title: Spectroscopic characterization of 2-amino-N-hexadecyl-benzamide (AHBA), a new fluorescence probe for membranes.
abstract: We report the results of investigation on the spectroscopic properties of a new fluorescent lipophylic probe. The fluorophore o-aminobenzoic acid was covalently bound to the acyl chain hexadecylamine, producing the compound 2-amino-N-hexadecyl-benzamide. The behavior of the probe was dependent on the polarity of the medium: absorption and emission spectral position, quantum yield and lifetime decay indicate distinct behavior in water compared to ethanol and cyclohexane. The probe dissolves in the organic solvents, as indicated by the very low value of steady state fluorescence anisotropy and the short rotational correlation times obtained from fluorescence anisotropy decay measurements. On the other hand, the probe has low solubility in water, leading to the formation of aggregates in aqueous medium. The complex absorption spectrum in water was interpreted as originating from different forms of aggregation, as deduced from the wavelength dependence of anisotropy parameters. The probe interacts with surfactants in pre-micellar and micellar forms, as observed in experiments in the presence of sodium n-dodecylsulphate (SDS), n-cetyltrimethylammonium bromide (CTAB); 3-(dodecyl-dimethylammonium) propane-1-sulphonate (DPS) and 3-(hexadecyl-dimethylammonium) propane-1-sulphonate (HPS), and with vesicles of the phospholipid dimiristoyl-phosphatidylcholine (DMPC). The results demonstrate that AHBA is able to monitor properties like surface electric potential and phase transition of micelles and vesicles.
authors.affiliation: Departamento de Física e Matemática, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes 3900 14040-901 Ribeirão Preto, SP, Brazil.
authors.forename: Cássia Alessandra
authors.initials: CA
authors.lastname: Marquezin
authors.forename: Izaura Yoshico
authors.initials: IY
authors.lastname: Hirata
authors.forename: Luiz
authors.initials: L
authors.lastname: Juliano
authors.forename: Amando Siuiti
authors.initials: AS
authors.lastname: Ito
mesh_terms: D001549:Benzamides / Q000737:chemistry*; D002462:Cell Membrane / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D044367:Phase Transition; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013501:Surface-Active Agents
chemical_list: C516648:2-amino-N-hexadecyl-benzamide; D001549:Benzamides; D005456:Fluorescent Dyes; D012997:Solvents; D013501:Surface-Active Agents