Iron oxide@mesoporous carbon architectures derived from an Fe(II)-based metal organic framework for highly sensitive oxytetracycline determination

A series of nanocomposites comprised of iron oxide and mesoporous carbon (denoted as Fe3O4@mC) were derived from an Fe(II)-based metal–organic framework (525-MOF) by calcining at different temperatures. The advantages of chemical functionality, strong bioaffinity, and high stability of the Fe3O4@mC can be combined with the high specific surface area of 525-MOF leading to the formation of Fe3O4@mC nanocomposites as a scaffold for oxytetracycline (OTC) aptamer strands. The use of Fe3O4@mC nanocomposites reveals high OTC detection efficiency. The nanocomposite calcined at 900 °C (denoted as Fe3O4@mC900) is found to be the best candidate toward high-sensitivity and high-selectivity detection of OTC because of its excellent functionality, nanostructural properties, and high electrochemical performance. Accordingly, the Fe3O4@mC900-based electrochemical aptasensor displays high sensitivity with a low detection limit of 0.027 pg mL−1 within a broad linear range of OTC concentration from 0.005 to 1.0 ng mL−1. The aptasensor also exhibits high selectivity, reproducibility, stability, regenerability, and applicability in milk samples. All of these results indicate that the Fe3O4@mC nanocomposites that originated from 525-MOF can be applied in the fields of trace and fast antibiotic determination.