Perylene tetracarboxylic acid (PTA)-based type II heterojunction sensing platform for signal-on photoelectrochemical detection of CEA

The construction of robust photoelectrochemical (PEC) transducing platforms mediates the feasibility and performance of the PEC biosensors. In this work, perylene tetracarboxylic acid (PTA) nanoassemblies were exploited as robust semiconductors to form type II heterojunctions with In2O3. The prepared organic/inorganic heterojunctions show high PEC transducing performances. The carboxyl groups of PTA avoid the additional surface functionalization for covalent immobilization of capturing elements which will diminish the transducing performance. This enables the facile construction of PEC immunosensing platforms. More importantly, Ag@CeO2 nanoparticles were used as energy level matching nanolabels to develop a signal-on PEC immunosensing method. A linear response from 0.1 pg/mL to 100 ng/mL with a detection limit of 63.1 fg/mL was achieved for a typical protein biomarker carcinoembryonic antigen (CEA).