论文部分内容阅读
One solid-state electrochemiluminescence(ECL) protein biosensor based on the competing reaction and substitute reaction between protein-to-DNA aptamer and DNA-to-DNA aptamer was proposed.Additionally,the biosensor was based on ECL photo-quenching effect of ferrocene(Fc) to tris(2,2’-bipyridyl)ruthenium(II)(Ru(bpy)32+).It was built up by modification of Au nanoparticles(AuNPs) and Ru(bpy)3 2+ on one Au electrode firstly,and then self-assembly of one special double-stranded DNA(dsDNA) onto the electrode.This dsDNA was prepared by hybridization of one Fc labeled molecular beacon single-stranded DNA(ssDNA) and one anti-thrombin aptamer ssDNA.Without the target protein,this Fc-dsDNA/Ru(bpy)3 2+-AuNPs/Au electrode trigged strong ECL signal,so we called it ECL “signal on” state.When thrombin was present in the sensing solution,the protein reacted with its aptamer from the Fc-dsDNA/Ru(bpy)3 2+-AuNPs/Au electrode.Then the left molecular beacon ssDNA on the electrode recovered to its normal stem-loop structure and consequently its Fc labeler was close enough to the electrode surface to quench the ECL signal from Ru(bpy)3 2+.It was in ECL “signal off” state.We measured the decrease in ECL intensity to sense the target protein.This was one endeavour to sense protein by using un-labeling target or probe strategy,which gave higher sensitivity and selectivity due to the better combination efficiency of protein and the un-labeled aptamer.6.25 fmol/L thrombin was detected out.