Delicate photoelectrochemical sensor for folic acid based on carbon nanohorns supported interwoven titanate nanotubes

Herein, a signal-amplified photoelectrochemical sensing platform based on interwoven titanate nanotubes and carbon nanohorns conjugates was constructed for folic acid determination. Specifically, titanate nanotubes with reticulation structure were employed as optoelectronic element, which possessed fine photocatalytic activity and enhancement in facilitating fast and long-distance electron transport. Hierarchical-structured carbon nanohorns were introduced as the mainstay to provide as the electron-transport medium to capture and transmit electrons from excited titanate nanotubes to the sensing matrix owing to the prominent conductivity and large surface. Furthermore, the holes from valence band of stimulated titanate nanotubes could transfer to their surface and be consumed by folic acid, thus enhancing the photocurrent response. Hence, under the optimal conditions, a linear relationship between photocurrent increase and logarithm concentration of folic acid was obtained in the wide range from 1 × 10−10 to 5 × 10−5 M with a detection limit of (2.5 ± 0.005) × 10−11 M. The well-designed transducer showed practical advantages, such as universality, simplicity and convenience, opening up a valuable application for other important molecules assessment.