Papers by Gabriela Kuncova
Chemicke Listy, 2014
Transesterification of soybean oil (O) with glycerol (G), catalysed by Novozym 435, was studied i... more Transesterification of soybean oil (O) with glycerol (G), catalysed by Novozym 435, was studied in tert-butyl alcohol as solvent. The effects of reaction tempe¬rature (4050 °C), solvent concentration (2035 vol.%), G/O molar ratio (1:1 2:1), and residence time (min) on the oil phase composition (tri- (TAG), di- (DG) and monoacylglycerol) were evaluated. DAG formation was preferred at lower temperatures, lower G/S mole ratios, and at higher solvent concentrations. The data for G/S = 2:1 agreed well with those obtained in a continous fixed-bed column reactor. Glycerolyses of olive, sunflower, rapeseed, and linseed oils are also reported. Higher reaction rates of continous processes compared with batch glycero¬lysis were observed.
Optical fibre biosensor for oxygen and glucose monitoring based on Ruthenium/ORMOCER/Enzyme layers
Sensors, 2020
In this study, we show the repetitive detection of toluene on a tapered optical fiber element (OF... more In this study, we show the repetitive detection of toluene on a tapered optical fiber element (OFE) with an attached layer of Pseudomonas putida TVA8 bioluminescent bioreporters. The bioluminescent cell layer was attached on polished quartz modified with (3-aminopropyl)triethoxysilane (APTES). The repeatability of the preparation of the optical probe and its use was demonstrated with five differently shaped OFEs. The intensity of measured bioluminescence was minimally influenced by the OFE shape, possessing transmittances between 1.41% and 5.00%. OFE probes layered with P. putida TVA8 were used to monitor liquid toluene over a two-week period. It was demonstrated that OFE probes layered with positively induced P. putida TVA8 bioreporters were reliable detectors of toluene. A toluene concentration of 26.5 mg/L was detected after <30 min after immersion of the probe in the toluene solution. Additional experiments also immobilized constitutively bioluminescent cells of E. coli 652T7...
Sensors, 2021
Glucose belongs among the most important substances in both physiology and industry. Current food... more Glucose belongs among the most important substances in both physiology and industry. Current food and biotechnology praxis emphasizes its on-line continuous monitoring and regulation. These provoke increasing demand for systems, which enable fast detection and regulation of deviations from desired glucose concentration. We demonstrated control of glucose concentration by feedback regulation equipped with in situ optical fiber glucose sensor. The sensitive layer of the sensor comprises oxygen-dependent ruthenium complex and preimmobilized glucose oxidase both entrapped in organic–inorganic polymer ORMOCER®. The sensor was placed in the laboratory bioreactor (volume 5 L) to demonstrate both regulations: the control of low levels of glucose concentrations (0.4 and 0.1 mM) and maintenance of the glucose concentration (between 2 and 3.5 mM) during stationary phase of cultivation of Saccharomyces cerevisiae. Response times did not exceed 6 min (average 4 min) with average deviation of 4%....
Sensors, 2020
Mercury is a ubiquitous environmental pollutant of dominantly anthropogenic origin. A critical co... more Mercury is a ubiquitous environmental pollutant of dominantly anthropogenic origin. A critical concern for human health is the introduction of mercury to the food chain; therefore, monitoring of mercury levels in agricultural soil is essential. Unfortunately, the total mercury content is not sufficiently informative as mercury can be present in different forms with variable bioavailability. Since 1990, the use of bioreporters has been investigated for assessment of the bioavailability of pollutants; however, real contaminated soils have rarely been used in these studies. In this work, a bioassay with whole-cell bacterial bioreporter Escherichia coli ARL1 was used for estimation of bioavailable concentration of mercury in 11 soil samples. The bioreporter emits bioluminescence in the presence of Hg(II). Four different pretreatments of soil samples prior to the bioassay were tested. Among them, laccase mediated extraction was found to be the most suitable over water extraction, alkalin...
