Tetrakis (4-carboxyphenyl) porphyrin and Ru(bpy)32+ modified SiO2 nanospheres for potential and wavelength resolved electrochemiluminescence

Abstract

Potential resolved electrochemiluminescence (ECL) nanoluminophores are very important for precise analysis and simultaneous determination of multiple targets. Designing ideal potential resolved ECL nanoluminophores, generating multiple high efficiency ECL emissions without overlap and interference of potential and wavelength, is a challenging subject. Herein, we developed a new nanoluminophore, meso-tetra (4-carboxyphenyl) porphine (TCPP)-functionalized chitosan/Ru(bpy)₃²⁺/SiO₂ (CRuSiO₂) (TCPP@CRuSiO₂), with cathode and anode ECL emissions by modifying TCPP on the surface of CRuSiO₂ nanoluminophores. The TCPP@CRuSiO₂ nanoluminophores presented a uniform sphere morphology (∼50 nm). They exhibited two ECL emissions of 695 nm and 610 nm at −1.20 V and 1.15 V, respectively, by using K₂S₂O₈ and tripropylamine (TPrA) as coreactants. Subsequently, the relevant ECL mechanisms are proposed. In the negative potential range, sulfate radicals (SO₄˙⁻) reacted with TCPP⁻, generated by the electro-reduction of S₂O₄²⁻ and TCPP, to form the excited state TCPP*, resulting in ECL-1. In the positive potential range, Ru(bpy)₃³⁺ and TPrA˙, obtained by electro-oxidation of Ru(bpy)₃²⁺ and TPrA, reacted with each other to produce the excited state Ru(bpy)₃²⁺*, leading to ECL-2. The synthesized TCPP@CRuSiO₂ possesses not only potential and wavelength resolved ECL emissions, but also the advantages of easy synthesis, high ECL efficiency, good stability, and easy film formation on the electrode surface. This work enriches ECL nanoluminophores, which are of important application potential in precise analysis and multiplex analysis.