Conjugated Polymer-Based Photoelectrochemical Cytosensor with Turn-On Enable Signal for Sensitive Cell Detection

In this work, a new photoelectrochemical (PEC) cytosensor was constructed by using cationic polyfluorene derivative, poly(9,9-bis(6′-(N,N,N,-trimethylammonium)hexyl)fluorene-co-alt-1,4-phenylene)bromide (PFP) as the photoelectric-responsive material for sensitive cell detection. Positive-charged PFP with high photoelectric conversion efficiency can generate robust photocurrent under light illumination. In the PEC cytosensor, 3-phosphonopropionic acid was linked to the indium tin oxide electrode, followed by modification with antiepithelial-cell-adhesion-molecule (EpCAM) antibody via amide condensation reaction. Thus, target SKBR-3 cells with overexpressed EpCAM antigen could be captured onto the electrode via the specific antibody–antigen interactions. Upon adding cationic PFP, a favorable electrostatic interaction between cationic PFP and negatively charged cell membrane led to a turn-on detection signal for target SKBR-3 cells. This new cytosensor not only exhibits good sensitivity because of the good p...