Ultrasensitive self-enhanced electrochemiluminescence sensor based on novel PAN@Ru@PEI@Nafion nanofiber mat

Abstract

In the present work, a novel self-enhanced electrochemiluminescence (ECL) composite was for the first time prepared by simply electrospinning a mixture of polyacrylonitrile (PAN), Ru(bpy)₃²⁺, poly(ethylenimine) (PEI) and Nafion, and defined as PAN@Ru@PEI@Nafion nanofiber mat (PAN@Ru@PEI@Nafion_nfm). Herein, Ru(bpy)₃²⁺ was applied as an ECL reagent, and PEI was selected as a co-reactant due to the abundant tertiary amine groups in its backbone. In order to further improve the ECL efficiency of the Ru(bpy)₃²⁺–PEI system, we innovatively loaded Ru(bpy)₃²⁺ and PEI into PAN nanofibers simultaneously by a one-step electrospinning technique. As a result, the electronic transmission distance between them was sharply shortened. Meanwhile, with the help of electrostatic interaction between positively charged Ru(bpy)₃²⁺ or PEI and negatively charged Nafion, exfoliation of Ru(bpy)₃²⁺ and PEI from the PAN nanofiber mat was effectively avoided. As expected, the luminous nanofibers exhibited excellent ECL performance including high efficiency and good stability. On this basis, we fabricated a new self-enhanced ECL sensor with excellent analysis performance. Using α-naphthol as an analytical probe, the sensor showed a wide linear range from 1.0 × 10⁻¹² to 1.0 × 10⁻⁷ M with a low detection limit of 1.0 × 10⁻¹² M. When it was applied to detect α-naphthol from carbaryl hydrolysis, the results were well consistent with those obtained from the high efficiency liquid chromatography-diode array detector (HPLC-DAD) method, indicating the potential application of the ECL sensor in real sample assays.