Biological binding processes are often pH-dependent due to the negative charge onto the membrane surface, hence the sorption and the distribution of a drug are strictly connected to the lipophilic nature and the ionization degree under physiological conditions [1, 2, 3]. The pKa values of three pH-sensitive fluorinated phenols, 2,4,6-trifluorophenol (3FP), 2,3,5,6-tetrafluorophenol (4FP) and 2,3,4,5,6-pentafluorophenol (5FP), have been determined at 25°C by using UV-vis and 19F-NMR spectroscopy in aqueous solution. The effect of extruded liposomes formed by the natural zwitterionic phospholipid POPC (1-palmitoyl-2-oleoyl-phosphatidylcholine), the commercial cationic surfactant DDAB (didodecyldimethylammonium bromide) and POPC-DDAB mixed liposomes on the pKa of the probes have been investigated. The probe-liposomes interaction depends on both the equilibrium between the neutral and ionic form of the fluorinated phenols and the charge onto the liposomal surface determined by Zeta Potential measurements in a wide pH range [4]. [1] Mihajlovic, M., Lazaridis, T. J. Phys. Chem. 2006, 110, 3375-3384. [2] Hanakam, F., Gerish, G., Lotz, S., Alt, T., Seeling, A. Biochemistry 1996, 35, 11036-11044. [3] De Alba, E. Weiler, S., Tjandra, N. Biochemistry 2003, 42, 14729-14740. [4] Gasbarri, C., Angelini, G. submitted.

Effect of mixed liposomal systems on the pKa values of fluorinated phenols used as pH-sensitive probes

ANGELINI, Guido;GASBARRI, Carla
2014-01-01

Abstract

Biological binding processes are often pH-dependent due to the negative charge onto the membrane surface, hence the sorption and the distribution of a drug are strictly connected to the lipophilic nature and the ionization degree under physiological conditions [1, 2, 3]. The pKa values of three pH-sensitive fluorinated phenols, 2,4,6-trifluorophenol (3FP), 2,3,5,6-tetrafluorophenol (4FP) and 2,3,4,5,6-pentafluorophenol (5FP), have been determined at 25°C by using UV-vis and 19F-NMR spectroscopy in aqueous solution. The effect of extruded liposomes formed by the natural zwitterionic phospholipid POPC (1-palmitoyl-2-oleoyl-phosphatidylcholine), the commercial cationic surfactant DDAB (didodecyldimethylammonium bromide) and POPC-DDAB mixed liposomes on the pKa of the probes have been investigated. The probe-liposomes interaction depends on both the equilibrium between the neutral and ionic form of the fluorinated phenols and the charge onto the liposomal surface determined by Zeta Potential measurements in a wide pH range [4]. [1] Mihajlovic, M., Lazaridis, T. J. Phys. Chem. 2006, 110, 3375-3384. [2] Hanakam, F., Gerish, G., Lotz, S., Alt, T., Seeling, A. Biochemistry 1996, 35, 11036-11044. [3] De Alba, E. Weiler, S., Tjandra, N. Biochemistry 2003, 42, 14729-14740. [4] Gasbarri, C., Angelini, G. submitted.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11564/526109
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