Rapid and sensitive in-situ detection of polar antibiotics in water using a disposable Ag-graphene sensor based on electrophoretic preconcentration and surface-enhanced Raman spectroscopy

A disposable Ag-graphene sensor was developed for rapid and sensitive in-situ detection of polar antibiotics in water using electrophoretic preconcentration (EP) and surface-enhanced Raman spectroscopy (SERS). The Ag-graphene sensor was fabricated by depositing Ag-graphene nanocomposites synthesized through a facile one-pot method on the disposable screen-printed electrodes (SPEs) and characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM). SERS properties and detection applicability of the developed sensor were systematically investigated. It is shown that the polar antibiotics can be selectively adsorbed on the oppositely charged sensors after applying different potentials during the EP procedure, and the SERS signals of antibiotics with an effective amplification can be achieved with proper time of preconcentration. Moreover, the Ag-graphene sensor could facilitate the molecule adsorption through weak π-π interactions between graphene and antibiotics, further improving the sensitivity of SERS detection. Under the optimum EP conditions, the representative SERS spectra of a mixed solution containing four different antibiotics can be obtained within 10. min, and each antibiotic is easily distinguished by its characteristic peaks with a sub-nM detection level. The results demonstrate that the proposed disposable Ag-graphene sensor based on EP-SERS can be used for rapid and sensitive in-situ detection of polar antibiotics in aqueous samples without a pre-separation step.