Vernetzte Gleichgewichte: Verhalten von lod gegenüber Petrolether,Wasser und Kaliumiodid

Because of the formation of KI₃, potassium iodide increases the extraction rate of iodine from petroleum ether into water. Nernst's constant of the distribution of iodine in the system water/petroleum ether (KN = 34.1 ± 4.6) and the equilibrium constant of the formation of KI₃ from iodine and potasium (K_K = 820 ± 203 1 · mol⁻¹) are determined by titration of I₂ or KI₃ in the separated organic and aqueous layers with thiosulfate standard solution. Aspects of environmental protection are an integral part of the experiments,e.g. iodine and petroleum ether are recycled.     

Heterogeneous and Homogeneous Aptamer‐Based Electrochemical Sensors for Thrombin

Nanomolar concentrations of thrombin were electrochemically monitored using heterogeneous switch‐on and homogeneous switch‐off approaches that incorporated ferrocenyl aptamers. For the first time, the heterogeneous approach was coupled to a glucose/glucose oxidase (GOx) amplification‐regeneration system which increased its sensitivity by 2 folds with detection limits of 4.3 nM and 2.5 nM in the absence and presence of glucose/GOx, respectively. We also present a new homogeneous system involving the ferrocenyl aptamer binding thrombin in solution causing a significant decrease in its diffusion coefficient. Thus the ferrocene anodic current decreased at an unmodified gold electrode with detection limit of 3.9 nM and 12 times larger linear range than the heterogeneous method.     

G‐Quadruplex‐Based DNAzymes Aptasensor for the Amplified Electrochemical Detection of Thrombin

A novel G‐quadruplex‐based DNAzymes aptasensor for the amplified electrochemical detection of thrombin has been described. The aptasensor utilized a combination of hemin and guanine‐rich thrombin‐binding aptamer (TBA) to form horseradish peroxidase (HRP)‐mimicking DNAzymes with peroxidase catalytic activity. In the presence of thrombin, the enzyme activity could be extensively promoted, thereby providing the amplified electrochemical readout signals for detecting thrombin. This aptasensor exhibited high sensitivity and selectivity for thrombin determination, which enabled the analysis of thrombin with a detection limit of 6×10^–11 M. On the basis of results, this method could have broad applications in the detection of proteins and other biomolecules.