Ultrasensitive electrochemiluminescence biosensor for detection of laminin based on DNA dendrimer-carried luminophore and DNA nanomachine-mediated target recycling amplification

Herein, a novel electrochemiluminescence (ECL) biosensor was proposed for ultrasensitive detection of laminin (LN), in which DNA dendrimer (D) as a promising nanocarrier for luminophore and DNA nanomachine as tactic for target recycling. The DNA dendrimer was synthesized by hybridization between sense and its antisense Y-shaped DNAs which were formed via reaction between single-stranded DNA (ssDNA) with a thiol group at the 5'-end and a synthesized trimeric cross-linker of tris(2-maleimidoethyl)amine. This dendrimer provided abundant double-stranded DNA (dsDNA) to achieve high loading efficiency for ECL luminophore. Simultaneously, N-(aminobutyl)-N-(ethylisoluminol) (ABEI) was conjugated with doxorubicin (Dox, a intercalator of dsDNA) to form the ECL indicator (Dox-ABEI) which could effectively intercalate DNA dendrimer to form the ECL probe (D-Dox-ABEI). Subsequently, a DNA nanomachine activated by target protein was involved to obtain numerous output ssDNA (S2) which was amplified by exonuclease III-assisted recycle and immobilized on ssDNA (S1)-modified sensing electrode surface via complementation. Thereby, abundant D-Dox-ABEI probes were captured by S2 to construct the biosensor for target protein detection. The proposed ECL biosensor realized the ultrasensitive detection of LN with a linear range from 0.1pg/mL to 100ng/mL and a low detection limit of 0.0661pg/mL. Impressively, the application of this ECL biosensor would provide the great potential for analysis of other proteins, revealing a new avenue for early diagnosis and the prognosis evaluation of various diseases.