Photoelectrochemical aptasensor for ultrasensitive detection of MUC1 based on titanium dioxide/polypyrrole/carboxy polyethylene glycol hybrid anti-fouling interface.

Achieving ultrasensitive detection of MUC1 in the early stages of breast cancer is critical for reducing mortality and improving patient prognoses. Photoelectrochemical sensing has emerged as a promising technology for the detection of MUC1, primarily due to its straightforward operation and user-friendly instrumentation. However, titanium dioxide, a commonly used photoactive material, exhibits inherent limitations, including low charge carrier mobility and challenges related to non-specific adsorption in complex biological matrices. These issues significantly undermine the sensitivity of MUC1 detection, underscoring the urgent need for improved photoactive materials and sensing methodologies. Herein, we proposed a novel PEC aptasensor engineered with titanium dioxide/polypyrrole/carboxy polyethylene glycol (TNWs/PPy/C-PEG) hybrid anti-fouling interface via facile self-assembly. The composite of titanium dioxide nanowires and polypyrrole forms a heterojunction (TNWs/PPy) that extends the electron lifetime to 38.0 ms while significantly improving light utilization, carrier mobility, and photoelectric conversion efficiency. This enhancement ultimately amplifies the photoelectric current response. Furthermore, the negatively charged C-PEG anti-fouling unit is electrostatically anchored to the positively charged TNWs/PPy electrode surface, effectively preventing the adsorption of non-specific contaminants. Ultimately, MUC1 aptamers are immobilized on the TNWs/PPy/C-PEG photoelectrode, facilitating the selective capture of MUC1. The synergistic effects of TNWs/PPy electrode, specific recognition units, and anti-fouling layer led to a marked improvement in the selectivity and sensitivity. The detection limit of this aptasensor is 0.33 pg mL-1, with a linear range from 1 pg mL-1 to 500 ng mL-1. Furthermore, satisfactory results were obtained in the measurement of MUC1 in serum samples. The electrostatic self-assembly strategy presents a straightforward and novel approach to ensuring the stability of anti-fouling sensing interfaces. Moreover, the incorporation of heterojunction formation for signal amplification, in conjunction with the synergistic construction of anti-fouling interfaces, offers an innovative solution for the development of advanced sensing platforms and the early detection of breast cancer.