Dual-mode detection of PARP-1 by fluorescence and chemiluminescence

Poly(ADP-ribose) polymerase-1 (PARP-1) is overexpressed in various cancer cells and has attracted much attention due to the bright prospect of application as a novel target in cancer diagnosis. Detection of PARP-1 activity is significant, however, it is relatively difficult since it lacks superiority property that can be used to detect conveniently. In this work, a dual-mode, label-free strategy for the detection of PARP-1 with gold nanocluster (AuNCs) was developed. Firstly, we modified magnetic beads (MBs) with specific dsDNA (dsDNA-MB). Then PARP-1 catalyzed the synthesis of negatively charged poly(ADP-ribose) (PAR). Because of the strong electrostatic interaction between PAR and positively charged AuNCs, abundant AuNCs were adsorbed on PAR. After the magnetic separation, AuNCs adsorbed on PAR produced strong fluorescence (FL) and catalyzed the luminol-H2O2 system to produce strong chemiluminescence (CL). According to the generated FL and CL signals, PARP-1 has been detected sensitively ranging from 0.01 to 1.0 U, and the limit of detection (LOD) is estimated to be 0.009 U and 0.007 U, respectively. Dual-mode detection is more reliable and convenient than single-mode detection. Moreover, this dual-mode strategy was available to evaluate inhibitors and distinguish cancer cells from normal cells. Thus, this method opened a new avenue for clinical diagnosis and inhibitor research in the future.