Aptamer-based rolling circle amplification coupled with graphene oxide-based fluorescence resonance energy transfer for sensitive detection of cardiac troponin i

Combining the high affinity and specificity of an aptamer for a protein, a highly sensitive strategy for protein detection was developed based on rolling circle amplification (RCA) and graphene oxide based fluorescence resonance energy transfer (FRET). In this strategy, a protein was captured using an antibody-coated microplate, and then a circularized product containing an aptamer-primer and padlock probe was added to form a sandwich structure. Under the influence of DNA polymerase, the RCA reaction extended the primer sequence, and generated hundreds of copies of the circular DNA template. Detection of the RCA products via FRET using graphene oxide allowed the sensitivity enhancement in target protein detection. This method was used to detect the target protein of cardiac troponin I (cTnI) with a detection limit as low as 14.40 pg mL^-1. The highly sensitive and specific assay can be used as a promising tool in clinical sample analysis.