A solid-state electrochemiluminescence sensing platform for detection of adenosine based on ferrocene-labeled structure-switching signaling aptamer

A solid-state electrochemiluminescence sensing platform based on ferrocene-labeled structure-switching signaling aptamer (Fc-aptamer) for highly sensitive detection of small molecules is developed successfully using adenosine as a model analyte. Such special sensing platform included two main parts, an electrochemiluminescence (ECL) substrate and an ECL intensity switch. The ECL substrate was made by modifying the complex of Au nanoparticle and Ruthenium (II) tris-(bipyridine) (Ru(bpy)₃²⁺-AuNPs) onto Au electrode. An anti-adenosine aptamer labeled by ferrocene acted as the ECL intensity switch. A short complementary ssDNA for the aptamer was applied to hybridizing with the aptamer, yielding a double-stranded complex of the aptamer and the ssDNA on the electrode surface. The introduction of adenosine triggered structure switching of the aptamer. As a result, the ssDNA was forced to dissociate from the sensing platform. Such structural change of the aptamer resulted in an obvious ECL intensity decrease due to the increased quenching effect of Fc to the ECL substrate. The analytic results were sensitive and specific.