Sensitive colorimetric detection of K(I) using catalytically active gold nanoparticles triggered signal amplification

摘要

In this work, we report a simple, ultrasensitive, and feasible colorimetric assay for metal ion (K+, used as a model) via inherent peroxidase-like enzymatic amplification strategy of gold nanoparticles (AuNPs). It is shown that peroxidase-like activity of AuNPs can be improved dramatically by its surface activation with target-specific aptamer molecules. Whereas when the target exists, the aptamers leave the surface of AuNPs in a target concentration-dependent manner, resulting in a decrease of the nanoenzymatic catalytic ability of AuNPs. Thus, K+ can be quantified in the presence of AuNPs by using a colorimetric sensing probe (3,3',5,5'-tetramethylbenzidine). The color change of the solution is relevant to the dose of the target, and this can be achieved with the naked eyes and monitored by UV-vis spectrometry. A linear dependence between the absorbance and target K+ concentration is obtained under optimal conditions in the range from 0.1 nM to 1 mu M with a detection limit (LOD) of 0.06 nM estimated at the 3S(blank) level. The sensitivity displays to be 2-9 orders of magnitude better than those of other K+ detection methods. This sensing strategy may in principle be universally applicable for the detection of a range of environmental or biomedical molecules of interest. (C) 2016 Elsevier B.V. All rights reserved.