A Sensitive and Selective Electrochemical Aptasensor Based On Gold Nanoflower/Polyethyleneimine (Pei)-Functionalized Metal Organic Framework Nanocomposites for Label-Free Determination of Streptomycin in Milk Samples

Rapid, accurate, sensitive, and real-time detection of streptomycin (STR) residues in dairy products is very important. In this work, for the first time, the gold nanoflower/polyethyleneimine-functionalized metal organic framework (AuNF-PEI-MIL-101(Cr)) nanocomposites were synthesized via hydrothermal method and characterized using various techniques (SEM, TEM, XRD, FT-IR, and XPS). Then, a novel electrochemical aptasensor was constructed for the detection of STR based on AuNF-PEI-MIL-101(Cr) nanocomposites. The gold electrode (GE) modified with AuNF-PEI-MIL-101(Cr) can immobilize a large number of thiolated STR aptamer via the Au–S bond. When the target STR was in the presence, the current signal was reduced due to the specific binding of STR towards the aptamer. The results indicated that the aptasensor had a wide linear range towards STR (0.01–400 nM) with a low detection limit of 0.003 nM under the optimal conditions. Moreover, the aptasensor exhibited good selectivity, reproducibility, and stability. In addition, the STR in the cow, sheep, and goat milk samples was detected by the spiked recovery method, and satisfactory results were obtained. The method provides an efficient pathway for the sensitive detection of STR.