Poly(dimethylsiloxane) as a pre-coating in layer-by-layer films containing phosphotungstate nanoclusters electrochemically sensitive toward s-triazines

One of the major advantages of the Layer-by-Layer (LbL) deposition technique is the possible control of molecular architecture, not only to achieve optimized properties but also to seek synergy among different materials. In this study, LbL films containing nanoclusters of a Keggin type polyoxometalate, phosphotungstic acid (HPW), alternated with the polycation poly(allylamine hydrochloride) (PAH) were deposited on indium-tin oxide (ITO) substrates. The electrochemical properties of the hybrid LbL film investigated in acidic conditions indicated no significant desorption of HPW, when a layer of poly(dimethylsiloxane) terminated with 3-aminopropyl groups (PDMS) was previously deposited on the ITO substrate. Such effect occurred because PDMS prevents desorption of HPW from the hybrid film, as shown by X-ray Photoelectron Spectroscopy (XPS) analyses. The porous structures of the films were revealed by Fourier transform infrared reflection absorption spectroscopy, scanning electron microscopy and XPS. PDMS/PAH as a pre-coating allowed the HPW/PAH films to be sensitive to the electrochemical detection of the triazines atrazine and melamine. In conclusion, the precise control of the LbL films architecture is important to develop opportunities for new applications. © 2014 The Royal Society of Chemistry.One of the major advantages of the Layer-by-Layer (LbL) deposition technique is the possible control of molecular architecture, not only to achieve optimized properties but also to seek synergy among different materials. In this study, LbL films containin4562961229621FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORsem informaçãosem informaçãosem informaçãoDecher, G., (1997) Science, 277, p. 1232Stockton, W.B., Rubner, M.F., (1997) Macromolecules, 30, p. 2717Shimazaki, Y., Mitsuishi, M., Ito, S., Yamamoto, M., (1997) Langmuir, 13, p. 1385Kohli, P., Blanchard, G.J., (2000) Langmuir, 16, p. 8518Anzai, J., Kobayashi, Y., (2000) Langmuir, 16, pp. 2851-2856Shi, X., Shen, M., Mohwald, H., (2004) Prog. Polym. Sci., 29, p. 987Zucolotto, V., Ferreira, M., Cordeiro, M.R., Constantino, C.J.L., Moreira, W.C., Oliveira Jr., O.N., (2006) Sens. Actuators, B, 113, p. 809Alexeyeva, N., Tammeveski, K., (2008) Anal. Chim. Acta, 618, p. 140Liu, S., Volkmer, D., Kurth, D.G., (2003) J. Cluster Sci., 14, p. 405Kuhn, A., Mano, N., Vidal, C., (1999) J. Electroanal. Chem., 462, p. 187Cherstiouk, O.V., Simonov, A.N., Tsirlina, G.A., (2012) Electrocatalysis, 3, p. 230Lu, M., Lee, D., Xue, W., Cui, T., (2009) Sens. Actuators, A, 150, p. 280Han, B.H., Manners, I., Winnik, M.A., (2005) Chem. Mater., 17, p. 3160Perinotto, A.C., Caseli, L., Hayasaka, C.O., Riul Jr., A., Oliveira Jr., O.N., Zucolotto, V., (2008) Thin Solid Films, 516, p. 9002Moraes, M.L., De Souza, N.C., Hayasaka, C.O., Ferreira, M., Rodrigues-Filho, U.P., Riul Jr., A., Zucolotto, V., Oliveira Jr., O.N., (2009) Mater. Sci. Eng., C, 29, p. 442Liu, S., Mohwald, H., Volkmer, D., Kurth, D.G., (2006) Langmuir, 22, p. 1949Katsoulis, D.E., (1998) Chem. Rev., 98, p. 359Papaconstantinuou, E., (1989) Chem. Soc. Rev., 18, p. 1Timofeeva, M.N., (2003) Appl. Catal., A, 256, p. 19Sadakane, M., Steckhan, E., (1998) Chem. Rev., 98, p. 219Yamase, T., (1998) Chem. Rev., 98, p. 307De Oliveira Jr., M., Lopes De Souza, A., Schneider, J., Pereira Rodrigues-Filho, U., (2011) Chem. Mater., 23, p. 953Ferreira-Neto, E.P., De Carvalho, F.L.S., Ullah, S., Zoldan, V.C., Pasa, A.A., De Souza, A.L., Battirola, L.C., Rodrigues Filho, U.P., (2013) J. Sol-Gel Sci. Technol., 66, p. 363Souza, A.L., Marques, L.A., Eberlin, M.N., Nascente, P.A.P., Herrmann Jr., P.S.P., Leite, F.L., Rodrigues-Filho, U.P., (2012) Thin Solid Films, 520, p. 3574Liu, S., Tang, Z., (2010) Nano Today, 5, p. 267Dong, T., Ma, H., Zhang, W., Gong, L., Wang, F., Li, C., (2007) J. Colloid Interface Sci., 311, p. 523Ma, H., Dong, T., Wang, F., Zhang, W., Zhou, B., (2006) Electrochim. Acta, 51, p. 4965Cheng, L., Cox, J.A., (2002) Chem. Mater., 14, p. 6Gu, Y., Ma, H., O'Halloran, K.P., Shi, S., Zhang, Z., Wang, X., (2009) Electrochim. Acta, 54, p. 7194Kulesza, P.J., Chojak, M., Karnicka, K., Miecznikowski, K., Palys, B., Lewera, A., Wieckowski, A., (2004) Chem. Mater., 16, p. 