Signal amplified photoelectrochemical sensing platform with g-C3N4/inverse opal photonic crystal WO3 heterojunction electrode

A novel photoelectrochemical (PEC) aptasensor based on the g-C3N4 nanosheets modified WO3 film with inverse opal photonic crystals (IOPCs) structure was developed. Oxytetracycline (OTC) aptamer was immobilized on the surface of composites through pi-pi interaction between g-C3N4 and DNA nucleotide. Benefiting from the great optical absorption ability and photo-generated charge separation capacity, the g-C3N4/WO3 IOPCs aptasensor exhibited excellent PEC response performance in an electrolyte containing 0.1 M ascorbic Acid (AA). After the recognition and capture of OTC, the configuration change of OTC-aptamer restrained the oxidation of AA by the photogenerated hole on the valance band of g-C3N4, resulting in photocurrent change. The results showed that the PEC aptasensor possessed a linear detection range from 1 nM to 230 nM and a detection limit of 0.12 nM ( approximate to 59.58 ng L-1) for the detection of OTC in water. The satisfactory detection results in real sample further revealed the potential of WO3 IOPCs and its heterostructure for PEC analytical applications, and provided a novel approach for design of PEC platform.