Photoelectrochemical aptasensor for sensitively detecting S-Propranolol based on Au NPs modified g-C3N4/BiPO4 heterojunction

Propranolol , a widely used β-adrenergic receptor antagonist drug with potential toxic effects to organisms and human beings, was not completely removed from environment through traditional wastewater treatments . It is necessary to sensitively and selectively monitor the trace content propranolol in various samples. In this work, a novel photoelectrochemical (PEC) aptasensor based on Au nanoparticles (NPs) modified g-C 3 N 4 /BiPO 4 heterojunction was successfully fabricated for detecting (S)-propranolol (S-Pro), an important racemic enantiomer of propranolol. Herein, g-C 3 N 4 was employed as visible light-active semiconductor. The photocatalytic activity of g-C 3 N 4 was enhanced via forming heterojunction with BiPO 4 to facilitate the separation and migration of photogenerated carriers . In addition, Au NPs with perfect conductivity and surface plasmon resonance (SPR) effect are not only beneficial to the electron transfer and visible light harvest of g-C 3 N 4 /BiPO 4 heterojunction, but also the crucial factor on assembling S-Pro-binding DNA aptamer via Au-S bonding. At the same time, as a π-π conjugated material, g-C 3 N 4 with large surface area also provides an excellent platform for loading Au NPs. Under the visible light illumination, the PEC aptasensor displayed high PEC performance. On such a sensor, specific captured S-Pro by the aptamer was quickly oxidized by the photogenerated holes to inhibit the recombination of the photogenerated carriers, enhanced the PEC response, and realized the detection of S-Pro. Under optimal conditions, the designed PEC aptasensor exhibited a wide linear range of 10 nM to 1000 nM with a low detection limit (defined as S/N = 3) of 2.55 nM. Moreover, the proposed sensor displayed high selectivity , good reproducibility, and general long-term stability. And the S-Pro in real sample was accurately detected using this proposed sensor.