Abstract: The possibility of using disposable plastic-carbon potentiometric sensors as enzyme biosensors was examined. Urease enzyme was immobilized on poly(vinyl chloride) based H+- or NH4+-selective membranes using cellulose acetate. This approach has resulted in a potentiometric response on changing the pH of the solution or NH4+ ion content due to an enzymatic reaction that occurs between urease and urea. Both types of potentiometric biosensors for urea were characterized by good analytical parameters as high sensitivity and fast response time.
Abstract: Application of conducting polymers with additional functional groups for a solid contact formation and photocurable membranes as sensitive elements of solid-state chemical sensors is discussed. Problems associated with application of UV-curable polymers for sensors are analyzed. A method of sensor fabrication using copolymerized conductive layer and sensitive membrane is presented and the proof of concept is confirmed by two examples of solid-contact electrodes for Ca ions and pH.
Abstract: A solid state electrochemiluminescence (ECL) sensor based on Ru(bpy)32+-encapsulated silica nanoparticles (RuNP) covalently immobilised on a screen printed carbon electrode has been developed and characterised. RuNPs were synthesised using water-in-oil microemulsion method, amino groups were introduced on their surface, and they were characterised by transmission electron microscopy. Aminated RuNPs were covalently immobilised on activate screen-printed carbon electrodes to form a solid state ECL biosensor. The biosensor surfaces were characterised using electrochemistry and scanning electron microscopy, which showed that aminated nanoparticles formed dense 3D layers on the electrode surface thus allowing immobilisation of high amount of Ru(bpy)32+. The developed sensor was used for ECL detection of biogenic polyamines, namely spermine, spermidine, cadaverine and putrescine. The sensor exhibited high sensitivity and stability.
Abstract: An alcohol dehydrogenase-based biosensor was prepared and tested for its use to determine ethanol in beer. The biosensor is based on a screen-printed carbon electrode (SPCE) modified by rhodium dioxide and immobilized with a biocatalytic layer containing the enzyme. Function of the enzyme biosensor was tested in model ethanol samples, in which it showed a linear range of 15–120 g∙L−1 with a detection limit of 3.3 g∙L−1 (established as 3σ) and response time of 19 s. In a potential window from –0.2 to +0.45 V, interferences of both ascorbic and uric acids were negligible. Several types of marketed beers of Czech provenance were selected and subjected to measurements under optimized conditions but without any pretreatment of real samples. When compared with the reference method (gas chromatography), the results were in quite good agreement for beers of the pale lager type but higher contents of ethanol were indicated in the samples of dark lager beers.
Abstract: Novel pyrolyzed photoresist carbon electrodes for electroanalytical applications have been produced by photolithographic technology followed by pyrolysis of the photoresist. A study of the determination of Ni(II) dimethylglyoximate (Ni-DMG) through adsorptive cathodic stripping voltammetry at an in situ bismuth-modified pyrolyzed photoresist electrode (Bi-PPCE) is reported. The experimental conditions for the deposition of a bismuth film on the PPCE were optimized. The Bi-PPCE allowed the analysis of trace concentrations of Ni(II), even in the presence of Co(II), which is the main interference in this analysis, with cathodic stripping square wave voltammograms characterized by well-separated stripping peaks. The calculated limits of detection (LOD) were 20 ng∙L−1 for Ni(II) alone and 500 ng∙L−1 in the presence of Co(II). The optimized method was finally applied to the analysis of certified spring water (NIST1640a).
Abstract: Electrodes based on arrays of TiO2 nanowires were prepared by template sol-gel synthesis with the goal of developing a hydrazine photoelectrochemical sensor. Experimental conditions were chosen so that the gelation reaction occurred inside the nanopores of track-etched polycarbonate membranes, with consequent filling with TiO2 nanowires. Different procedures for the removal of the template were examined, in order to obtain arrays of self-standing TiO2 nanowires. The nanowire arrays were bound to fluorine doped tin oxide substrates to produce handy photoelectrodes. The photocurrent recorded with the photoelectrodes in the presence of hydrazine showed significant dependence on the pollutant concentration. The development of a photoelectrochemical sensor for hydrazine detection in water samples, based on this principle, is presented.