Enzyme Immobilised Coatings for Glucose Optical Fibre Sensors
Optical Fiber Sensors, 2006
Page 1. Enzyme Immobilised Coatings for Glucose Optical Fibre Sensors PJScully1 , JSYoung1, O. Po... more Page 1. Enzyme Immobilised Coatings for Glucose Optical Fibre Sensors PJScully1 , JSYoung1, O. Podrazky2,3, G. Kuncova2, J. Bolyo2, V. Matejec3, K. Rose4, L. Sasek5, N. Jaffrezic-Renault6, SV Dzyadevych6,7, R. Fernandez-Lafuente8, L. Betancor8, BO'Kennedy9. ...
Optical fibre biosensors using enzymatic transducers to monitor glucose
Measurement Science and Technology, 2007
The construction and performance of a novel enzyme based optical sensor for in situ continuous mo... more The construction and performance of a novel enzyme based optical sensor for in situ continuous monitoring of glucose in biotechnological production processes is presented. Sensitive optical coatings are formed from inorganic-organic hybrid polymers (ORMOCER®sORMOCER®: Trademark of Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e. V. in Germany.) combined with a flurophore (ruthenium complex) and an enzyme, and applied to lenses, declad
Materials Science and Engineering: C, 2002
The use of a sensor employing a short, straight segment of a silica fiber with an inverted parabo... more The use of a sensor employing a short, straight segment of a silica fiber with an inverted parabolic refractive index profile in the core for the detection of aqueous solutions of toluene was investigated. The sensing layer of the fiber was prepared by depositing a thin polydimethylsiloxane layer on the bare fiber core by the dip-coating technique. The performance of the fiber was examined in relatively long static and dynamic exposures of the fiber to toluene solutions, during which saturated values of the output sensor signal were reached. Detection sensitivities of several milligrams per liter were achieved for both types of exposures.
Journal of Sol-Gel Science and Technology, 2012
5,10,15,20-Tetrakis(4-sulfonatophenyl)porphyrin was entrapped into biocompatible hydrogels formed... more 5,10,15,20-Tetrakis(4-sulfonatophenyl)porphyrin was entrapped into biocompatible hydrogels formed by self-assembling micelles of the titanium dioxide prepared by hydrolysis of titanium ethoxide modified with triethanolamine (TEA). The materials were characterized by their optical and photosensitive properties. The immobilization led to changes of the absorption spectra of the dye and decreased its molar absorption coefficient. The TiO 2 matrix did not degrade the entrapped porphyrin upon u.v. irradiation. The formation of TEA-titanium(IV) chelates facilitated a controlled and triggered release of the immobilized dye from the hydrogels in lactate and citrate buffers. The released dye prolonged the sterility of citrate-phosphate buffer and its illumination with visible light inhibited growth of Aspergillus niger.
Hybrid coatings as transducers in optical biosensors
Journal of Coatings Technology and Research, 2008
Sensitive coatings are described for a novel enzyme-based optical sensor for in-situ continuous m... more Sensitive coatings are described for a novel enzyme-based optical sensor for in-situ continuous monitoring of reactants, such as glucose, in biotechnological production processes. Glucose oxidase, incorporated into suitable coating materials that are applied on lenses or optical fibers, is used to catalyze oxidization of glucose to gluconic acid in the presence of oxygen. The presence and consumption of oxygen is
The use of silica gel prepared by sol-gel method and polyurethane foam as microbial carriers in the continuous degradation of phenol
Applied Microbiology and Biotechnology, 2000
A mixed microbial culture was immobilized by entrapment into silica gel (SG) and entrapment/ adso... more A mixed microbial culture was immobilized by entrapment into silica gel (SG) and entrapment/ adsorption on polyurethane foam (PU) and ceramic foam. The phenol degradation performance of the SG biocatalyst was studied in a packed-bed reactor (PBR), packed-bed reactor with ceramic foam (PBRC) and fluidized-bed reactor (FBR). In continuous experiments the maximum degradation rate of phenol (q(s)max) decreased in the order: PBRC (598 mg l(-1) h(-1)) &gt; PBR (PU, 471 mg l(-1)h(-1)) &gt; PBR(SG, 394 mg l(-1) h(-1)) &gt; FBR (PU, 161 mg l(-1) h(-1)) &gt; FBR (SG, 91 mg l(-1) h(-1)). The long-term use of the SG biocatalyst in continuous phenol degradation resulted in the formation of a 100-200 microm thick layer with a high cell density on the surface of the gel particles. The abrasion of the surface layer in the FBR contributed to the poor degradation performance of this reactor configuration. Coating the ceramic foam with a layer of cells immobilized in colloidal SiO2 enhanced the phenol degradation efficiency during the first 3 days of the PBRC operation, in comparison with untreated ceramic packing.
