Toward new fluorescent bioinspired sensors: interaction of poly(fluorene-phenylene) with phospholipid bilayers

Abstract

Most of the conjugated polymer employed as fluorescent biosensors present low solubility and emission in aqueous environment. In order to solve this feature, we have reconstituted, in buffer phosphate, a neutral conjugated poly[9,9-bis(6'-bromohexil)-2,7-fluorene-co-alt-1,4-phenylene], as PFPBr 2 (insoluble in water), in the presence of an artificial zwitterionic phospholipids bilayers, as 1,2-dimyristoyl-sn-glycero-3-phospho-choline (DMPC). Quantum yield of PFPBr 2 -DMPC was around 20% in phosphate buffer, it was identical value calculated from ammonium polyelectrolytes (PFPNMe 3+ ). In addition, the maximum of bluish emission for buffer solution of PFPBr 2 -DMPC was at 420nm, a redshift emission with regard to chloroform solution (at 410 nm). The structural study at different concentrations of PFPBr 2 and DMPC was carried out using different approaches: steady state fluorescence spectroscopy, confocal fluorescence microscopy and calorimetry. A positive interaction takes place involving neutral conjugated polymer and zwitterionic phospholipids bilayer. Novels complexes or associations of poly(fluorene-phenylene) (PFPBr 2 ) and zwitterionic phospholipids (DMPC) have been suggested and visualized by epifluorescence. Phase transitions of the liposomes have been also detected by differential scanning calorimetry.

Stabilization of Neutral Polyfluorene in Aqueous Solution through Their Interaction with Phospholipids and Sol–Gel Encapsulation

“…For this reason, phospholipids could be considered as ideal candidates to interact with nonpolar polyfluorenes so as to form fluorescent complexes which are stable in aqueous environments. The existence of interactions between phospholipids and neutral polyfluorenes has recently been reported by our group and by Tapia et al…”

“…A stock solution of DMPC was prepared in chloroform, in the absence or presence of PFPBr 2 , at an adequate polymer-to-lipid molar ratio (1:5) . Chloroform solutions were then dried under a stream of argon to obtain a thin film at the bottom of a small thick-walled glass tube.…”

β-Phase Formation of Poly(9,9-dioctylfluorene) Induced by Liposome Phospholipid Bilayers

“…PFO is a neutral polymer (Figure ) which can only be taken into aqueous systems through interaction with amphiphiles, such as phospholipids, as has previously been indicated for the neutral poly[9,9-bis(6′-bromohexyl)-2,7-fluorene-co-alt-1,4-phenylene], PFPBr 2 , in DMPC liposomes …”

“…PFO is a neutral polymer (Figure 1) which can only be taken into aqueous systems through interaction with amphiphiles, such as phospholipids, as has previously been indicated for the neutral poly[9,9-bis(6 0 -bromohexyl)-2,7-fluorene-co-alt-1,4-phenylene], PFPBr 2 , in DMPC liposomes. 27 Normalized corrected absorption and emission spectra of PFO in DMPC liposomes are shown in Figure 2A. Scattering background from the liposomes was corrected by subtracting the apparent absorption of free liposomes from those with PFO, normalized at 500 nm.…”

pH and ion-species sensitive fluorescence properties of star polyelectrolytes containing a triphenylene core

“…1,2 Conjugated polyelectrolytes (CPs) have been developed as sensors because their fluorescence properties are highly sensitive to minor perturbations of the local microenvironment. [3][4][5][6] In comparison with CPs, small fluorescent molecules grafted with polyelectrolyte chains are expected to have a better solubility in aqueous solutions and can be more easily developed into aqueous sensing systems. 7,8 However, only a few studies have been performed on such systems, [9][10][11] and the exact mechanism that how the intramolecular and intermolecular interactions influence the fluorescence properties remains unclear.…”