Conjugated polyelectrolytes-initiated chemiluminescence: a biosensing platform for label-free and homogeneous DNA detection.

In this study, it was found that conjugated polyelectrolytes (CPEs) would initiate the strong chemiluminescence (CL) emission of luminol-H2O2 in weak basic media. Using CL spectra, ultraviolet visible light spectra, fluorescence spectra and electron spin resonance (ESR) spectra, the catalytic mechanism of CPEs on luminol-H2O2 CL was discussed in detail. Furthermore, it was found that the catalytic activity of poly [3-(3'-N,N,N-triethylamino-1'-propyloxy)-4-methyl-2,5-thiophene hydro chloride] (PMNT) (a kind of cationic CPEs) on the luminol-H2O2 CL system was closely relevant to the conformation of PMNT. The CL intensity of luminol-H2O2-PMNT system in the presence of single-stranded DNA was much larger than that in the presence of double-stranded DNA. By taking advantage of this phenomenon, a label-free and homogeneous CL detection of DNA hybridization is proposed. The detection limit of target DNA (3σ) was estimated to be as low as 3.7×10(-13)M. The present CL method for DNA hybridization detection offers the advantages of being simple, cheap, rapid and sensitive.