Photonic crystals in biology

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Poster Session, Tuesday, June 15 Theme A1 - B702 New stationary phase based on stabilized by o rga nic liga nds gold nanoparticles on silica surface for HPLC Irina Ananieva 1 *, Yana Elfimova 1 , Aleksandr Majouga 1 , Nikolay Zyk 1 and Oleg Shpigun 1 1 Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia Abstract-New nanohybrid materials for HPLC based on gold nanoparticles supported on silica gel and stabilized by L-cystein, pyridine, citrate and ascorbic acid are synthesized. The possibility of separation of different model compounds in normal-phase mode of chromatography is studied. Nowadays gold nanoparticles attract a great deal of attention in a wide variety of scientific fields and technology due to their unique chemical and physical properties, which are directly related to chemical composition, size and surface structural characteristics of nanoparticles [1]. Materials based on gold nanoparticles have already found widespread application in medicine, optoelectronics, catalysis, biochemical sensors development [2]. It seems to be very perspective to use gold nanoparticles supported on oxide surface and stabilized by sulfur-bearing organic ligands for creation of new class of separation materials for liquid chromatography. Due to the specific structures and additional interaction between gold nanoparticles on the stationary phase surface and separating compounds a good resolution of different organic compounds may be achieved. The main advantage of these selectors is covalent attaching of organic ligands on the surface of nanoparticles that allows to synthesize a stable sorbent and obtain reproducible data. Nanohybrid materials have been synthesized by follow method. In the first one gold nanoparticles with the 10 nm size have been prepared by reduction H[AuCl 4 ] in an aqua solution by sodium citrate, and then they have been adsorbed on silica gel. In the last stage citrate-ions have been substituted for such organic ligands as L-cystein (column 1), pyridine, ascorbic acid. The scheme of the synthesized stationary phase with organic ligand is presented on Figure 1. aminopyridines had the greatest capacity coefficients on all stationary phases, and the retention rose with the growth of investigating compounds polarity because of the increasing of dipole-dipole interactions. The increase of capacity coefficients well correlates with the increase of of aminopyridines. The smaller capacity coefficient of 2- aminopyridine (pKa 6.67) in comparison with 3- aminopyridine (pKa 6.16) can be explained by steric hindrance of NH 2 -group. The greatest retention time of all model compounds was observed for the stationary phase containing pyridine as the modificator because of strong - Chromatogram of aminopyridine separation is presented on Figure 2. Figure 2. Chromatogram of separation of aminopyridines. Column 1 (1004,0 mm) . Mobile phase: hexane/i-propanol (90/10). Injection volume 20 l. 1 - 2-amino-5-chlorinepyridine; 2 - 2-amino-5-methylpyridine; 3 - 2-amino-4-methylpyridine; 4 – 2- aminopyridine. Figure 1. Layout view of the adsorption of modified gold nanoparticles on the silicon oxide’s surface. In order to estimate the retentive ability of prepared nanohybrid sorbents such model compounds as anilines, phenols, aminopyridines, some optically active compounds were used in normal-phase mode of HPLC. Previous research have shown that the optimum mobile phase was 90% hexane/10% isopropanol. It was found that Obtained results show that new nanohybrid materials based on stabilized by L-cystein, pyridine and citrate gold nanoparticles on silica surface are very perspective for further investigation. This work was supported by the Russian Foundation for Basic Research (09-03-00519-). *Corresponding author: irishan@mail.ru [1] M. Brust, M. Walker, D. Bethell, D. Schiffrin, R. Whyman, J. Chem. Soc., Chem. Commun., 801-802 (1994). [2] Kimling J., Maier M., Okenve B., Kotaidis V., Ballot H., Plech A., J. Phys. Chem. B. 110 15700 (2006). 6th Nanoscience and Nanotechnology Conference, zmir, 2010 216
Poster Session, Tuesday, June 15 Theme A1 - B702 L-cystein go ld nanoparticles on silica surface for HPLC separation Yana Elfimova 1 *, Irina Ananieva 1 , Aleksandr Majouga 1 , Nikolay Zyk 1 and Oleg Shpigun 1 1 Department of Chemistry, Lomonosov Moscow State University, Moscow, Russia Abstract-New nanohybrid material for HPLC based on gold nanoparticles supported on silica gel and stabilized by L-cystein is synthesized. The possibility of separation of -blockers and amino acids in different modes of chromatography is studied. Gold nanoparticles play an important role in applied science and technology because they exhibit unique chemical and physical properties which depend on their shape, size, and local environment [1]. Materials based on gold nanoparticles are widely used in the field of chemistry, biology, material science and physics. The dimensions of gold nanoparticles allow using them for the creation of a new class of separation materials for liquid chromatography. We suggest new sorbent based on the gold nanoparticles supported on silica gel and stabilized by L-cystein for the separation of different organic compounds including optically active compounds. Optically active compounds attract great attention because of their widespread application in many fields of science, particularly in pharmaceutics. Compounds that have optical isomers in many cases exhibit different pharmacological and toxicological properties. This fact has stimulated the application of enantiomerically pure products. -blockers play an important role among optically active compounds. -blockers are drugs that slow the heart rate, decrease cardiac output, lessen the force with which the heart muscle contracts and reduce blood vessel contraction. They do this by blocking beta-adrenergic receptors in various parts of the body. Another important class of optically active compounds is amino acids. Amino acids co-exist in biological liquids of living organisms though D- and L-isomers play different roles. That is why the problem of enantioseparation of different amino acids is very actual nowadays. HPLC has many applications in the fields of determination of amino acids. The commonly used method performance is the determination of amino acids as hydrophobic derivatives in reverse-phase mode on the hydrophobic stationary phase. In the present time much works in chiral separations have been directed to the development of new chiral selectors. Gold nanoparticles with average 10 nm size have been synthesized by reduction H[AuCl 4 ] in an aqua solution by sodium citrate, and then they have been modified by L-cystein. Prepared nanoparticles have been adsorbed on silica gel. The scheme of the synthesized stationary phase with L-cystein as organic lidand is presented on Fig.1. Obtained material has been tested for ability of -blockers and aminoacids. The best separation of aminopyridines was achieved in the normal-phase mode using 90% hexane/10% isopropanol as a mobile phase. The retention of aminopyridines rises with the growth of investigating compounds polarity because of the increasing of dipoledipole interactions. We studied t-blockers enantioseparation in normal-phase and polar-organic modes of chromatography. The best results were observed for pindolol at use of a mobile phase – acetonitrile / methanol / CH 3 COOH / triethylamine (60/40/0.2/0.2). The separation of amino acids was performed in the ion exchange variant of chromatography with spectrophotometric detection at 210 nm. We used 0.05M borate buffer (pH 7.7) as the mobile phase. Because a small molecule of L-cystein was used as a chiral selector the best enantioseparation was achieved for such a small molecules of amino acids as leucine and valine. Chromatogram of enantioseparation is presented on Fig.2. Figure 2. Chromatogram enantioseparation of pindolol. Column (100 . Mobile phase: acetonitrile/methanol/CH3COOH/threeethylamine (60/40/0,2/0,2). Injection volume 20 l. This work was supported by the Russian Foundation for Basic Research (09-03-00519-). *Corresponding author: elfimova_16@list.ru Figure 1. Layout view of the adsorption of modified gold nanoparticles on the silicon oxide’s surface. [1] A. Vasil’kov, S. Nikolaev, V. Smirnov, A. Naumkin, I. Volkov and V. Podshibikhin, Mendeleev Commun. 17, 268-270 (2007). 6th Nanoscience and Nanotechnology Conference, zmir, 2010 217
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