Development of a new dual electrochemical immunosensor for a rapid and sensitive detection of enrofloxacin in meat samples.

A novel dual electrochemical immunosensor was fabricated for the rapid and sensitive detection of enrofloxacin (EF) antibiotic in meat. Anti-quinolone antibody was immobilized onto screen-printed dual carbon electrodes via carbodiimide coupling. A new electrochemical probe was synthesized by conjugating difloxacin and aminoferrocene, whose oxidation was measured at + 0.2 V vs. Ag/AgCl by differential pulse voltammetry. The detection principle was based on the competitive binding of this conjugate and free EF on immobilized antibodies. The proposed immunosensor allowed detection of EF at concentrations ranging from 0.005 µg.mL-1 to 0.01 µg.mL-1 with a detection limit of 0.003 µg.mL-1. The immunosensor was stable for at least 1 month at 4 °C and displayed a good specificity for other fluoroquinolones. The new dual electrode design offered an improved accuracy as one electrode was used as negative control. The efficiency of the sensor and the adequacy of the extraction process were finally validated by detecting EF in different meat samples.

Innovative Electrochemical Screening Allows Transketolase Inhibitors to Be Identified.

Transketolases (TKs) are ubiquitous thiamine pyrophosphate (TPP)-dependent enzymes of the nonoxidative branch of the pentose phosphate pathway. They are considered as interesting therapeutic targets in numerous diseases and infections (e.g., cancer, tuberculosis, malaria), for which it is important to find specific and efficient inhibitors. Current TK assays require important amounts of enzyme, are time-consuming, and are not specific. Here, we report a new high throughput electrochemical assay based on the oxidative trapping of the TK-TPP intermediate. After electrode characterization, the enzyme loading, electrochemical protocol, and substrate concentration were optimized. Finally, 96 electrochemical assays could be performed in parallel in only 7 min, which allows a rapid screening of TK inhibitors. Then, 1360 molecules of an in-house chemical library were screened and one early lead compound was identified to inhibit TK from E. coli with an IC50 of 63 µM and an inhibition constant ( KI) of 3.4 µM. The electrochemical assay was also used to propose an inhibition mechanism.