Hybrid silica–polyelectrolyte films as optical sensing materials for tetracycline antibiotics

•Silica–polyelectrolyte hybrid films modified with Eu(III) are worked out.•Their morphology and sorption capacity are function of silica sol composition.•Sensor element for detection of Tc based on Eu-sensitized fluorescence is obtained.•The fluorescence doubled in the presence of citrate ion.

Optical sensor element for the determination of tetracycline (Tc) based on europium-sensitized luminescence of the SiO2–polyelectrolyte (PE)–Eu(III) hybrid film was worked out. The morphology of the hybrid films and their adsorption capacity towards Tc were function of PE and non-ionic surfactants content in silica coating solution. The presence of a mixture of Tween 20 and triblock copolymer Pluronic F-127 in a molar ratio Tween 20:Pluronic F-127 = 35:2.5 in silica sol resulted in the formation of films with uniform and ordered mesoporous structure. The use of polyvinyl- and polystyrene sulfonic acids during sol–gel synthesis greatly increased Tc adsorption within the hybrid films. SiO2–PE–Eu(III) films were used for Tc determination in milk with a linear response range in 0.6–10 μmol L−1and LOD 0.3 μmol L−1 of Tc. The sensitivity and selectivity of determination increased in the presence of citrate ions in solution.

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