Colorimetric theophylline aggregation assay using an RNA aptamer and non-crosslinking gold nanoparticles

摘要

The authors are presenting a rapid method for the determination of theophylline using unique non-crosslinking gold nanoparticle (AuNP) aggregation. An RNA aptamer against theophylline is firstly split into two RNA fragments which then interact with bare AuNPs. The two RNA probes cause an enhancement of the salt tolerance of AuNPs. However, in the presence of theophylline, the RNA probes form a complex with theophylline so that less RNA probes are available to protect the AuNPs from salt-induced aggregation. Theophylline induced aggregation of AuNPs is accompanied by a color change from red to blue. The color change can be detected visually and via UV-vis absorptiometry by ratioing the absorbances at 650 and 520 nm. The ratio increases linearly in the 0.1 to 20 mu Mtheophylline concentration range, with a 67 nM limit of detection. The method is highly sensitive and selective.