Label-free poly(ADP-ribose) polymerase-1 activity assay based on perpendicular orientated mesoporous silica films

Since the expression of poly(ADP-ribose) polymerase-1 (PARP-1) was significantly up-regulated in several primary malignancies, it was important to construct a sensitive and rapid PARP-1 assay for early diagnosis of cancer. When PARP-1 was activated by active dsDNA, it generates a number of negatively charged poly(ADP-ribose) (PAR) polymers, which can be readily detected. Here, we developed a label-free electrochemical (EC) biosensor for PARP-1 activity based on the electrostatic attraction between negatively charged PAR and positively charged amino-functioned mesoporous silica films (NH 2 -MSFs). Negatively charged PAR was absorbed on the NH 2 -MSFs surface and suppressed the electrochemical signal as the PAR prevented the electroactive probe reaching to the ITO electrode. The electrochemical signal for PAR linearly decreased from 0.01 U to 1.2 U with a detection limit of 0.005 U, which is comparable to the PARP-1 biosensors reported before. The strategy has been used to evaluate PARP-1 inhibitors and to detect PARP-1 activity in human serum and real cancer cells lysate with satisfactory results, indicating that it was a promising candidate for point-of-care diagnostics.