title: Delivery of fluorophores by calcium phosphate-coated nanoliposomes and interaction with Staphylococcus aureus biofilms.
abstract: The delivery capacity and mechanical stability of calcium phosphate (CaP) coated 1,2-dioleoyl-sn-glycero-3-phosphate (DOPA) liposomes free and adsorbed on bacterial surface was investigated introducing either acridine orange (AO) or 5,10,15,20-Tetrakis(1-methyl-4-pyridinio)porphyrin (TMP) in the aqueous core of the liposomes. The obtained nanomaterials were thoroughly characterized by electron and optical microscopy and by fluorescence techniques. Distribution of the AO and TMP molecules between the aqueous liposomes core and the outer solution was demonstrated by the band shifts and broadening of the excitation-emission matrices and the modified Stern-Volmer model for fluorescence quenching. In aqueous suspensions, c.a. 40% of AO was released to the outer solution while only a small percentage of TMP was observed to reach the outer liposome surface. The nanoliposomes adhesion capacity and the leaking of fluorophore molecules to Staphylococcus aureus (S. aureus) biofilms were further evaluated. A close interaction between liposomes and S. aureus biofilm was evidenced by TEM and SEM imaging. Epifluorescence experiments demonstrated that CaP-coated liposomes have good biofilm staining capability after two hours incubation of the biofilms with the liposomes, thus supporting an important release of the fluorophores when in contact with the biofilm. Altogether, the obtained results strongly suggest that CaP-coated liposomes are capable of activating drug release when in presence of S. aureus biofilms and smears. The studies herein presented, indicate that CaP-coated liposomes are potential vehicles for the selective delivery of drugs to S. aureus biofilms, as is the case of the singlet oxygen photosensitizer TMP, a well known photodynamic antibacterial agent.
authors.affiliation: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4, 1900 La Plata Argentina.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Rivero Berti
authors.affiliation: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4, 1900 La Plata Argentina. Electronic address: mlaura@inifta.unlp.edu.ar.
authors.forename: María Laura
authors.initials: ML
authors.lastname: Dell' Arciprete
authors.affiliation: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4, 1900 La Plata Argentina.
authors.forename: María Laura
authors.initials: ML
authors.lastname: Dittler
authors.affiliation: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4, 1900 La Plata Argentina.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Miñan
authors.affiliation: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4, 1900 La Plata Argentina.
authors.forename: Mónica
authors.initials: M
authors.lastname: Fernández Lorenzo de Mele
authors.affiliation: Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, Casilla de Correo 16, Sucursal 4, 1900 La Plata Argentina.
authors.forename: Mónica
authors.initials: M
authors.lastname: Gonzalez
mesh_terms: D000165:Acridine Orange / Q000737:chemistry; D000327:Adsorption; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D002130:Calcium Phosphates / Q000737:chemistry*; D004339:Drug Compounding; D065546:Drug Liberation; D005456:Fluorescent Dyes / Q000737:chemistry; D007700:Kinetics; D008081:Liposomes / Q000737:chemistry* / Q000494:pharmacology; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures / Q000737:chemistry*; D010712:Phosphatidic Acids / Q000737:chemistry; D011166:Porphyrins / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000502:physiology; D013535:Suspensions; D014867:Water / Q000737:chemistry
chemical_list: D002130:Calcium Phosphates; D005456:Fluorescent Dyes; D008081:Liposomes; D010712:Phosphatidic Acids; D011166:Porphyrins; D013535:Suspensions; C092399:meso-tetrakis(1-methyl-4-pyridiniumyl)porphyrin; D014867:Water; C037657:dioleoylphosphatidic acid; C020243:calcium phosphate; D000165:Acridine Orange
keywords: 5, 10, 15, 20-Tetrakis(1-methyl-4-pyridinio)porphyrin; Acridine orange; Calcium phosphate; Nanoliposomes; Staphylococcus aureus