Label-free photoelectrochemical immunosensing of α-fetoprotein based on Eu-TiO2 nanocomposites sensitized with dye-encapsulated HMA

In this study, a sensitive photoelectrochemical immunosensor with dye-enhanced anodic photocurrent response was proposed for sensitive detection of α-fetoprotein (AFP). Specifically, europium-doped TiO2 (Eu-TiO2) was used as the photoelectrochemical functional material and coated onto indium tin oxide (ITO) electrode. Doxorubicin (DOX) as an excellent fluorescent dye was encapsulated in the hydrophobically modified alginate (HMA). Then the dye-loaded HMA was modified onto the surface of Eu-TiO2 to further sensitize the photocurrent response. The results showed that the photoelectrical signal was enhanced and stabilized due to the effect of sensitization of DOX on Eu-TiO2 material. The constructed PEC sensor revealed a good linear response to AFP antigen ranging from 0.5 to 100 ng/mL with a detection limit of 0.41 pg/mL. The clinical patient’s serum test results obtained from the proposed PEC immunosensor were consistent with those obtained from the commercial electrochemilunescence assay. The proposed PEC sensing method could be a promising analytical tool for the detection of AFP in clinical analysis.