Fluorescently tagged star polymers by living radical polymerisation for mucoadhesion and bioadhesion

The synthesis of 3-, 5- and 8-arm dimethylaminoethyl methacrylate star polymers are reported, final Mn (PDI) = 12.2 K (1.09), 18.9K (1.10) and 38.4 K (1.11), respectively. The synthesis of 3-arm methyl methacrylate and dimethylaminoethyl methacrylate block co-polymer stars is also described. Living polymerisation occurred in all cases providing well defined stars with predictable molecular weights and narrow polydispersity. A fluorescent tag, 2-(8-methacryloyloy-3,6-dioxaoctyl)thioxantheno[2,1,9-dej]isoquinoline-1,3-dione, derived from a commercially available pigment, was incorporated into the star polymers. The fluorescence spectra of the polymers prepared were recorded over a range of pH and the peak emission frequency and intensity have been reported, λex = 462 nm. All of the multi-arm polymers exhibit fluorescence across a broad pH range with maximum emission at pH 4. A 3-arm star polymer has been demonstrated to show good bioadhesion in rat tissue. A reduced adhesion in epithelial tissues not covered by a viscoelastic mucus gel indicates an increased tendency for mucoadhesion over bioadhesion.