This work deals with changes in microbial phenol degradation and cell proliferation caused by imm... more This work deals with changes in microbial phenol degradation and cell proliferation caused by immobilization into silica gel. Mixed microbial culture and the yeast Candida tropicalis were immobilized in silica layers and pieces prepared by mixing of prepolymerized tetraethoxysilane with cell suspension. The phenol degradation rate of cells entrapped in silica gel was compared with those immobilized into an organic polymer-polyurethane. The phenol degradation efficiency decreased in the following order: free cell suspension > cells entrapped into polyurethane foam > cells entrapped into prepolymerized TEOS. Inside the silica there was no growth observed by optical microscope. The immobilization of bacterium Pseudomonas species 2 into silica gel, cells which cometabolize PCBs with biphenyl, did not result in substantial change of intermediate concentration.
Effect of preparation of sol-gel coatings on the strength of optical fibres
Journal of Sol-Gel Science and Technology, 1995
... Fibres VLASTIMIL MATEJEC, M/LOS HAYER, PETER PAVLOVIC AND MARTA KUBE(~KOV/k Institute of the ... more ... Fibres VLASTIMIL MATEJEC, M/LOS HAYER, PETER PAVLOVIC AND MARTA KUBE(~KOV/k Institute of the Radio Engineering and Electronics, Academy of Sciences of Czech Republic, Chaberskd 57, 182 51 Praha 8 GABRIELA ...
Whole-cell detectors of contaminants constructed by immobilization of bioreporters in form of biofilm on special optical fiber elements
2019 IEEE International Conference on Sensors and Nanotechnology, 2019
A whole-cell optical fiber sensor of toluene was prepared by the adsorption of Pseudomonas putida... more A whole-cell optical fiber sensor of toluene was prepared by the adsorption of Pseudomonas putida TVA8, the bacterial strain producing light in contact with toluene, in the form of biofilm. Bioreporter immobilization was facilitated by (3-Aminopropyl)triethoxysilane (APTES) treatment on the wider end of tapered quartz optical fiber element (OFE). Repeatability of preparation and response of the active part of the biosensor was demonstrated in five trials with different OFE geometries in which the bioluminescence (BL) was induced with toluene solution (26.5 mg L−1) for 2 weeks. Longevity of inductions of the biosensor was shown in over 135 days trial, when the biosensor was repetitively induced with toluene solution (26.5 mg L−1) 68 times. The intensities of BL gradually decreased due to release of the adsorbed cells and they were only temporarily restored by the addition of nutrients. The intensities of BL induced with contaminated ground water were lower than in the mineral medium ...
Materials, 2016
Living cells of the lux-based bioluminescent bioreporter Pseudomonas putida TVA8 were encapsulate... more Living cells of the lux-based bioluminescent bioreporter Pseudomonas putida TVA8 were encapsulated in a silica hydrogel attached to the distal wider end of a tapered quartz fiber. Bioluminescence of immobilized cells was induced with toluene at high (26.5 mg/L) and low (5.3 mg/L) concentrations. Initial bioluminescence maxima were achieved after >12 h. One week after immobilization, a biofilm-like layer of cells had formed on the surface of the silica gel. This resulted in shorter response times and more intensive bioluminescence maxima that appeared as rapidly as 2 h after toluene induction. Considerable second bioluminescence maxima were observed after inductions with 26.5 mg toluene/L. The second and third week after immobilization the biosensor repetitively and semiquantitatively detected toluene in buffered medium. Due to silica gel dissolution and biofilm detachment, the bioluminescent signal was decreasing 20-32 days after immobilization and completely extinguished after 32 days. The reproducible formation of a surface cell layer on the wider end of the tapered optical fiber can be translated to various whole cell bioluminescent biosensor devices and may serve as a platform for in-situ sensors.
