Doped sol-gel glasses as chemical sensors

Zusman, Rivka; Rottman, Claudio; Ottolenghi, Michael; Avnir, David

doi:10.1016/0022-3093(90)90232-b

Cited by 211 publications

(74 citation statements)

References 13 publications

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“…It is known that Soret band of porphyrin is extremely sensitive to dimerization and that free-base porphyrin in water solutions are in monomer form in a concentration range of 10 − 5 mol dm − 3 [31][32][33]. With the assumption that in aged aerogel pores only monomers and bands Q y (1,0) and Q y(0,1) are blue shifted while bands Q x (1,0) and Q x(0,1) are red shifted. These results were interpreted as arising from the less polar silica matrix, which consisted of Si-O -Si and Si -O groups what was observed for the octaethyl porphyrin in the earlier report [11].…”

Section: Resultsmentioning

confidence: 99%

“…The entrapment of organic reagents into sol -gel matrices and coatings has been the objective of much research since Avnir and co-workers pointed out the role of such systems for sensing purposes [1]. Sol -gel monoliths and sol -gel thin films are very useful to encapsulate various guests such as inorganic clusters [2][3][4], lanthanide complexes [5,6], laser dyes [7,8] and bioactive molecules [9,10].…”

Section: Introductionmentioning

confidence: 99%

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Spectroscopic characterization of water-soluble cationic porphyrins in sol–gel silica matrices and coatings

Dargiewicz¹,

Makarska²,

Radzki³

2002

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Silica aeorogels doped with different concentrations of water-soluble cationic porphyrins were synthesised by the sol-gel polymerisation of tetraethylorthosilicate (TEOS). Porphyrin dimer formation in sol-gel matrices was studied in the function of gelation time, over the porphyrin concentration range up to 10 − 5 M. The deviation from the linearity of Beer-Lambert law starts with porphyrin concentration about 5 ×10 − 6 M. The dimerization constants were estimated. The similar dependence could be observed for the aerogels and the solid thin films.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spectroscopic characterization of water-soluble cationic porphyrins in sol–gel silica matrices and coatings

Dargiewicz¹,

Makarska²,

Radzki³

2002

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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show abstract

“…Surfactants were used considerably in recent years to form mesostructures of silica matrix and so high porosity silica was obtained that host sensing molecules efficiently [12,13,22]. Recently sol-gel thin films were useful to encapsulate many active molecules such as inorganic clusters, porphyrins, photochromic and laser dyes, rare earth complexes, bioactive molecules, and so forth, that were mainly obtained for sensing purposes [6][7][8][9][10][11][12][13][14][15].…”

Section: Isrn Analytical Chemistrymentioning

confidence: 99%

“…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-threedimensional siloxane network [3][4][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][7][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].…”

Section: Introductionmentioning

confidence: 99%

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

El‐Ashgar

El-Basioni

El‐Nahhal

et al. 2012

ISRN Analytical Chemistry

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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 pK a 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.

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“…Sol gel solution and thin films were prepared as already described [7,19,20]. Briefly, a tetraethoxysilane (TEOS, 98%, ABCR Co., Germany) precursor was used as bulk sol-gel solution.…”

Section: Sol-gel Thin Filmsmentioning

confidence: 99%

Effects of Physical Parameters on Bacterial Cell Adsorption onto Pre-Imprinted Sol-Gel Films

Starosvetsky¹,

Cohen²,

Cheruti³

et al. 2012

JBNB

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Organically modified silica (ORMOSILS) thin films produced by sol-gel method were imprinted with two bacterial strains as whole cells in order to develop an easy, fast and specific probe to detect and specifically identify these microorganisms when present in water samples. An important feature of the imprinting process was the molecular fingerprints left by these microorganisms alongside morphology, into imprinted film cavities. The films also showed high selectivity toward the imprinted template and were able to discriminate between two very close bacterial species (E. coli and S. typhimurium). In addition, several central physical parameters of the experimental water solution were examined (i.e., pH, ionic strength and the organic load exemplified by NaCl and TOC concentration, respectively). The method sensitivity to different bacterial concentrations was studied by confocal microscopy (CLSM) and quartz crystal microbalance (QCM) tools. Results showed that increased bacterial concentrations favor rapid adsorption onto imprinted sol-gel films with high affinity, while low pH, increased organic load and high ionic concentrations (i.e., seawater) interfere with bacteria re-adsorption, reducing detection capability. Under average drinking water chemical composition the method proved to be highly efficient.

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Doped sol-gel glasses as chemical sensors

Cited by 211 publications

References 13 publications

Spectroscopic characterization of water-soluble cationic porphyrins in sol–gel silica matrices and coatings

Spectroscopic characterization of water-soluble cationic porphyrins in sol–gel silica matrices and coatings

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

Effects of Physical Parameters on Bacterial Cell Adsorption onto Pre-Imprinted Sol-Gel Films

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