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.