Electrochemiluminescence sensor using gold-nanoparticle modification combining mercaptoacetic acid-assembly

In this paper, an electrochemiluminescence (ECL) sensor is fabricated using a covalent bond immobilization approach. A glassy carbon electrode (GCE) modified with gold nanoparticles (AuNPs@GCE) was prepared using a wet chemical method which acts as a support for the ECL reagent. A monolayer of mercaptoacetic acid (MA) was then assembled onto the AuNPs@GCE surface. Finally, an ECL reagent, bis(2,2′-bipyridyl) (5-amno-1,10-phen) dichlororuthenium [Ru(bpy)2(phen-NH2)]22+, was attached onto the AuNPs@GCE by condensation of the amino group and carboxylic group of MA. Because [Ru(bpy)2(phen-NH2)]22+ is covalently immobilized on the electrode surface without any polymaterials and directly contacts to the electrolyte, in contrast to traditional ECL sensors fabricated using a polymer technique, mass transportation and electron transfer hindrance is negligible and ECL stability is increased obviously. The sensor is applied in cathodic ECL analysis and presents good performance in a linear range from 1.0 × 10−6 mol L−1 to 0.1 mol L−1 and a detection limit of 5 × 10−7 mol L−1 for potassium persulfate.