Ultrasensitive aptamer-based protein detection via a dual amplified biocatalytic strategy

We present an ultrasensitive aptasensor for the electronic monitoring of proteins through a dual amplified strategy in this paper. The target protein thrombin is sandwiched between an electrode surface confined aptamer and an aptamer–enzyme–carbon nanotube bioconjugate. The analytical signal amplification is achieved by coupling the signal amplification nature of multiple enzymes with the biocatalytic signal enhancement of redox-recycling. Our novel dramatic signal amplification strategy, with a detection limit of 8.3 fM, shows about 4 orders of magnitude improvement in the sensitivity for thrombin detection compared to other universal single enzyme-based assay. This makes our approach an attractive alternative to other common PCR-based signal amplification in ultralow level of protein detection.