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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. [ABSTRACT FROM AUTHOR]

A competitive electrochemical aptamer biosensor for the selective detection of Pb2+ was developed in this study. The PAMAM@Au hybrid materials and the bioprobe MB-GNPs-ssDNA were synthesized with chemical methods. Modified electrode with carboxylated graphene oxide was prepared via electrodeposition. PAMAM@Au was immobilized on the modified electrode using the EDC/NHS crosslinker, and aptamer (Apt) was bound to PAMAM@Au hybrid materials using the glutaraldehyde crosslinker. The assembly of MB-GNPs-ssDNA/Apt/PAMAM@Au/GO/SPCE biosensors was achieved through immobilizing bioprobe onto electrodes, based on the theory of aptamer-complementary chain reactions. The fabricated biosensor was characterized through electrochemical experiments, SEM, AFM, TEM, XPS and FTIR. The biosensor's performance was evaluated in a series of Pb2+ aqueous solutions by differential pulse voltammetry (DPV), and the results demonstrated this biosensor had excellent repeatability, stability, and specificity. The detection range spanned from 0.5 pM/L to 500 nM/L, with a detection limit of 5 fM/L. Consequently, the proposed biosensor can serve as a reliable analytical tool for the sensitive detection of lead ions. • A novel competitive electrochemical aptamer biosensor for detecting lead ions was Designed. • The polyamidoamine (PAMAM) dendrimer encapsulated with nanogold was innovatively synthesized. • A biosignal probe MB-GNPs-ssDNA for enhancing the detection signal of biosensor was synthesized. • The redox property of methylene blue was employed to generate a detectable electrical signal. [ABSTRACT FROM AUTHOR]

The detection of harmful components in food is of paramount importance in the light of recent food safety incidents caused by foodborne pathogenic bacteria. Aptamer electrochemical biosensors are novel biosensors that use electrode modifications to immobilise aptamers, the biological recognition elements, and then use electrochemical techniques to detect the generated electrical signals. Compared with traditional detection methods, electrochemical aptamer sensors have the advantages of high specificity, high sensitivity, and low cost and have been widely used to detect hazardous components in food. This review summarises these sensors′ current research status and problems in detecting common foodborne pathogenic bacteria and provides an outlook on their development trends. [ABSTRACT FROM AUTHOR]