Functionalized magnetic nanoparticle with poly(3-thiopheneacetic acid) and its application for electrogenerated chemiluminescence sensor

Polymer-coated magnetic nanoparticles (MNPs) have been prepared and used as an immobilization matrix for the fabrication of solid-state tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)32+) electrogenerated chemiluminescence (ECL) sensor. The pre-synthesized maghemite (γ-Fe2O3) MNPs were coated with poly(3-thiopheneacetic acid) based on an oxidative polymerization method using KMnO4. The poly(3-thiopheneacetic acid)-coated MNPs have formed the clusters with average diameter of 200–500 nm. The multilayer films of poly(3-thiopheneacetic acid)-coated MNPs were uniformly formed on the surface of a Pt electrode by an external magnet. The Ru(bpy)32+ was rapidly incorporated into the multilayer films within 5 min through the electrostatic interaction between the Ru(bpy)32+ and the negatively charged carboxylates of 3-thiopheneacetic acid at pH 7.0. Due to the fast mass transport in the multilayer films of the functionalized MNPs, the present Ru(bpy)32+ ECL sensor based on the functionalized MNPs showed improved ECL sensitivity for tripropylamine (TPA) compared to the Nafion-based ECL sensor. The present ECL sensor exhibited a quite low limit of detection for TPA (49 nM). The sensor-to-sensor reproducibility was very good (R.S.D. = 5%).