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Muhammad Ajaz Hussain,Khawar Abbas,Muhammad Sher,Muhammad Nawaz Tahir,Wolfgang Tremel,Mohammad Saeed Iqbal,Muhammad Amin,Munair Badshah 한국고분자학회 2011 Macromolecular Research Vol.19 No.12
This article presents the synthesis of novel hydroxypropylmethylcellulose (HPMC)-aspirin (ASP) conjugates,i.e. macromolecular prodrugs, through the reaction of HPMC with ASP after its in situ activation by 4-methylbenzenesulfonyl chloride. The highly pure ASP prodrugs obtained by this homogeneous and elegant esterification method were characterized using different spectroscopic and chromatographic techniques. Nanoparticulate drug design was successfully achieved by the conversion of free hydroxyls of the polymer into acetates. Transmission electron microscopy and scanning electron microscopy showed nanoparticle formation with the major population size distribution of around 450 nm. Nevertheless, the pharmacokinetics of the HPMC conjugates were studied using high performance liquid chromatography. The pharmacokinetic data indicated that a single dose of 132.6 mg of HPMC-ASP was well tolerated in animal studies without any adverse effects. The maximum plasma concentration (C_max) of HPMC-ASP was found to be 14.6 μg·L^-1 with a t_max of 1 h. The plasma half-life and clearance and the volume of HPMC-ASP distribution were 4.6 h, 3.23 L·h^-1, and 21.8 L·kg^-1, respectively. The elimination of HPMC-ASP followed first-order kinetics with r^2 of 0.9643. The results presented in this paper show the great potential of HPMCASP as a more effective, safe, and stable prodrug.
Birkel, Alexander,Lee, Yong-Gun,Koll, Dominik,Meerbeek, Xavier Van,Frank, Stefan,Choi, Mi Jin,Kang, Yong Soo,Char, Kookheon,Tremel, Wolfgang The Royal Society of Chemistry 2012 Energy & environmental science Vol.5 No.1
<p>Highly efficient dye-sensitized solar cells (DSSCs) with excellent long-term stability were fabricated based on tin(<SMALL>IV</SMALL>) oxide (SnO<SUB>2</SUB>) nanocrystals with tunable morphologies and band energy levels. The nanocrystals were prepared by a facile, fast, and energy-saving microwave-assisted solvothermal reaction. Through variation of the precursor base used during nanocrystal synthesis control over morphology was achieved—precursor metal cations are known to have a strong influence on the growth process of SnO<SUB>2</SUB> nanostructures. A simple and economic way to prepare semiconducting pastes for photoanodes was devised. The photovoltaic performance of dye-sensitized solar cells based on SnO<SUB>2</SUB> photoanodes was investigated. A very high power conversion efficiency of up to 3.2%, based on very high <I>V</I><SUB>oc</SUB> and comparable <I>J</I><SUB>sc</SUB> and FF [under 1 Sun condition (AM 1.5, 100 mW cm<SUP>−2</SUP>, with shading masks)] was achieved, reporting the highest efficiency value for the cells based on unmodified SnO<SUB>2</SUB> nanocrystals so far. In order to elucidate the efficient cell behavior, electrochemical properties such as the charge transport in the photoanodes as well as SnO<SUB>2</SUB>/electrolyte interfacial properties were investigated. Uncharacteristically for DSSCs, all devices tested in the present study show an unusual long-term stability under ambient conditions over several weeks.</p> <P>Graphic Abstract</P><P>Dye-sensitized solar cells (DSSCs) with efficiencies reaching up to 3.2% have been fabricated employing SnO<SUB>2</SUB> nanoparticles with different morphologies, prepared by a fast, facile and energy-efficient microwave-assisted solvothermal synthesis. <img src='http://pubs.rsc.org/ej/EE/2012/c1ee02115j/c1ee02115j-ga.gif'> </P>