Faster accurate fluorometric biosensing of E. coli by preconcentration on a green-synthesized Ag/Fe 3 O 4 /chitosan nanocomposite

Simple, rapid and sensitive detection assay using magnetic Ag/Fe 3 O 4 /Chitosan (Ag@IO@CS) nanocomposite, was developed for efficient removal, preconcentration and fluorometric determination of trace amounts of Escherichia coli (E. coli) bacteria. For the first time, preconcentration on the green prepared nanocomposite was combined with fluorometric detection to quantify ultralow concentrations of E. coli, and several parameters of the proposed methodology were investigated. Combination of nanocomposite adsorption and magnetic separation was used to easily extraction followed by desorption of bacteria, therefore E. coli could be determined even in the presence of gram-positive interfering bacteria. A chemometric approach was used for the analysis of fluorescence data of different bacteria to show the non-disturbance of the interferences as well. Stable magnetic silver and chitosan nanocomposite showed outstanding physical and chemical properties of consisting nanomaterials besides magnetic separation capability that make this nanobiosensor excellent scaffolds for the construction of the unique probe for E. coli bacteria.