All Title Author
Keywords Abstract


Sol-Gel Thin Films Immobilized with Bromocresol Purple pH-Sensitive Indicator in Presence of Surfactants

DOI: 10.5402/2012/604389

Full-Text   Cite this paper   Add to My Lib

Abstract:

Preparation of transparent sol-gel thin film immobilized with bromocresol purple (BCP) pH-sensitive indicator was made via the acid catalyzed sol-gel reaction of tetraethylorthosilicate and the bromocresol purple indicator (BCP). Different surfactants include cationic cetyl trimethyl ammonium bromide (CTAB), anionic sodium dodecyl sulfate (SDS), and nonionic Triton X-100 (TX-100) were used to improve the mesostructure of the host material and to increase its porosity. The color change behavior of the immobilized bromocresol purple indicator affected significantly in presence of SDS comparing with its free counterpart in aqueous solution. In presence of CTAB and Triton-X 100, the immobilized bromocresol purple indicator shows similar behavior as its free counterpart in aqueous solution. The BCP retains its structure during the sol-gel reactions in terms of response to pH. Different parameters including concentration of indicator and surfactant, temperature, number of layers, response time, life time, and the number of measurements were investigated. The pKa values of the different prepared BCP immobilized thin films were determined. The BCP thin film sensor showed stability, repeatability, reproducibility, fast response, and long life time behavior. The polarized light microscopy indicated that the bromocresol purple indicator molecules are distributed uniformly within the host silica network. 1. Introduction Preparation of sol-gel matrices doped with some chemically and biologically active molecules is a promise route to chemical solid-state sensors [1–4]. The sol-gel technique is one of the most promising tools in material science. The term sol-gel refers to a chemical process where metallic or semimetallic alkoxide precursors or their derivatives form composites at moderate temperatures through a chemical reaction that involves hydrolysis followed by polycondensation [2]. Hydrolysis and polycondensation of tetraethoxysilane in presence of water, organic solvent, and an acid/base catalyst result in the formation of the –Si–O–Si– three-dimensional siloxane network [3–5]. The resulting matrix has high surface area, porosity, inertness, and stability to chemical and physical agents, and optical clarity in the visible and UV ranges [6–8]. Sol-gel matrices appear as a very important technique for immobilization, entrapment, encapsulation for large variety of materials such as organic, inorganic, and biomolecules [9, 10]. The sol-gel materials are ideal candidates as hosts for the analytical reagents because they are synthesized at low concentrations at the

