Cationic Bilayers on Polymeric Particles:  Effect of Low NaCl Concentration on Surface Coverage

Abstract

The interaction between dioctadecyldimethylammonium bromide (DODAB), chloride (DODAC), or acetate (DODAAc) cationic bilayer fragments (BF) and polystyrene sulfate (PSS) particles (2 × 1011 particles/mL) was evaluated at and above equivalence of total surface areas for bilayers and particles (A b/A p) over a range of low NaCl and lipid concentrations, by means of zeta-potential, ζ, and particle diameter, D z , analysis. In pure water, lipid addition at and above A b/A p = 1 rapidly increased D z and ζ, which reached stable plateau values above those expected at bilayer coverage. By addition of small NaCl concentrations (0.05−5.00 mM), D z decreased with ζ still positive. Therefore, the effect of low salt concentration on the particle coverage with lipid bilayer fragments was surface rearrangement of bilayer fragments on the surface from uneven coverage with some bilayer fragments adsorbed vertically, to perfect bilayer coverage upon addition of small amounts of NaCl. This occurred over a broad range of lipid concentration (0.04−1.0 mM DODA), possibly due to NaCl-induced sealing of adjacent bilayer patches adsorbed on particles. At 0.2 mM lipid, the effect of salt, counterion, and bilayer type (BF or large vesicles, LV) on surface tension at the air−water interface (γ) complemented the evaluation of bilayer behavior at a hydrophobic interface. The γ decay rate and total extent increased with counterion size, NaCl concentration, and frequency of hydrophobic defects in the lipid bilayer. Upon addition of 2 mM NaCl to 0.2 mM DODAB BF or LV, γ decay was much faster for BF, showing the importance of hydrophobic defects in the bilayer to induce its fusion to the air−water interface.

Lipid-based Biomimetics in Drug and Vaccine Delivery

“…Glass microspheres coated with phospholipid layers evaluated the binding specificity of enzymes on cell surface (Obringer et al 1995) or quantified lipid-antibodies binding (Kiser et al, 1998). Recent work continues to investigate lipid-supporting particles based on minerals Nordlund et al 2009;Ahmed & Wunder, 2009;Xu et al, 2009;Oleson & Sahai, 2008;Pyiasena et al, 2008;Senarath-Yapa et al 2007;Moura & Carmona-Ribeiro, 2007;Parida et al, 2006), polymers Jha & Bose, 2009;Thevenot et al, 2008;Bershteyn et al 2008;Zuzzi et al, 2008;Troutier et al, 2005;Pereira et al, 2004), metals eg magnetoliposomes for biomedical applications or contrast agents in magnetic resonance imaging (Bulte & De Cuyper, 2003) or biological cells as templating cores to be dissolved to obtain capsules (Ge et al, 2003) or viruses for enhancing adenovirus tumor targeting in vivo (Singh et al, 2008). Polymer hollow capsules were produced by Möhwald and coworkers (Ge et al, 2003) from the polyelectrolyte layer-by-layer technique on biological cells.…”

“…Silica Carmona-Ribeiro,1997, 2000;Moura and CarmonaRibeiro, 2005, 2006, 2007, latex (Carmona-Ribeiro and Midmore, 1992; or hydrophobic drug particles (Pacheco and Carmona-Ribeiro, 2003;) have been coated with cationic lipids. Optimal cationic bilayer deposition on particles was achieved by coalescence of bilayer fragments at www.intechopen.com adequate experimental conditions for the intervening medium such as pH, ionic strength and concentrations of the interacting components (Moura & Carmona-Ribeiro, 2003;Moura & Carmona-Ribeiro, 2005;Pereira et al, 2004;Pereira et al, 2006). Recently, the optimal bilayer coverage of polystyrene sulfate (PSS) nanoparticles with a cationic dioctadecyldimethylammonium bromide (DODAB) bilayer found an important application adsorbing and successfully presenting antigens to the immune system Lincopan et al, 2009a).…”

“…Electrostatically driven bilayer coverage from bilayer fragments onto oppositely charged latex produced a highly homodisperse particulate for biomolecules adsorption (CarmonaRibeiro and Midmore, 1992;Carmona-Ribeiro, 2003;Pereira et al, 2004;Rosa et al, 2008). Polystyrene sulfate (PSS) particles which are anionic can be covered with single cationic DODAB bilayers forming biomimetic particles prone to be used for DNA, proteins or antigen immobilization .…”

Assembly of horseradish peroxidase within supported cationic bilayers

“…Coating with cationic lipids has been applied to silica, 17 latex, 18 or hydrophobic drug particles. 19 Optimal cationic bilayer deposition on polymeric particles 20 or silicon wafers 21 has been demonstrated to take place with certain compositions of the intervening medium, as determined from experiments involving systematic variation of counter-ion type and concentration and the proportion of surface areas for bilayers and particles or surfaces. Recently, this optimal cationic bilayer coverage on polystyrene sulfate (PSS) nanoparticles allowed successful presentation of protein antigens to the immune system.…”

Partículas e filmes híbridos de polímeros e compostos de amônio quaternário com atividade antimicrobiana

“…Em particular, o DODAB é um lípide catiônico sintético, com grande estabilidade química e propriedades anti-infecciosas bastantes descritas A adesão de vesículas ou a deposição de bicamadas de DODAB ou fosfolipídios sobre superfícies de óxido de silício ou sobre partículas ou filmes poliméricos, na ausência ou presença de polímeros de carga oposta, pode ser uma ferramenta importante para pesquisa e desenvolvimento de biossensores e kits imunológicos (SALAY & CARMONA-RIBEIRO, 1998;SALAY & CARMONA-RIBEIRO, 1999;PEREIRA et al, 2002;PEREIRA et al, 2004 (LU et al, 2005).…”