Effects of Label-free Fluorescence Aptasensors with Different Aptamer Length on Quenching of Carbon Dots

Abstract Label-free fluorescence aptasensors have the advantages of better detection sensitivity, simple manufacturing process and no pollution. In this experiment, the effect of aptamer base number on the performance fluorescence aptasensors has been studied. Thrombin of 15 base number, ATP of 27 base number and DA of 58 base number were selected, and then constructed three kinds of fluorescent probes about Au/Aptamer/CQDs nanostructures with gold nanoparticles and carbon dots. By studying the quenching degree of carbon dots with each probe, the quenching degree of carbon dots fluorescence by ATP probe was the highest, thrombin probe was the worst, and the DA probe was between ATP probe and DA probe. This indicates that with the increase of the aptamer base number in the probe, the more carbon dots are adsorbed on the aptamer and the more fluorescence quenching occurs, but the aptamer will be winding when it has too many bases, leading to the quenching unstable of carbon dots fluorescence. This study provides a useful reference for the construction and detection of fluorescent aptasensors, and has a great potential in the field of small molecule detection.