Immobilization of the enzyme β-lactamase by self-assembly on thin films of a poly(phenyleneethynylene) sequenced with flexible segments containing sulfur atoms

A novel poly(phenyleneethynylene) sequenced in the main conjugated chain with flexible groups containing sulfur atoms has been synthesized by Heck–Sonogashira coupling reaction. Layer-by-layer films of the polymer have been prepared with a linear growth in thickness up to four layers as evidenced by UV–Vis spectroscopy and perfilometry. On the top of these multilayers, the enzyme β-lactamase was deposited by self-assembly. The enzymatic activity was measured by a modified spectrophotometric standard assay method for penicillin G, ampicillin and amoxicillin. A higher and faster activity was obtained for penicillin G and thus preliminary study of the biosensor response by fluorescence was carried out for this antibiotic revealing a decrease in the polymer fluorescence as function of the penicillin G concentration.