Physical Adsorption of Bilayer Membranes on Silica

Lipid-based Biomimetics in Drug and Vaccine Delivery

“…The interaction between lipids and particles has been reviewed over the last two decades in a few review articles and book chapters (Carmona-Ribeiro, 1992;Carmona-Ribeiro and Lessa, 1999;Carmona-Ribeiro, 2001 a,b;Carmona-Ribeiro, 2003;Carmona-Ribeiro et al, 2006;Carmona-Ribeiro, 2006;CarmonaRibeiro, 2007;Petri & Carmona-Ribeiro, 2007;Mamizuka & Carmona-Ribeiro, 2007) and lately other excellent reviews appeared in the literature (Bulte & De Cuyper, 2003;Troutier & Ladavière, 2007;Al-Jammal & Kostarelos). Figure 4 illustrated possible assemblies resulting from the interaction between bilayer-forming lipids and particles as depicted from experimental evidences (Carmona-Ribeiro & Midmore, 1992;Carmona-Ribeiro & Herrington, 1993;Rapuano & Carmona-Ribeiro, 1997;Carmona-Ribeiro & Lessa, 1999;Moura & Carmona-Ribeiro, 2003;Moura & Carmona-Ribeiro, 2005;Moura & Carmona-Ribeiro, 2007).…”

“…The main possibilities are: 1) silica particles binding DPPC through hydrogen bonds between Si-OH and O=P-groups; 2) tetraalkylammonium groups at the extracellular region of the erythrocyte membrane forming ion pairs with dissociated silanol on the silica particle and generating hemolytic effects observed for silica. Adsorption isotherms of 4 different bilayers on hydrophilic silica over a range of experimental conditions helped to clarify this issue (Rapuano & Carmona-Ribeiro, 1997). The separate use of synthetic charged membranes with phosphate or tetraalkylammonium groups as polarheads such as are DODAB and DHP bilayer vesicles, to obtain adsorption isotherms on silica established the relative importance of phosphate or tetraalhylammonium on the mechanism of phospholipid deposition onto hydrophilic silica particles.…”

“…The separate use of synthetic charged membranes with phosphate or tetraalkylammonium groups as polarheads such as are DODAB and DHP bilayer vesicles, to obtain adsorption isotherms on silica established the relative importance of phosphate or tetraalhylammonium on the mechanism of phospholipid deposition onto hydrophilic silica particles. Formation of ion pairs between the quaternary ammonium in the choline moiety of the phospholipid and the deprotonated silanol drove vesicle adhesion to the particle but vesicle rupture and bilayer deposition was determined by the cooperative occurrence of several hydrogen bridges between silanol and the phosphate moiety on the phospholipid (Rapuano & Carmona-Ribeiro, 1997). A low affinity between neutral phospholipids and the silica surface and a high affinity for the cationic amphiphile over a range of pH values was obtained (Rapuano & Carmona-Ribeiro, 2000).…”

“…From the comparison between langmuirian adsorption isotherms for PC, DPPC or DODAB deposition on silica particles (50 nm mean diameter), affinity constants for the surface increased in the following order PC<DPPC<DODAB (Rapuano and Carmona-Ribeiro, 1997;Rapuano and Carmona-Ribeiro, 2000). The molecular shape for PC in the bilayer is more cylindrical for PC than for DPPC, the geometric parameter for PC is larger than the geometric parameter for DPPC and it becomes difficult for the PC bilayer to bend and deposit on a curved silica particle but bending is easier for a DPPC bilayer.…”

Interações entre bicamadas lipídicas e interfaces hidrofóbicas

“…[1][2][3][4][5][6][7][8][9] Several surfaces have been used as supports to deposit the bilayer or adhered bilayer vesicles, e.g., glass coverslips for spectroscopic studies, 10 mica sheets for the surface force apparatus, [11][12][13] polymer-coated surfaces with one or more polymer layers, [14][15][16][17][18] bacteria, 19 yeasts 20 or mammalian 21 cell surfaces, mineral particles such as silica, [22][23][24][25][26] glass beads, 27 or titanium dioxide 28 and polymeric particles, such as latex. [29][30][31] The easiest method for preparing high quality phospholipid bilayers on a flat hydrophilic surface is the direct fusion of small unilamellar vesicles, 32,33 a method devised to make unilamellar membranes on glass coverslips for spectroscopic studies.…”