engleski

Sol-Gel Thin Films Doped With Bromocresol Green Indicator As pH Responsive Organic-Inorganic Hybrid Materials

Sol-gel glasses are widely employed as immobilisation matrices for chemical and biochemical reagents used in chemical sensors. Sol-gel technology allows low-temperature preparation of optically transparent porous thin films with tunable properties making them particularly suitable for development of optical sensors. The most often used sol-gel precursors for preparation of inorganic silicate glass matrices are tetramethoxysilane (TMOS) and tetraethoxysilane (TEOS). Introduction of organic functional groups into inorganic precursors and their co-polymerisation with TEOS or TMOS results in inorganic/organic hybrid materials or Ormosils (organically modified silicates). In this work we studied the effects of organic modification of silicate matrix on physical and mechanical properties, as well as pH sensing performance of thin films containing entrapped pH colorimetric indicator Bromocresol Green (BCG). TEOS and organically modified sol-gel precursor, glycidoxypropyltrimethoxysilane (GLYMO), were used as precursors in different proportions along with surfactant molecules to obtain matrices of different properties. The effects of film composition on the UV-Vis spectral properties and the film analytical performance (apparent pKa value, response time, reversibility) have been studied. Feasibility of use of GLYMO/TEOS based sol gel hybrids as potentially attractive materials for preparation of optical pH sensors and pH based biosensors has been performed.

Sol-gel technology; optical sensors

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