Supersensitive Photoelectrochemical Aptasensor Based on Br,N-Codoped TiO₂ Sensitized by Quantum Dots

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Carcinoembryonic antigen (CEA) is a significant cancer biomarker.
• Developing sensitive and efficient detection methods for CEA is crucial for early cancer diagnosis.
• Existing photoelectrochemical (PEC) sensors face limitations in sensitivity and efficiency.

Purpose of the Study:

• To fabricate a novel PEC aptasensor for supersensitive CEA detection.
• To enhance the energy level arrangement and photoelectric conversion efficiency using a Br,N-codoped TiO2/CdS QDs sensitization structure.
• To establish a new strategy for highly sensitive PEC biomolecule detection.

Main Methods:

• Fabrication of Br,N-codoped TiO2 with reduced energy bandwidth (2.88 eV) and broadened light absorption (400-700 nm).
• Construction of a Br,N-codoped TiO2/CdS QDs sensitization structure for enhanced photocurrent signal.
• Utilizing an exonuclease III (Exo-III)-assisted cycle strategy for signal amplification.
• Optimization of conditions for the PEC aptasensor.

Main Results:

• The Br,N-codoped TiO2/CdS QDs structure exhibited improved electron transfer and photoelectric conversion efficiency.
• The aptasensor achieved a wide detection range for CEA from 1 fg/mL to 1 ng/mL.
• A remarkably low limit of detection (LOD) of 0.46 fg/mL for CEA was obtained.

Conclusions:

• The developed PEC aptasensor demonstrates superior performance for CEA detection.
• The novel photoactive material and sensing strategy significantly enhance photoelectric conversion efficiency.
• This work provides a new pathway for highly sensitive PEC detection of biomolecules.