A sensitive fluorescence turn-off-on biosensor for poly(ADP-ribose) polymerase-1 detection based on cationic conjugated polymer-MnO2 nanosheets

Poly(ADP-ribose) polymerase-1 (PARP-1) monitoring has attracted extensive attention because it serves a vital role in human pathologies. However, only a few researches about its detection methods have been reported because PARP-1 and its catalyzed product poly(ADP-ribose) polymer (PAR) are lack of optical or electrochemical activity. Herein, a convenient fluorescence turn-off-on nanosensor based on cationic conjugated polymer (PFP) and MnO2 nanosheets has been designed for selective detection of PARP-1 in vitro. To the best of our knowledge, it is the first time to use manganese dioxide (MnO2) nanosheets for PARP-1 detection. The fluorescence intensity of PFP can be quenched by MnO2 nanosheets via a fluorescence resonance energy transfer (FRET). While the subsequently joined electronegative poly(ADP-ribose) polymer (PAR), catalysate of PARP-1, take positively charged MnO2 nanosheets away from PFP via electrostatic interaction, causing sufficient recovery of fluorescent signal. The sensing platform displayed a sensitive response to PARP-1 in a linear range of 0.03 - 1.5 U (0.024 - 1.2 nM), with a detection limit of 0.004 U (0.003 nM), which is 10-100 lower than reported methods. As expected, this method was successfully applied to the detection of PARP-1 in human serum samples with recoveries ranging from 97.6 - 102.7%. Especially, it has also been applied to the determination of PARP-1 in human breast cancer cells SK-BR-3 in the 40 to 1000 cells per mL range, with a detection limit as low as 25 cells per mL.