ABSTRACT
As an important inorganic element, iodine not only plays an important role in human growth and metabolism, but also has an irreplaceable role in the chemical engineering, medicine, food and other fields.Thus the detection of iodine ion is of important significance.In this work, colorimetric recognition and sensing of iodine ion with high sensitivity was proposed based on target induced shielding of the peroxidase-like activity of bare platinum nanoparticles ( PtNPs ).This assay exhibited simplicity and cost-effectiveness.The recognition of iodine ion by bare PtNPs could be fulfilled in a few seconds and the assay could be accomplished within 10 min.The detection range for iodine ion was 20 nmol/L-5.0 μmol/L and the detection limit was 8 nmol/L ( S/N = 3 ).Furthermore, the new assay system did not require surface modification of nanoparticles, nor complex organic synthesis.This assay was successfully applied to detection of iodine concentration in real salt and water samples, exhibiting promising application prospects.
ABSTRACT
An enzyme cascade strategy was introduced for sensitive detection of acid phosphatase ( ACP) . Pyrophosphate ions ( PPi ) can strongly bound Fe3+and thus hinders the production of Prussian blue nanoparticles (PBNPs). ACP can hydrolyze PPi to form phosphate ions, and the released Fe3+reacts with potassium ferrocyanide ( K4[ Fe ( CN )6] ) to form PBNPs. The formed PBNPs have high peroxidase-like activity, which can decompose hydrogen peroxide ( H2O2) to produce hydroxyl radical (·OH) for oxidizing the typical substrate of 3,3′,5,5′-tetramethylbenzidine ( TMB). Therefore, a novel sensing strategy for detecting ACP based on the high signal amplification of enzyme cascade was constructed. The results showed that there was a good linear relationship between the absorbance of oxidized TMB ( oxTMB ) and the concentration of ACP in the range of 3-20 U/L, with a detection limit of 0. 8 U/L. Different from the conventional enzyme cascades in which the product of one enzyme is the substrate of the other, this study opens up a new way to construct novel enzyme cascade system.