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An electrochemical biosensor for the detection of genetically modified food components is presented. The biosensor was based on 21-mer single-stranded oligonucleotide (ssDNA probe) specific to either 35S promoter or nos terminator, which are frequently present in transgenic DNA cassettes. ssDNA probe was covalently attached by 5′-phosphate end to amino group of cysteamine self-assembled monolayer (SAM) on gold electrode surface with the use of activating reagents – water soluble 1-ethyl-3(3′-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxy-sulfosuccinimide (NHS). The hybridization reaction on the electrode surface was detected via methylene blue (MB) presenting higher affinity to ssDNA probe than to DNA duplex. The electrode modification procedure was optimized using 19-mer oligoG and oligoC nucleotides. The biosensor enabled distinction between DNA samples isolated from soybean RoundupReady® (RR soybean) and non-genetically modified soybean. The frequent introduction of investigated DNA sequences in other genetically modified organisms (GMOs) give a broad perspectives for analytical application of the biosensor.

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Cornelian cherry (Cornus mas L.), a fruit found in Central Europe, is used as a traditional ingredient in fruit preserves. In this study, we analyzed seven cultivars of Cornelian cherry growing in Poland and the differences between them in sugar content, total polyphenol content, and total chlorophyll content. Moreover, we measured the antioxidant potential of Cornelian cherry extracts was also measured. Polyphenols were found to be highest in Słowianin, Wydubieckij and Jolico cultivars. The presented research outcomes were extremely different from the results obtained for the other cultivars of Cornelian cherry. The electrochemical analysis of extracts proved that compounds contained in Cornelian cherry had the reducing against peroxyl radicals, which makes these extracts an important class of nutritional antioxidants. Our study showed that electrochemical assessment can replace the standard colorimetric tests in the evaluation of the antioxidant potential of analyzed compounds. Aplicación para el cribado electroquímico novedoso del potencial antioxidante y fitoquímicos en extractos de Cornus mas RESUMEN La cereza de cornalina (Cornus mas L.), una fruta que se encuentra en Europa Central, se usa como ingrediente tradicional para la elaboración de conservas de frutas. El presente estudio analizó siete cultivares de cerezas Cornus mas que crecen en Polonia, así como las diferencias en el contenido de azúcar, el contenido total de polifenoles y el contenido total de clorofila existentes entre ellas. Además, se midió el potencial antioxidante de los extractos de esta cereza. Se constató que los polifenoles son más abundantes en los cultivares de Słowianin, Wydubieckij y Jolico. Los resultados de esta investigación mostraron la existencia de diferencias muy importantes al compararlos con los resultados obtenidos para los otros cultivares de la cereza de Cornus mas. El análisis electroquímico de los extractos mostró que los compuestos contenidos en dicha cereza disminuyen los radicales peroxilo, lo que hace de estos extractos una clase importante de antioxidantes nutricionales. El estudio reveló que la evaluación electroquímica puede remplazar las pruebas colorimétricas estándar en la evaluación del potencial antioxidante de los compuestos analizados.