A nanoparticle-based thermo-dynamic aptasensor for small molecule detection

Small molecules (MW < 1000 Da) represent a large class of biomarkers of interest. Recently, a new class of biosensors has been emerging thanks to the recognition properties of aptamers, short DNA or RNA single strands, selected against such small molecular targets. Among them, an adenosine-specific aptamer has been largely described and used due to its remarkable affinity to this small target (K-D = 6 mu M). In this paper, we achieved the proof-of-principle of an aptasensor based on the thermodynamic follow-up of adenosine binding with engineered split-aptamer sequences. The detection is carried out by surface plasmon resonance imaging of split-aptamer micro-arrays, while signal amplification is ensured by gold nanoparticles (AuNPs). This original approach based on DNA sequence engineering and AuNP conjugation enabled us to reach limits of detection (LOD) 200 times lower than the KD measured in solution with the native aptamer (LOD = 30 nM).