A self‐powered photoelectrochemical aptasensor using 3D‐carbon nitride and carbon‐based metal‐organic frameworks for high‐sensitivity detection of tetracycline in milk and water

Abstract Antibiotic residues have become a significant challenge in food safety, threatening both ecosystem integrity and human health. To combat this problem, we developed an innovative photo‐powered, self‐powered aptasensor that employs a novel carbon‐doped three‐dimensional graphitic carbon nitride (3D‐CN) combined with a metal‐organic framework composed of N‐doped copper(I) oxide‐carbon (Cu 2 O@C) skeletons. The 3D‐CN serves as the photoanode, offering stable photocurrent production due to its three‐dimensional open framework structure. The N‐doped Cu 2 O@C acts as the photocathode, providing oxidation protection for the metal core and enhancing light absorption due to its metal‐organic framework structure. A key feature of our work is exploiting the Fermi level difference between the n‐type photoanode and p‐type photocathode, which facilitates faster migration of photogenerated electrons toward the photocathode, thereby enhancing the sensor's self‐powered effect. Experimental results reveal that upon aptamer loading, the sensor can linearly detect tetracycline (TC) within a range of 0.5 pmol/L to 300 nmol/L, with a detection limit as low as 0.13 pmol/L. It also demonstrates excellent selectivity, stability, and reproducibility, making it applicable to real samples such as milk and river water. Consequently, our research provides a highly efficient and sensitive method for monitoring TC in food, with significant practical implications and profound impacts on food safety.