4128Ernst, A.Z., Zoladek, S., Wiaderek, K., Cox, J.A., Kolary-Zurowska, A., Miecznikowski, K., Kulesza, P.J., (2008) Electrochim. Acta, 53, p. 3924Sun, L., Ca, D.V., Cox, J.A., (2005) J. Solid State Electrochem., 9, p. 816Liu, S., Kurth, D.G., Bredenkotter, B., Volkmer, D., (2002) J. Am. Chem. Soc., 124, p. 12279Cheng, L., Cox, J.A., (2001) Electrochem. Commun., 3, p. 285Feng, Y., Han, Z., Peng, J., Lu, J., Xue, B., Li, L., Ma, H., Wang, E., (2006) Mater. Lett., 60, p. 1588Xu, B., Xu, L., Gao, G., Jin, Y., (2007) Appl. Surf. Sci., 253, p. 3190Cheng, L., Dong, S., (2000) J. Electrochem. Soc., 147, p. 606Fernandes, D.M., Carapuça, H.M., Brett, C.M.A., Cavaleiro, A.M.V., (2010) Thin Solid Films, 518, p. 5881Cheng, L., Dong, S., (2000) J. Electroanal. Chem., 481, p. 168Liu, S., Volkmer, D., Kurth, D.G., (2004) Anal. Chem., 76, p. 4579Sosnowska, M., Goral-Kurbiel, M., Skunik-Nuckowska, M., Jurczakowski, R., Kulesza, P.J., (2013) J. Solid State Electrochem., 17, p. 1631Layla Mehdi, B., Rutkowska, I.A., Kulesza, P.J., Cox, J.A., (2013) J. Solid State Electrochem., 17, p. 1581Shiu, K.-K., Anson, F.C., (1991) J. Electroanal. Chem., 309, p. 115Martel, D., Kuhn, A., (2000) Electrochim. Acta, 45, p. 1829Chan, Z.C.Y., Lai, W.-F., (2009) Trends Food Sci. Technol., 20, p. 366Gammon, D.W., Aldous, C.N., Carr Jr., W.C., Sanborn, J.R., Pfeifer, K.F., (2005) Pest Manage. Sci., 61, p. 331Yu, J., Zhang, C., Dai, P., Ge, S., (2009) Anal. Chim. Acta, 651, p. 209Shoji, R., Takeuchi, T., Kubo, I., (2003) Anal. Chem., 75, p. 4882Donley, C., Dunphy, D., Paine, D., Carter, C., Nebesny, K., Lee, P., Alloway, D., Armstrong, N.R., (2002) Langmuir, 18, p. 450Sawyer, D.T., Sobkowiak, A., Roberts Jr., J.L., (1995) Electrochemistry for Chemists, pp. 68-78. , John Wiley & Sons, New York, 2nd edn, ch. 3Beamson, G., Briggs, D., (1992) High Resolution of XPS of Organic Polymers: The Scienta ESCA 300 Database, , John Wiley & Sons, ChichesterPope, M.T., Varga Jr., G.M., (1966) Inorg. Chem., 5, p. 1249Keita, B., Nadjo, L., (1987) J. Electroanal. Chem., 227, p. 77Stotter, J., Show, Y., Wang, S., Swain, G., (2005) Chem. Mater., 17, p. 4880Senthilkumar, M., Mathiyarasu, J., Joseph, J., Phani, K.L.N., Yegnaraman, V., (2008) Mater. Chem. Phys., 108, p. 403Vanleugenhague, C., Pourbaix, M., (1966) Atlas of Electrochemical Equilibra in Aqueous Solution, pp. 436-442. , ed. M. Pourbaix, Pergamon Press, OxfordDeltombe, E., De Zoubov, N., Vanleugenhague, C., Pourbaix, M., (1966) Atlas of Electrochemical Equilibra in Aqueous Solution, pp. 475-484. , ed. M. Pourbaix, Pergamon Press, OxfordPope, M.T., (1987) Comprehensive Coordination Chemistry, 3, p. 1039. , ed. G. Wilkinson, R. D. Gillard and J. A. McCleverty, Plenum Press, New YorkAkhtar, M.S., Cheralathan, K.K., Chun, J.M., Yang, O.B., (2008) Electrochim. Acta, 53, p. 6623Oliveira, F.C., Schneider, J., Siervo, A., Landers, R., Plepis, A.M.G., Pireaux, J.J., Rodrigues-Filho, U.P., (2002) Surf. Interface Anal., 34, p. 580Zhang, L., Jin, Q., Huang, J., Liu, Y., Shan, L., Wang, X., (2010) Appl. Surf. Sci., 256, p. 5911(2011) X-Ray Photoelectron Spectroscopy Database, Standard Database 20, Version 3.5, , http://srdata.nist.gov/xps/Version_his.aspxNunes De Carvalho, C., Botelho Do Rego, A.M., Amaral, A., Brogueira, P., Lavareda, G., (2000) Surf. Coat. Technol., 124, p. 70Lourenço, J.M.C., Ribeiro, P.A., Botelho Do Rego, A.M., Braz Fernandes, F.M., Moutinho, A.M.C., Raposo, M., (2004) Langmuir, 20, p. 8103Liu, Y.T., Deng, J., Xiao, X.L., Ding, L., Yuan, Y.L., Li, H., Li, X.T., Wang, L.L., (2011) Electrochim. Acta, 56, p. 4595Liao, C.W., Chen, Y.-R., Chang, J.-L., Zen, J.-M., (2011) J. Agric. Food Chem., 59, p. 9782Akter, H., Shaikh, A.A., Chowdhury, T.R., Rahmam, M.S., Bakshi, P.K., Saleh Ahammad, A.J., (2013) ECS Electrochem. Lett., 2 (8), p. 13Tran, H.V., Yougnia, R., Reisberg, S., Piro, B., Serradji, N., Nguyen, T.D., Tran, L.D., Pham, M.C., (2012) Biosens. Bioelectron., 31, p. 62Norouzi, P., Larijani, B., Ganjali, M.R., Faridbod, F., (2012) Int. J. Electrochem. Sci., 7, p. 10414Xu, G., Zhang, H., Zhong, M., Zhang, T., Lu, X., Kan, X., (2014) J. Electroanal. Chem., 713, p. 112Pesavento, M., D'Agostino, G., Biesuz, R., Alberti, G., (2009) Electroanalysis, 21, p. 604Svorc, L., Rievaj, M., Bustin, D., (2013) Sens. Actuators, B, 181, p. 294This work was supported by FAPESP, CNPq, CAPES and Brazilian Network nBioNe

