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 8.3fM, 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. Copyright (c) 2010 Elsevier B.V. All rights reserved.