Sensors, 2015
This review summarizes principles and current stage of development of fiber-optic chemical sensor... more This review summarizes principles and current stage of development of fiber-optic chemical sensors (FOCS) and biosensors (FOBS). Fiber optic sensor (FOS) systems use the ability of optical fibers (OF) to guide the light in the spectral range from ultraviolet (UV) (180 nm) up to middle infrared (IR) (10 µm) and modulation of guided light by the parameters of the surrounding environment of the OF core. The introduction of OF in the sensor systems has brought advantages such as measurement in flammable and explosive environments, immunity to electrical noises, miniaturization, geometrical flexibility, measurement of small sample volumes, remote sensing in inaccessible sites or harsh environments and multi-sensing. The review comprises briefly the theory of OF elaborated for sensors, techniques of fabrications and analytical results reached with fiber-optic chemical and biological sensors.
Chemical Papers Slovak Academy of Sciences, 2009
Three tetracationic porphyrins differing in the position of charged nitrogen atoms on the periphe... more Three tetracationic porphyrins differing in the position of charged nitrogen atoms on the peripheral substituents-5,10,15,20-tetrakis(N-methylpyridinium-4-yl)porphyrin (TMPyP4), 5,10,15,20tetrakis(N-methylpyridinium-2-yl)porphyrin (TMPyP2), 5,10,15,20-tetrakis(4-trimethylammoniophenyl)porphyrin (TMAPP), and hydrophobic 5,10,15,20-tetraphenylporphyrin (TPP), were immobilized by adsorption and encapsulation in poly(hydroxymethylsiloxane) (PHOMS). The so prepared porphyrin-PHOMS composites were characterized by porosimetry, scanning electron microscopy, fluorescence and diffuse reflectance UV-VIS spectroscopy. It was found that porphyrins are immobilized in the PHOMS matrix in the free-base monomer form Their irradiation produced singlet oxygen O2(1 ∆g) with the lifetime of 10-30 µs.
Alternative synthesis of poly(hydroxymethylsiloxane) for lipase immobilization and use of the adsorbates as esterification biocatalysts
Journal of Sol Gel Science and Technology, Apr 22, 2006
A medium molar mass poly(hydrogenomethyl- siloxane), Me3Si(O-SiHMe)nOSiMe3, (PHMS), has been used... more A medium molar mass poly(hydrogenomethyl- siloxane), Me3Si(O-SiHMe)nOSiMe3, (PHMS), has been used for preparing poly(hydroxymethylsiloxane) supports (PHOMS) for lipase immobilization. The procedure involved the conversion of PHMS to the corresponding poly(alkoxymethylsiloxanes). Me3Si(OSi(OR) Me/nOSiMe3 (PHMS), their alkaline hydrolysis to form poly(siloxanolates) which were then converted to PHOMS by neutralization. The effect of different catalysts and alcohols (methanol, ethanol, 2-propanol) on the course
Lipase Immobilized by Sol-Gel Technique in Layers
Collect Czech Chem Commun, 1995
Commercial lipase was immobilized into an organic-inorganic matrix formed by hydrolysis of silico... more Commercial lipase was immobilized into an organic-inorganic matrix formed by hydrolysis of silicon alkoxides (tetraethoxysilane, dimethyldiethoxysilane and methyltriethoxysilane) with (3-aminopropyl)triethoxysilane, (3-thiopropyl)trimethoxysilane and chlorodiisopropyloctylsilane. Hydrolytic activity of lipase was tested after addition of the enzyme to a prepolymer solution, after gelation, in xerogel particles and in thin layers deposited on glass slides by dip- or spin-coating. The prepolymer containing NH groups showed the higher activity then the native enzyme.
terc-BUTYLMETHYLETHER A JEHO DEGRADACE OXIDACNIMI PROCESY
Chemicke Listy, 2007
... Tabulka I Rychlostní konstanty reakce MTBE a oxidačních mezipro-duktů s O3 a OH Sloučeninaa ... more ... Tabulka I Rychlostní konstanty reakce MTBE a oxidačních mezipro-duktů s O3 a OH Sloučeninaa k(O3) [l mol -1 s-1] k(OH) [109 l mol-1s-1] MTBE 0,14 1,9 TBF 0,78 0,7 MMP 5 3 MA 0,09 - HiBa 5 3 ... O2 + 2 e-+ 2 Haq + → H2O2 (20) 2 H2O + 2 h+ → H2O2 + 2 Haq + (21) ...
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Papers by Gabriela Kuncova