Accurate
measurement of cancer markers in urine is a convenient
method for tumor monitoring. However, the concentration of cancer
markers in urine is so low that it is difficult to achieve their measurement.
Photoelectrochemical (PEC) sensors are a promising technology to realize
the detection of trace cancer markers due to their high sensitivity.
Currently, the interference of nonspecific biomolecules in urine is
the main reason affecting the high sensitivity and selectivity of
PEC sensors in detecting cancer markers. In this work, a strategy
of oxygen vacancy (OV) modulation is proposed to construct a fouling-resistant
PEC aptamer sensing platform for the detection of α-fetoprotein
(AFP), a liver cancer marker. The introduction of OVs induces the
formation of intermediate localized states in the photoelectric material,
which not only facilitates the separation of photogenerated carriers
but also leads to the redshift of the light absorption edge. More
importantly, OVs with positive electrical properties can be employed
to modify the antifouling layer (C-PEG) with negatively charged groups
through an electrostatic interaction. The synergistic effect of OVs,
antifouling layer, and aptamer resulted in a TiO2/OVs/C-PEG-based
PEC sensor achieves a wide linear range from 1 pg/mL to 100 ng/mL
and a low detection limit of 0.3 pg/mL for AFP. In addition, the sensor
successfully realized the determination of AFP in urine samples and
accurately differentiated between normal people and liver cancer patients
in the early and advanced stages. This project is of great significance
in advancing the application of photoelectrochemical bioanalytical
technology to achieve the detection of cancer markers in urine by
investigating the construction of an OVs-regulated fouling-resistant
sensing interface.