Highly sensitive detection of Brucella in milk by cysteamine functionalized nanogold/4-Mercaptobenzoic acid electrochemical biosensor

To effectively cut off the transmission of Brucella to humans through milk, a novel biosensor for detection of Brucella was constructed using cysteamine functionalized nanogold (Cys-Au) and 4-Mercaptobenzoic acid (4-MBA) modified gold electrode as the platform. The morphology of the prepared nanomaterials was characterized by laser particle sizer, XPS and SEM, and the results showed the 4-MBA film was modified on the gold electrode surface, and the diameter of successfully prepared nanogold and Cys-Au are about 55 and 65 nm, respectively. The electrochemical performance of the biosensor was tested in Brucella antigen solution by square wave voltammetry (SWV). The results showed the reproducibility and stability of the biosensor were good, the spiked recovery in milk was in the range of 95.12–105.27%, and the minimum detection limit (S/N = 3) was 5.12 × 102 cfu/mL with a linear range from 1.6 × 102 to 1.6 × 108 cfu/mL. In addition, the minimum detection limit was reduced from 5.12 × 102 cfu/mL to 7.0 × 101 cfu/mL after processing the SWV data by second-order derivative transformation, which showed Second-order derivative transformation is very helpful to further optimize the performance of the sensor. Compared with the previously reported test methods, the prepared biosensors have a wider linear range and lower limit of detection (LOD). Therefore, the constructed biosensor can be used as a promising tool for the trace detection of Brucella in milk samples.