Single-drop electrochemical immunosensor with 3D-printed magnetic attachment for onsite smartphone detection of amoxicillin in raw milk

Amoxicillin is a beta-lactam group of antibiotics used against bacterial infections. The growth of the antibiotic market and abuse of amoxicillin led to its accumulation in nature, especially in foods. Thus, rapid amoxicillin tests are needed to protect human health and increase food safety. In this study, a single drop, mobile electrochemical amoxicillin immunosensor was developed for the first time. The immunosensor platform is based on amoxicillin antibodies conjugated magnetic nanoparticles. A 3-Dimensional (3D) cell capable of accumulating amoxicillin molecules, which interact with antibody-conjugated magnetic nanoparticles on the electrode surface was designed and 3D-printed. A small potentiostat connected to an Android mobile phone was used to detect amoxicillin in a single-drop raw milk sample in a 3D-printed cell. Results demonstrated linearity between 0.5 and 100 mu M with an LOD of 0.44 mu M. Due to its rapid and portable application, the designed immunosensor shows good potential in on-site amoxicillin detection from milk samples.