| The gold nanoparticles (AuNPs) colorimetric method has aroused attention because of its many advantages, such as special spectral properties, rapidly, simplicity, and no large-scale instrument. In this paper, we explored the AuNPs-based colorimetric assays for clenbuterol and thrombin.1. Simple and sensitive detection of clenbuterol using gold nanoparticles as colorimetric probesA simple and sensitive method for the detection of clenbuterol was described using AuNPs as the colorimetric probes. Clenbuterol could induce the aggregation of AuNPs, resulting in a color change from red to blue or purple. The concentration of clenbuterol could be determined with the naked eye or the UV-vis spectrometer. Results showed that a linear response toward clenbuterol concentration in the range from2.0×10-9M to1.0×10-6M with the detection limit of0.61nM. This method had such advantages as sensitive, simple, inexpensive and wide linear range, which provided a potentially useful tool for the clenbuterol detection. The mechanism of the aggregation of the AuNPs in this system was discussed.2. Simple and sensitive aptamer-based sensing of thrombin with positive-charged gold nanoparticle as colorimetric probesIn this work, a simple and sensitive aptamer-based colorimetric method for thrombin detection using positive-charged gold nanoparticle probes has been reported. In the absence of thrombin, the negatively-charged thrombin aptamer (TBA) has strong binding ability to the surface of positively-charged AuNPs through electrostatic interaction, which leads to their aggregation and a consequent an obvious color change of positively-charged AuNPs from wine red to blue. In the prescence of thrombin, thrombin would interact with TBA and induce TBA to fold into a G-quadruplex structure, and the G-quadruplex could not induce the aggration of AuNPs. This color change was dependent on the concentration of thrombin, realizing the detection of thrombin in a very convenient way. A linear range from0.5to400nM is obtained for thrombin, which is as low as the most sensitive methods. Significant color change is visible at as low as50nM. This method has such advantages as sensitive, simple, and inexpensive, which provides a potentially useful tool for the thrombin detection. |
