An amplified photoelectrochemical aptasensor based on Bi2S3/BiFeO3 for ochratoxin A detection

In this paper, an ultrasensitive photoelectrochemical aptasensor based on amplified signal strategy and competitive mechanism for ochratoxin A (OTA) detection was developed. The prepared photoactive composite material (BiFeO3/Bi2S3) possessed excellent separation ability of photogenerated electron-hole pair and effectively inhibited the recombination of hole and pair, resulting in significantly enhanced photocurrent intensity. The amplified signal strategy was achieved by adding methylene blue (MB), which facilitated electron transfer and improved the photoelectric conversion efficiency. In the presence of OTA, the aptamer can be recognized and captured, the complementary DNA (cDNA) and MB were released from the aptasensor electrode, a decreased photocurrent signal appeared, thus achieving quantitative detection for OTA. Under optimal conditions, the aptasensor exhibited a wide linear relationship range from 10 5 to 10 13 g/mL and a low detection limit of 0.0135 fg/mL (3s/S). Simultaneously, the proposed photoelectrochemical aptasensor also showed excellent accuracy, stability, precision and selectivity.