A facile label-free electrochemiluminescence biosensor for target protein specific recognition based on the controlled-release delivery system

This paper described a novel label-free electrochemiluminescence assay for target protein based on a controlled delivery system. Iron oxide magnetic mesoporous silica nanocontainers were prepared by using a general procedure. The prepared magnetic mesoporous silica nanocontainers were applied to load the guest molecules [Ru(bpy)3]2+. Aptamers were used as gatekeepers on the pore outlets of the nanocontainers. In the presence of target proteins, the specific aptamer–protein interactions were employed as triggers for uncapping the pores and releasing the guest molecules from the nanocontainers. The amount of the guest molecule [Ru(bpy)3]2+ released from the magnetic mesoporous silica nanocontainers was monitored by the electrochemiluminescence assay. The results show that the releasing amount of [Ru(bpy)3]2+ is proportional to the thrombin concentration in the range of 0.6 pM–0.8 nM with a detection limit of 0.5 pM (S/N=3). The present work demonstrates that the fabricated nanocontainer using aptamer as the cap is a highly sensitive and selective key-in lock gating system for the label-free ECL biosensor.