RESUMEN
G-quadruplex-forming sequence can be formed through a copper(I) ion (Cu(+))-catalyzed click chemistry between azide- and alkyne-modified short G-rich sequences in aqueous solution, eliminating immobilization and washing steps of conventional assays. The source for Cu(+) was generated from the reduction of Cu(2+) with the reductant of sodium ascorbate. In the presence of hemin and K(+), the self-assembly of hemin/G-quadruplex structure has the activity of horseradish peroxidase (HRP), which can catalyze its colorless substrate tetrazmethyl benzidine (TMB) into a colored product. Hence, the concentration of Cu(2+) can be evaluated visually for qualitative analysis according to the color change of the solution, and the optical density (OD) value of the resulting solution at 450 nm was also recorded using a microplate reader for quantitative analysis.
Asunto(s)
Técnicas Biosensibles/métodos , Cobre/análisis , Cobre/sangre , ADN Catalítico/química , Agua Potable/análisis , Hemina/química , Alquinos/química , Azidas/química , Secuencia de Bases , Cationes Bivalentes/análisis , Cationes Bivalentes/sangre , Química Clic , Colorimetría/métodos , G-Cuádruplex , Peroxidasa de Rábano Silvestre/química , Humanos , Límite de DetecciónRESUMEN
An enzyme-free and label-free fluorescence turn on biosensor for amplified copper(II) ion (Cu(2+)) detection has been constructed based on self-assembled DNA concatamers and Sybr Green I. This assay is simple, inexpensive and sensitive, enabling quantitative detection of as low as 12.8 pM Cu(2+).
Asunto(s)
Técnicas Biosensibles/métodos , Cobre/análisis , ADN/química , Colorantes Fluorescentes/química , Compuestos Orgánicos/química , Secuencia de Bases , Benzotiazoles , Cobre/química , ADN/genética , Diaminas , Quinolinas , Espectrometría de FluorescenciaRESUMEN
The biological and non-biological factors affecting soil N availability in grassland ecosystems were reviewed in this paper. Nitrogen cycling in grassland ecosystems is one of the focuses widely concerned. Nitrogen mineralization is affected by many factors in grassland ecosystem, which can be classified into biological and non-biological ones. Biological factors include soil animals, soil microorganisms and plants. Soil animals could accelerate the organic matter to degrade. The species, structure and function of soil microorganisms correlate significantly with N degradation and mineralization. Different vegetation has different effects on soil nitrogen mineralization. The non-biological factors include environmental factors and anthropogenic disturbance, which have direct and obvious effects on N mineralization. The effects of soil temperature and moisture on N mineralization are given more attention, but many phenomena, such as the effects of soil type, soil structure and vegetation type on N mineralization still could not be explained clearly, and no general agreements were reached. Anthropogenic disturbance such as grazing, firing and fertilization influence N mineralization evidently. It is of great significance to understand the N cycling pattern and N availability in different grassland ecosystems all around the world.