Sensitive and selective detection of digoxin based on fluorescence quenching and colorimetric aptasensors

Abstract

Digoxin is a cardiac glycoside with a narrow therapeutic index that is commonly used to treat heart failure. In this study, we designed selective, sensitive and fast fluorescence quenching and colorimetric aptasensors for the detection of digoxin based on aqueous gold nanoparticle (AuNP) suspension. In the absence of digoxin, aptamers are adsorbed on the surface of AuNPs. Therefore the well-dispersed AuNPs remain stable against salt-induced aggregation and the fluorescence of the ATTO 647N-aptamer is efficiently quenched by AuNPs. In the presence of digoxin, aptamers bind to digoxin, leading to the aggregation of AuNPs by salt, resulting in a color change from red to blue and recovery of the fluorescence emission. Fluorescence quenching and colorimetric aptasensors showed high selectivity toward digoxin with a limit of detection (LOD) as low as 392 and 571 pM, respectively. Our designed aptasensors were successfully used to detect digoxin in serum.