RESUMO
A series of aliphatic tertiary amines (HEPES, POPSO, EPPS and BIS-TRIS) commonly used to buffer the pH in biological experiments, were examined as alternative, non-toxic co-reactants for the electrogenerated chemiluminescence (ECL) of tris(2,2'-bipyridine)ruthenium(ii) ([Ru(bpy)3](2+)). These were found to be very attractive as "multi-tasking" reagents, serving not only as co-reactants, but also fulfiling the roles of pH buffer and supporting electrolyte within an aqueous environment; thus significantly simplifying the overall ECL analysis. Sub-nanomolar detection limits were obtained for [Ru(bpy)3](2+) in the presence of BIS-TRIS, making this species an valuable option for co-reactant ECL-based bioanalytical applications.
Assuntos
Eletroquímica/métodos , Eletrólitos/química , Luminescência , Rutênio/química , 2,2'-Dipiridil/química , Aminas , Soluções Tampão , Técnicas de Química Analítica , Eletrodos , HEPES/química , Concentração de Íons de Hidrogênio , Indicadores e Reagentes , Medições Luminescentes , Modelos Químicos , Fosfatidilserinas/química , Piperazinas/química , Solubilidade , Ácidos Sulfônicos/química , Trometamina/análogos & derivados , Trometamina/químicaRESUMO
We demonstrate a new approach to manipulate the selective emission in mixed electrogenerated chemiluminescence (ECL) systems, where subtle changes in co-reactant properties are exploited to control the relative electron-transfer processes of excitation and quenching. Two closely related tertiary-amine co-reactants, tri-n-propylamine and N,N-diisopropylethylamine, generate remarkably different emission profiles: one provides distinct green and red ECL from [Ir(ppy)3] (ppy=2-phenylpyridinato-C2,N) and a [Ru(bpy)3](2+) (bpy=2,2'-bipyridine) derivative at different applied potentials, whereas the other generates both emissions simultaneously across a wide potential range. These phenomena can be rationalized through the relative exergonicities of electron-transfer quenching of the excited states, in conjunction with the change in concentration of the quenchers over the applied potential range.