title: Giant liposome microreactors for controlled production of calcium phosphate crystals.
abstract: Calcium phosphates are among the most important biominerals in living organisms, where they play both a mechanical and a calcium storage role. Their growth in vivo is under strong biological control, and this process occurs in closed spaces. Our aim in this paper is to describe a microreactor system able to control the mineralization process within closed spaces. To this aim we produce giant liposomes containing calcium ions as active ions in the mineralization process, spermine as an activator of crystal growth, and alkaline phosphatase as a catalyst to convert phosphate esters into phosphates. These phosphate esters are provided in the form of p-nitrophenyl phosphate outside of the liposomes. It is demonstrated that these amphiphilic molecules are able to diffuse through the lipidic container and to be subsequently hydrolyzed under enzymatic catalysis into active phosphate species which interact with the already available calcium and spermine to produce calcium phosphates only in the interior of the liposomes. This opens the route to control the calcium phosphate particle size in biomimetic systems.
authors.affiliation: Institut Charles Sadron, Unité Propre 22, CNRS, 6 Rue Boussingault, 67083 Strasbourg Cedex, France.
authors.forename: Marc
authors.initials: M
authors.lastname: Michel
authors.forename: Mathias
authors.initials: M
authors.lastname: Winterhalter
authors.forename: Laurent
authors.initials: L
authors.lastname: Darbois
authors.forename: Joseph
authors.initials: J
authors.lastname: Hemmerle
authors.forename: Jean Claude
authors.initials: JC
authors.lastname: Voegel
authors.forename: Pierre
authors.initials: P
authors.lastname: Schaaf
authors.forename: Vincent
authors.initials: V
authors.lastname: Ball
mesh_terms: D000469:Alkaline Phosphatase / Q000737:chemistry*; D002130:Calcium Phosphates / Q000138:chemical synthesis*; D002384:Catalysis; D004952:Esters / Q000737:chemistry; D008081:Liposomes / Q000737:chemistry*; D046210:Microfluidic Analytical Techniques; D010316:Particle Size; D013499:Surface Properties; D013997:Time Factors
chemical_list: D002130:Calcium Phosphates; D004952:Esters; D008081:Liposomes; D000469:Alkaline Phosphatase