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

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]  I. M. El-Nahhal,et al.  Behaviour of phenol red pH-sensors in the presence of different surfactants using the sol-gel process , 2010 .

[2]  Y. Dimitriev,et al.  History of Sol—Gel Science and Technology , 2009 .

[3]  F. R. Zaggout.  Entrapment of phenol red pH indicator into a sol–gel matrix , 2006 .

[4]  Shaojun Dong,et al.  Sol-gel-derived titanium oxide/copolymer composite based glucose biosensor. , 2003, Biosensors & bioelectronics.

[5]  G. S. Wilson,et al.  Glucose microbiosensor based on alumina sol-gel matrix/electropolymerized composite membrane. , 2002, Biosensors & bioelectronics.

[6]  John D. Brennan,et al.  Properties and applications of proteins encapsulated within sol–gel derived materials , 2002 .

[7]  G. Stucky,et al.  Mesostructured materials for optical applications: from low-k dielectrics to sensors and lasers. , 2001, Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy.

[8]  I. M. El-Nahhal,et al.  Encapsulation of Phenolphthalein pH-Indicator into a Sol-Gel Matrix , 2001 .

[9]  Thibaud Coradin,et al.  Encapsulation of biomolecules in silica gels , 2001 .

[10]  John D. Wright,et al.  Sol-Gel Materials , 2000 .

[11]  A. Ballesteros,et al.  Bioencapsulation within synthetic polymers (Part 1): sol-gel encapsulated biologicals. , 2000, Trends in biotechnology.

[12]  T. Foglia,et al.  Immobilization of Pseudomonas cepacia lipase in a phyllosilicate sol–gel matrix: effectiveness as a biocatalyst , 2000, Biotechnology and applied biochemistry.

[13]  Aleksandra Lobnik,et al.  pH optical sensors based on sol–gels: Chemical doping versus covalent immobilization , 1998 .

[14]  Joshua Samuel,et al.  Miniaturization of organically doped sol-gel materials: a microns-size fluorescent pH sensor , 1994 .

[15]  R. Wilken.  Mercury analysis: a special example of species analysis , 1992 .

[16]  Otto S. Wolfbeis,et al.  LED-compatible fluorosensor for measurement of near-neutral pH values , 1992 .

[17]  J S Valentine,et al.  Encapsulation of proteins in transparent porous silicate glasses prepared by the sol-gel method. , 1992, Science.

[18]  Larry L. Hench,et al.  The sol-gel process , 1990 .

[19]  Claudio Rottman,et al.  Doped sol-gel glasses as chemical sensors , 1990 .

[20]  George G. Guilbault,et al.  Analytical Uses of Immobilized Enzymes , 1984 .

[21]  W. Rudolf Seitz,et al.  pH sensor based on immobilized fluoresceinamine , 1982 .

[22]  C. Brinker.  Sol-gel science , 1990 .