Nasal vaccination with poly(ß-amino ester)-poly(d,l-lactide-co-glycolide) hybrid nanoparticles.

Mucosal vaccination stimulates both mucosal and systemic immunity. However, mucosal applications of vaccine antigens in their free form generally result in poor systemic immune responses and need adjuvantation. In this study, bovine serum albumin loaded, new hybridised poly(ß-amino ester)-poly(d,l-lactide-co-glycolide) nanoparticles were prepared by double emulsion-solvent evaporation method, characterised and evaluated in vivo as nasal vaccine carriers. Cationic spherical particles with a mean size of 240nm, good physical stability and high encapsulation efficiency were obtained. Protein structure was not affected throughout preparation and minimal toxicity was shown in Calu-3 and A549 cells. Nasal vaccination with these nanoparticles revealed markedly higher humoral immune responses compared with free antigen following intranasal and subcutaneous immunisation. Mucosal immune response was also stimulated and cytokine titres indicated that Th1 and Th2 pathways were successfully activated. This study shows that the formulated hybrid nanoparticles can be a promising carrier for nasal immunisation of poor antigenic proteins.

Evaluation of different buffers on plasmid DNA encapsulation into PLGA microparticles.

Double emulsion solvent evaporation is a widely used method to prepare poly(dl-lactide-co-glycolide) (PLGA) microparticles encapsulating plasmid DNA. There are inherent problems associated with preparing plasmid DNA in this form, in particular the DNA is liable to degrade during manufacture and the resulting powder has low encapsulation efficiencies. This study compares the use of two buffers, 0.1M NaHCO(3) and 0.07M Na(2)HPO(4) and the effect these have on the encapsulation efficiency and other critical parameters associated with these encapsulated DNA materials. Both buffers preserved the conformation of the original plasmid DNA during the homogenization process, but those made with 0.07M Na(2)HPO(4) had higher encapsulation efficiencies, as well as smaller diameters, compared with those made with 0.1M NaHCO(3) (encapsulation efficiencies of 40.72-45.65%, and mean volume diameters of 2.96-4.45microm). Buffers with a range of pH from 5 to 12 were investigated, and it was demonstrated that pH 9 was the point at which the highest amount of supercoiled DNA was balanced with the highest encapsulation efficiency. To simulate in vitro release, it was shown that microparticles made with 0.07M Na(2)HPO(4) had lower DNA release rates than those made with 0.1M NaHCO(3). These results demonstrate that the use of different buffers can aid in retaining the conformation of plasmid DNA, and can also modulate the amount of DNA encapsulated and the release profiles of microparticles.

Effect of preparative variables on small interfering RNA loaded Poly(D,L-lactide-co-glycolide)-chitosan submicron particles prepared by emulsification diffusion method.

In this study, poly(D,L-lactide-co-glycolide) (PLGA)-chitosan particles were investigated as an effective delivery system for small interfering RNA (siRNA) by emulsification diffusion method. The type, molecular weight and concentration of chitosan, PLGA type as well as centrifugation and freeze-drying process were amongst the investigated variables. PLGA-chitosan particles obtained were positively charged with particle size between approximately 0.4-1 microm depending on type, molecular weight and concentration of chitosan as well as type of PLGA. A better siRNA loading capacity was observed when a higher degree of 'uncapped end groups' were used. The addition of trehalose has also been shown to stabilize these particles from severe aggregation induced by freeze-drying. It was found that physical properties of PLGA-chitosan particles and their siRNA binding capacity were highly influenced by certain preparation parameters. The desired positive charge of submicron size range PLGA-chitosan particles could therefore be obtained by adjusting and optimizing these preparative and formulation parameters.

Particulate delivery systems for biodefense subunit vaccines.

Expanding identification of potentially protective subunit antigens and correlates of protection has provided a basis for the introduction of safer vaccines. Despite encouraging results in animal models, the significant potential of particulate delivery systems in vaccine design has not yet translated into effective vaccines available for use in humans. This review article will focus on the current status of the development of particulate vaccines, mainly liposomes and bio-degradable polymers, against potential agents for biowarfare: plague, anthrax, botulinum, and smallpox; and filoviruses: Marburg and Ebola.