Synthesis of sodium thiosulfate-reduced copper nanoclusters using bovine serum albumin as a template and their applications in the fluorometric detection of minocycline

A green and facile strategy for the synthesis of copper nanoclusters (CuNCs) is developed using Na2S2O3 as a reducing agent and bovine serum albumin as a template. The CuNCs are characterized by ultraviolet–visible, fluorescence and infrared spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. When excited at 336 nm, a strong characteristic peak of fluorescence emission is found at 407 nm. Transmission electron microscopy shows that the obtained CuNCs exhibit a spherical shape with an average diameter of ~2 nm. In addition, the CuNCs exhibit excellent water solubility and stability. Subsequently, a fluorescence method for determining minocycline (MC) is established based on the effective fluorescence quenching of CuNCs by MC attributed to the inner filter effect. The linear range is from 1.00 to 100 μM with a detection limit of 0.76 μM. Selectivity and anti-interference studies indicate that the nanoprobe presents good selectivity over other substances, including biomolecules and inorganic ions. The method is successfully used for MC detection in urine and plasma samples. Therefore, the proposed fluorescence strategy based on CuNCs can provide a convenient platform for the detection of MC in biomedical applications.