Detection of PARP-1 activity based on hyperbranched-poly (ADP-ribose) polymers responsive current in artificial nanochannels

The cellular enzyme poly ADP (ADP: adenosine diphosphate)-ribose polymerase-1 (PARP-1) plays key roles in DNA repair. Its activity is closely related to various cancer developments. Detection of PARP-1 activity is significant, however, it is relatively difficult since it lacks superiority property that can be used to detect conveniently. PARP-1 lead to the synthesis of hyperbranched poly (ADP -ribose) polymers (PAR) using nicotinamide adenine dinucleotide (NAD(+)) as substrate during DNA damage repairing. In this paper, we found that hyper-branched PAR increased the steric hindrance and reduced the flux of probe ions effectively in anodic aluminum oxide (AAO) nanochannels. To the best of our knowledge, few papers have been reported that hyper-branched polymer has the similar effects in nanochannels as G-quadntplex DNA. Thus, a novel and simple strategy for PARP-1 detection has been proposed due to its great impacts on the diffusion flux of ferricyanide in AAO. It is also proved that electrostatic repulsion is another important factor to influence the current. The method is label free, simple and sensitive. Quantitative detection of PARP-1 activity was achieved with the detection limit of 0.006 U, which is lower or comparable to the most reported methods. The method has good accuracy and reproducibility. The strategy has been used to detect PARP-1 activity in real breast cancer cells and to evaluate PARP-1 inhibitors with satisfactory results, indicating that it is a potential powerful tool for clinical diagnosis and drug development in the future.