title: Interaction between Albumin and Pluronic F127 Block Copolymer Revealed by Global and Local Physicochemical Profiling.
abstract: The interaction of human serum albumin (HSA) with amphiphilic block copolymer Pluronic F127 has been investigated by several physical methods. Interest in studying this system stems from a broad range of bioactivities involving both macromolecules. Serum albumins constitute a significant class of proteins in the circulatory system, acting as carriers for a wide spectrum of compounds or assemblies. Pluronic block copolymers have revealed their capacity to ferry a variety of biologically active compounds. Circular dichroism, rheological measurements, and differential scanning microcalorimetry (μDSC) were employed to get insight into the interaction betweeen the two macromolecules. The results reveal that Pluronic F127 induces conformational changes to albumin if it is organized in a micellar form, while albumin influences the self-assembly of Pluronic F127 into micelles or gels. F127 micelles, however, induce smaller conformational changes compared to ionic surfactants. The μDSC thermograms obtained for HSA and/or F127 show that HSA shifts the critical micellar temperature (cmt) to lower values, while concurrently the HSA denaturation behavior is influenced by F127, depending on its concentration. Rheological measurements on solutions of F127 17% have shown that a sol-to-gel transition occurs at higher temperatures in the presence of HSA and the resulting gel is weaker. The global profile on HSA/F127 systems was complemented by local information provided by EPR measurements. A series of X-band EPR experiments was performed with spin probes 4-(N,N'-dimethyl-N-hexadecyl)ammonium-2,2',6,6'-tetramethylpiperidine-1-oxyl iodide (CAT16) and 5-doxyl stearic acid (5-DSA). These spin probes bind to albumin sites and are sensitive to phase transformations in Pluronic block copolymer solutions. For a given F127 concentration, the spin probe binds only to HSA below cmt and migrates to the F127 micelles above cmt. The collective data suggest soft interactions between the macromolecules, with the emerging results projecting potential applications linked to reaching optimal conditions for certain drug formulations.
authors.affiliation: "Ilie Murgulescu" Institute of Physical Chemistry of the Romanian Academy , 202 Splaiul Independentei, Bucharest 060021, Romania.
authors.forename: Maria Victoria
authors.initials: MV
authors.lastname: Neacsu
authors.affiliation: "Ilie Murgulescu" Institute of Physical Chemistry of the Romanian Academy , 202 Splaiul Independentei, Bucharest 060021, Romania.
authors.forename: Iulia
authors.initials: I
authors.lastname: Matei
authors.affiliation: "Ilie Murgulescu" Institute of Physical Chemistry of the Romanian Academy , 202 Splaiul Independentei, Bucharest 060021, Romania.|Department of Physical Chemistry, Faculty of Chemistry, University of Bucharest , Bd. Regina Elisabeta 4-12, Bucharest 030018, Romania.
authors.forename: Marin
authors.initials: M
authors.lastname: Micutz
authors.affiliation: Department of Physical Chemistry, Faculty of Chemistry, University of Bucharest , Bd. Regina Elisabeta 4-12, Bucharest 030018, Romania.
authors.forename: Teodora
authors.initials: T
authors.lastname: Staicu
authors.affiliation: "Ilie Murgulescu" Institute of Physical Chemistry of the Romanian Academy , 202 Splaiul Independentei, Bucharest 060021, Romania.
authors.forename: Aurica
authors.initials: A
authors.lastname: Precupas
authors.affiliation: "Ilie Murgulescu" Institute of Physical Chemistry of the Romanian Academy , 202 Splaiul Independentei, Bucharest 060021, Romania.
authors.forename: Vlad Tudor
authors.initials: VT
authors.lastname: Popa
authors.affiliation: Department of Chemical Engineering, Laboratory of Inorganic Chemistry and Chemistry of Advanced Materials, Aristotle University of Thessaloniki , Thessaloniki 54124, Greece.
authors.forename: Athanasios
authors.initials: A
authors.lastname: Salifoglou
authors.affiliation: "Ilie Murgulescu" Institute of Physical Chemistry of the Romanian Academy , 202 Splaiul Independentei, Bucharest 060021, Romania.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Ionita
mesh_terms: D002152:Calorimetry, Differential Scanning; D002942:Circular Dichroism; D004578:Electron Spin Resonance Spectroscopy; D005782:Gels / Q000737:chemistry; D006801:Humans; D008823:Micelles; D020442:Poloxamer / Q000737:chemistry* / Q000378:metabolism; D012212:Rheology; D000075462:Serum Albumin, Human / Q000737:chemistry* / Q000378:metabolism; D013696:Temperature; D013816:Thermodynamics
chemical_list: D005782:Gels; D008823:Micelles; D020442:Poloxamer; D000075462:Serum Albumin, Human