halogen gas, elemental mercury can react with sulfur that is contained in both the RuO 2 /TiO 2 and SCR catalysts to form HgS and HgSO 4. 16 In the presence of HCl or HBr gas, HgCl 2 or HgBr 2 is the main oxidized mercury species. When both HCl and HBr gases are present, HgBr 2 is the preferred oxidation product and no HgCl 2 can be found. The formation of HgO and HgS cannot be neglected with or without halogen gas. Other simulated flue gas components such as NO, NH 3 , SO 2 and CO 2 do not have significant 20 effect on oxidized mercury speciation when halogen gas is present.