The Combinatorics of Alternating Tangles: from theory to computerized enumeration

We study the enumeration of alternating links and tangles, considered up to topological (flype) equivalences. A weight $n$ is given to each connected component, and in particular the limit $n\to 0$ yields information about (alternating) knots. Using a finite renormalization scheme for an associated matrix model, we first reduce the task to that of enumerating planar tetravalent diagrams with two types of vertices (self-intersections and tangencies), where now the subtle issue of topological equivalences has been eliminated. The number of such diagrams with $p$ vertices scales as $12^p$ for $p\to\infty$. We next show how to efficiently enumerate these diagrams (in time $\sim 2.7^p$) by using a transfer matrix method. We give results for various generating functions up to 22 crossings. We then comment on their large-order asymptotic behavior.Comment: proceedings European Summer School St-Petersburg 200

Peptide immobilisation on porous silicon surface for metal ions detection

In this work, a Glycyl-Histidyl-Glycyl-Histidine (GlyHisGlyHis) peptide is covalently anchored to the porous silicon PSi surface using a multi-step reaction scheme compatible with the mild conditions required for preserving the probe activity. In a first step, alkene precursors are grafted onto the hydrogenated PSi surface using the hydrosilylation route, allowing for the formation of a carboxyl-terminated monolayer which is activated by reaction with N-hydroxysuccinimide in the presence of a peptide-coupling carbodiimide N-ethyl-N'-(3-dimethylaminopropyl)-carbodiimide and subsequently reacted with the amino linker of the peptide to form a covalent amide bond. Infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy are used to investigate the different steps of functionalization

Histoire médicale générale et particulière des maladies épidémiques, contagieuses et épizootiques, qui ont régné en Europe depuis les temps les plus reculés jusqu'a nos jours /

Europeana-GoogleBook

The critical role of wavelength in the UV-activated grafting of 1-alkene onto silicon and silicon nitride Si x N 4 surfaces

International audienc

Experimental study of macropore formation in p-type silicon in a fluoride solution and the transition between macropore formation and electropolishing

Anodic dissolution of p-Si is studied in diluted fluoride solution (HF 0.05M+NH4F 0.05 M, pH 3), with special focus on the physico-chemical parameters which govern the morphology of pore formation (crystallographic orientation, applied potential, and etching time). The effect of potential has been investigated in the transition region between macropore formation and electropolishing.Upon increasing the anodization potential, the pore cross-section changes from circular to square shape, and the bottom of the pores changes from a rounded to a V-shaped profile. Prolonged etching of the contour of (1 1 0) p-Si disks in the regime of porous silicon formation allows for a comparison of the etching characteristics of the (1¯1x) orientations. SEM observation indicates indeed different morphologies as a function of the crystal orientation, and the formation of fractal-like structures is obtained for some orientations. In the same geometry and at a potential just above the onset of the electropolishing regime, prolonged anodization allows for a direct measurement of the Si thickness removed as a function of the crystallographic orientation. We clearly observe the etching anisotropy, with etch depth (111) < (110) < (1 0 0). This sequence, similar to that observed for current density in more concentrated HF, differs from that observed for the chemical etching of Si in an alkaline solutio