Photoelectrochemical Cytosensing of RAW264.7 Macrophage Cells Based on a TiO2 Nanoneedls@MoO3 Array.

We have developed a photoelectrochemical (PEC) cytosensor for ultrasensitive detection of RAW264.7 cells by the signal change of a TiO2 nanoneedles (NNs)@MoO3 array. For the first time, a TiO2 NNs@MoO3 array was adopted for the fabrication of the cytosensor for the signal output. The well-matched alignment of TiO2 NNs and MoO3 efficiently suppresses the recombination of photogenerated electron and hole (e-/h+) pairs for improved photon-to-current conversion efficiency. The RAW264.7 cell and F4/80 antibody could form the biocomplexes because of the specific recognition between each other. The constructed PEC cytosensor based on the TiO2 NNs@MoO3 array displayed good PEC property for detection of RAW264.7 cells. The numbers of RAW264.7 cells are directly detected through the decrement of photocurrent intensity, due to the increased steric hindrance when RAW264.7 cells are captured. The PEC cytosensor showed an ultrasensitive response to RAW264.7 cells with a linear range of 50-15 000 cells/mL and a detection limit of 50 cells/mL. The designed cytosensor based on a TiO2 NNs@MoO3 array offers an ideal platform to detect RAW264.7 cells with excellent stability, reproducibility, and selectivity and served as a model for the fabrication of cytosensors for other cells.