title: Stabilization of neutral polyfluorene in aqueous solution through their interaction with phospholipids and sol-gel encapsulation.
abstract: Interaction between poly[9,9-bis(6'-bromohexyl)-2,7-fluorene-co-alt-1,4-phenylene] (PFPBr2), a neutral conjugated polyfluorene which is completely insoluble in water, and zwitterionic phospholipids has been investigated in order to generate new fluorescent structures which are stable in aqueous media as a means of extending the biological applications of these kinds of polymers. Two types of differently shaped and composed fluorescent structures were identified and then isolated and characterized separately using different biophysical techniques. The first structure type, corresponding to liposomal complexes, showed a fluorescence band centered around 405 nm and maximum absorption at 345 nm, while the second, corresponding to polymer-phospholipid aggregates of variable sizes with lower lipid content, absorbed at longer wavelengths and displayed a well resolved fluorescence spectrum with a maximum centered at 424 nm. Both structures were stable in a large range of pH, and their fluorescence intensity remained practically unaltered for 10 days; it then began to decrease, which was probably because of aggregation. Encapsulation of these structures within the pores of a sol-gel matrix did not affect their fluorescent properties but increased their stability, avoiding further aggregation and subsequent precipitation.
authors.affiliation: Instituto de Biología Molecular y Celular, Universidad Miguel Hernández de Elche, Edificio Torregaitán. Avda. de la Universidad s/n, Alicante 03202, Elche, Spain. r.mallavia@umh.es
authors.forename: Ricardo
authors.initials: R
authors.lastname: Mallavia
authors.forename: Maria José
authors.initials: MJ
authors.lastname: Martínez-Tomé
authors.forename: Rebeca
authors.initials: R
authors.lastname: Vázquez-Guilló
authors.forename: Zehra
authors.initials: Z
authors.lastname: Kahveci
authors.forename: Amparo
authors.initials: A
authors.lastname: Estepa
authors.forename: C Reyes
authors.initials: CR
authors.lastname: Mateo
mesh_terms: D005449:Fluorenes / Q000737:chemistry*; D005782:Gels / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008081:Liposomes / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry*
chemical_list: D005449:Fluorenes; D005782:Gels; D008081:Liposomes; D010743:Phospholipids; D011108:Polymers