An enzyme biosensor specific for formaldehyde has been developed using pH-sensitive field effect transistors (FET) as a transducer and alcohol oxidase (AOX) from Hansenula polymorpha as a sensitive ...element. The steady-state response time of the developed biosensor was 10-60 s. The linear dynamic range (in semi-logarithmic scale) of the sensor output signal corresponded to 10-300 mmol dm super(-3) formaldehyde concentration. The operational stability of the biosensor was not less than 7 h and the relative standard deviation approximately 1-3%. When stored at +4 degree C, the response was stable for more than 30 days. The biosensor demonstrated high specificity to formaldehyde with no potentiometric response to primary alcohols. The influence of buffer concentration and enzyme concentration in the biomembrane on the sensor signal was investigated. The specific biosensor could also be successfully used for highly selective, quantitative estimation of mercury ion in an aqueous solution.
An important but underrepresented element in the growing body of work on informal science education is research designed to examine the nature and scope of children's activities related to science, ...nature, and technology by developing structured interviews for parents of middle class preschool and kindergarten children and for students in upper-elementary grades. These interviews can be used to construct profiles of children's exposure to science activities outside of school, such as watching television, reading, attending exhibits or events at community facilities, participating in experiments or demonstrations at home, and asking questions of parents. We describe how these interviews were developed, what kinds of information this type of research enabled us to obtain, and what lessons we have learned in the process. The level of extracurricular participation reported in a wide range of science-related activities was very high. Structured interviews can help teachers gain information about students' exposure to science-related learning activities in their home and community. This information can be used as a platform on which classroom instruction can be built (Autorenreferat übernommen. Copyright John Wiley & Sons, Inc.).
This paper reports the application of functionalized platinum (Pt) electrodes and ChemFETs sensors for metal ion detection. The sensitive part of the sensors consists in a film of ethyl ...2-thienylglyoxalate (ETGO) deposited by a spin-coating process. Electrochemical impedance spectroscopy was used to investigate the electrical properties of functionalized Pt electrodes. The optimized working conditions of the sensors have been studied with regard to the sensitivity performances, in particular, the polarization was adjusted to −
0.85 V/ESC in order to neglect the Warburg effects at low frequencies. The functionalized Pt electrodes have shown a good sensitivity towards Cu(II) ions, whereas low response towards Ca(II) ions was observed. The ETGO/ISFET devices have shown good sensitivity (14 mV/decade) and linear responses over at least two decades of Cu(II) activity compared to (0.5 mV/decade) for Ca(II) ions.
The photometric method is suggested for ethanol analysis by means of purified alcohol oxidase isolated from a wild strain of methylotrophic yeast Hansenula polymorpha. Three different chromogenic ...systems for peroxidative oxidation together with alcohol oxidase reaction have been used. For the first time the intact cells of the catalase-negative mutant as a source of alcohol oxidase are employed in the photometric alcohol assay. The prospects for application of the latter method for practical purposes are discussed.
Cellular sensors for methanol and ethanol determination were developed using immobilized mutant cells of methylotrophic yeasts Hansenula polymorpha and Pichia pinus (able to extrude protons in the ...presence of alcohol) and pH-sensitive field effect transistors (pH-SFETs). The intact cells of yeasts were immobilized in Ca-alginate gel to obtain a biomembrane. The minimal detectable response was obtained to approximately 0.5 mM of methanol and ethanol, a linear dependence of biosensor's response on the logarithmic alcohol concentration was observed in the range from 5 to 100 mM for both types of alcohol. The prospects for application of biosensors to determine alcohols in the analytical practice are discussed.
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