title: Physicochemical characterization and study of in vitro interactions of pH-sensitive liposomes with the complement system.
abstract: Complement activation is an important step in the acceleration of liposome clearance. The anaphylatoxins released following complement activation may motivate a wide variety of physiologic changes. We performed physicochemical characterization and in vitro studies of the interaction of complement system with both noncirculating and long-circulating pH-sensitive and nonpH-sensitive liposomes. The liposomes were characterized by diameter, zeta potential, and atomic force microscopy (AFM). The study of liposome interactions with complement system was conducted using hemolytic assay in rat serum. All liposomes presented a similar mean diameter (between 99.8 and 124.3 nm). The zeta potential was negative in all liposome preparations, except in liposomes modified with aminopoly (ethyleneglycol) 2000-distearoylphosphatidylethanolamine (aPEG(2000)-DSPE), which presented positive zeta potential. Atomic force microscopy images showed that non-long-circulating pH-sensitive liposomes are prone to vesicles aggregation. Non-pH-sensitive liposomes complement system activates, while pH-sensitive liposomes showed to be poor complement activators in rat serum.
authors.affiliation: Faculdade de Farmácia, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Vildete A S
authors.initials: VA
authors.lastname: Carmo
authors.forename: Mônica C
authors.initials: MC
authors.lastname: De Oliveira
authors.forename: Eduardo C O
authors.initials: EC
authors.lastname: Reis
authors.forename: Tânia M P D
authors.initials: TM
authors.lastname: Guimarães
authors.forename: José M C
authors.initials: JM
authors.lastname: Vilela
authors.forename: Margareth S
authors.initials: MS
authors.lastname: Andrade
authors.forename: Marilene S M
authors.initials: MS
authors.lastname: Michalick
authors.forename: Valbert N
authors.initials: VN
authors.lastname: Cardoso
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000737:chemistry; D003167:Complement Activation; D003169:Complement Inactivator Proteins / Q000737:chemistry; D003165:Complement System Proteins / Q000737:chemistry*; D016503:Drug Delivery Systems; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008055:Lipids / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D008297:Male; D008566:Membranes / Q000737:chemistry; D018625:Microscopy, Atomic Force; D010713:Phosphatidylcholines / Q000737:chemistry; D051381:Rats; D017208:Rats, Wistar
chemical_list: D003169:Complement Inactivator Proteins; D008055:Lipids; D008081:Liposomes; D010713:Phosphatidylcholines; D003165:Complement System Proteins; D002784:Cholesterol; C017251:1,2-oleoylphosphatidylcholine