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Optical Fiber Element of Sensors with Biolumiscent Cells
Vrbová, Hana ; Kuncová, Gabriela ; Pospíšilová, Marie
In this work, we compared theoretical calculations [2] of coupling efficiency with experiments for various OFEs with the immobilized whole-cell bacterial bioreporter of Pseudomonas fluorescens HK44 (producing bioluminescence in presence of naphthalene and salicylate). We evaluated the influence of the physical properties and geometry of the OFE, active layer and cell immobilization techniques on intensity of detected light.
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pH Responsive Sol-Gel Hybrid Materials Doped With Colorimetric Sulfonphtalein pH Indicators
Frančič, N. ; Rychtáriková, Renata ; Kuncová, Gabriela ; Lobnik, A.
In this work, we have studied the effects of epoxy-modifications on functional properties organic-inorganic materials prepared by copolymerization of 3-glycidoxypropyl trimethoxysilane (GPTMS) a tetramethoxysilane (TMOS) with entrapped pH colorimetric indicators. Results show that the dyes are completely physically entrapped with no leaching. Sensor membranes have dynamic ranges from pH 3 - 7 (bromocresol green), pH 5 - 8 (bromocresol purple), pH 6 - 10 (bromothymol blue), and pH 2 - 5 (bromofenol blue), respectively. Thin films show excellent reproducibility, reversibility and have short response times of 200 s. We have also determined that the lower molar ratio of TMOS gave us better responses to pH changes, while the higher TMOS ratio gave us more uniform layers. The best overall results were obtained by molar ratio 5.67:1 of GPTMS and TMOS.
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Optical Absorption Sensors for Evaluation of Yeast Acidification Power
Rychtáriková, Renata ; Frančič, N. ; Hetflejš, Jiří ; Kuncová, Gabriela ; Gabriel, P. ; Lobnik, A.
The acidification power test provides a fast and simple method of assessing the ability of cells to perform a successful fermentation. It has been used as a rejection criterion for assessing the technological quality of starter yeast cultures in brewing, cider production, baking, as well as cheese making based on lactic acid bacteria. The cell acidification power responses to pH decrease of the environment after glucose addition. We have prepared novel recognition elements of pH sensors suitable for evaluation of yeast acidification power by absorption of two pH sensitive sulfonphthalein dyes (bromocresol green and bromophenol blue) into hydrogel of poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate). The absorption spectra, function ranges, pKa values, and response times for each absorbed dye were evaluated, compared with the free dyes, and further discussed with regard to its application to the acidification power test.
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