References

[1]  W. Jin and J. D. Brennan, “Properties and applications of proteins encapsulated within sol-gel derived materials,” Analytica Chimica Acta, vol. 461, no. 1, pp. 1–36, 2002.
[2]  C. J. Brinker and G. W. Scherer, Sol-Gel Science, Academic Press, New York, NY, USA, 1990.
[3]  J. Livage, T. Coradin, and C. Roux, “Encapsulation of biomolecules in silica gels,” Journal of Physics Condensed Matter, vol. 13, no. 33, pp. R673–R691, 2001.
[4]  I. Gill and A. Ballesteros, “Bioencapsulation within synthetic polymers (Part 1): sol-gel encapsulated biologicals,” Trends in Biotechnology, vol. 18, no. 7, pp. 282–296, 2000.
[5]  X. Chen and S. Dong, “Sol-gel-derived titanium oxide/copolymer composite based glucose biosensor,” Biosensors and Bioelectronics, vol. 18, no. 8, pp. 999–1004, 2003.
[6]  X. Chen, Y. Hu, and G. S. Wilson, “Glucose microbiosensor based on alumina sol-gel matrix/electropolymerized composite membrane,” Biosensors and Bioelectronics, vol. 17, no. 11-12, pp. 1005–1013, 2002.
[7]  A. F. Hsu, T. A. Foglia, and S. Shen, “Immobilization of Pseudomonas cepacia lipase in a phyllosilicate sol-gel matrix: effectiveness as a biocatalyst,” Biotechnology and Applied Biochemistry, vol. 31, no. 3, pp. 179–183, 2000.
[8]  R. Zusman, C. Rottman, M. Ottolenghi, and D. Avnir, “Doped sol-gel glasses as chemical sensors,” Journal of Non-Crystalline Solids, vol. 122, no. 1, pp. 107–109, 1990.
[9]  L. L. Hench and J. K. West, “The sol-gel process,” Chemical Reviews, vol. 90, no. 1, pp. 33–72, 1990.
[10]  S. Sakka, in Sol-gel technology for thin films, fibers, electronics, and specialty shapes, L. C. Klein, Ed., p. 140, Noyes Publications, Park Ridge, NJ, USA, 1988.
[11]  R. D. Wilken, “Mercury analysis: a special example of species analysis,” Fresenius' Journal of Analytical Chemistry, vol. 342, no. 10, pp. 795–801, 1992.
[12]  J. D. Wright and N. A. J. M. Sommerdijk, Sol-Gel Materials: Chemistry and Applications, Gordon and Breach Science, Amsterdam, The Netherlands, 2001.
[13]  J. Samuel, A. Strinkovski, S. Shalom et al., “Miniaturization of organically doped sol-gel materials: a microns-size fluorescent pH sensor,” Materials Letters, vol. 21, no. 5-6, pp. 431–434, 1994.
[14]  F. R. Zaggout, “Entrapment of phenol red pH indicator into a sol-gel matrix,” Materials Letters, vol. 60, no. 8, pp. 1026–1030, 2006.
[15]  I. M. El-Nahhal, S. M. Zourab, and N. M. El-Ashgar, “Encapsulation of phenolphthalein pH-indicator into a sol-gel matrix,” Journal of Dispersion Science and Technology, vol. 22, no. 6, pp. 583–590, 2001.
[16]  Y. Dimitriev, Y. Ivanova, and R. Iordanova, “History of sol-gel science and technology,” Journal of the University of Chemical Technology and Metallurgy, vol. 43, no. 2, pp. 181–192, 2008.
[17]  O. S. Wolfbeis, N. V. Rodriguez, and T. Werner, “LED-compatible fluorosensor for measurement of near-neutral pH values,” Mikrochimica Acta, vol. 108, no. 3-6, pp. 133–141, 1992.
[18]  L. A. Saari and W. R. Seitz, “pH sensor based on immobilized fluoresceinamine,” Analytical Chemistry, vol. 54, no. 4, pp. 821–823, 1982.
[19]  A. Lobnik, I. Oehme, I. Murkovic, and O. S. Wolfbeis, “pH optical sensors based on sol-gels: chemical doping versus covalent immobilization,” Analytica Chimica Acta, vol. 367, no. 1–3, pp. 159–165, 1998.
[20]  L. M. Ellerby, C. R. Nishida, F. Nishida et al., “Encapsulation of proteins in transparent porous silicate glasses prepared by the sol-gel method,” Science, vol. 255, no. 5048, pp. 1113–1115, 1992.
[21]  G. Wirnsberger, P. Yang, B. J. Scott, B. F. Chmelka, and G. D. Stucky, “Mesostructured materials for optical applications: from low-k dielectrics to sensors and lasers,” Spectrochimica Acta Part A, vol. 57, no. 10, pp. 2049–2060, 2001.
[22]  I. M. El-Nahhal, S. M. Zourab, F. S. Kodeh, and A. Al-Bawab, “Behaviour of phenol red pH-sensors in the presence of different surfactants using the sol-gel process,” International Journal of Environmental Analytical Chemistry, vol. 90, no. 8, pp. 644–656, 2010.
[23]  G. G. Guilbality, Analytical Uses of Immobilized Enzymes, Marcel Dekker, New York, NY, USA, 1989.

Full-Text

comments powered by Disqus

Contact Us

service@oalib.com

QQ:3279437679

微信:OALib Journal