A label-free electrochemical biosensor for sensitive analysis of the PARP-1 activity

[Display omitted] •Positively charged electroactive molecular of methylene blue (MB) was used as probe to recognize PAR.•Numerous phosphate groups of hyper-branched PAR combined large amount of MB molecule, increasing the detection sensitivity.•This electrochemical biosensor has been applied to detect PARP-1 in in IOSE80 and MCF-7 cells. Early diagnosis of tumors is becoming increasingly important in modern healthcare. As studies have demonstrated, Poly(ADP)ribose polymerase-1 (PARP-1) is overexpressed in more aggressive tumors. Consequently, sensitive detection of PARP-1 activity holds significant practical importance in clinical diagnostics and biomedical research. Herein, an electrochemical biosensor for the sensitive monitoring of the PARP-1 activity have been proposed. The presence of target PARP-1 firstly triggers enzyme-initiated auto-PARylation and formed negatively charged polymer consisting of a few to 200 ADP-ribose units. Due to electrostatic adsorption, negatively charged PAR will bind with a large number of positively charged methylene blue (MB) electroactive molecules. By detecting the electrochemical signal of MB on the indium tin oxide (ITO) electrode, PARP-1 activity detection was achieved with a linear detection range of 0–1.0 U and a detection limit as low as 0.003 U. The proposed biosensor shows great prospects of clinical application.