Encapsulation of plasmid DNA in PLGA-stearylamine microspheres: a comparison of solvent evaporation and spray-drying methods

Abstract

Stearylamine, a positively charged hydrophobic molecule, was tested as a formulation agent for the encapsulation of a model plasmid in PLGA microspheres. The primary objective was to compare the spray-drying and double emulsion solvent evaporation methods and evaluate their suitability for fabricating PLGA-stearylamine plasmid-entrapped microspheres. A luciferase reporter gene plasmid (pGL3-Con) was formulated into microspheres using a 64 kDa PLGA 50:50 polymer blended with stearylamine (SA) at a range of concentrations up to 15%m/m, by the solvent evaporation and spray-drying methods. The microspheres were characterized regarding their size distributions, zeta potentials and morphology by laser diffraction, electrophoretic mobility and scanning electron microscopy (SEM), respectively. Formulated plasmid extracts were assessed for physical damage by agarose gel electrophoresis, and the in vitro biological activity was determined by transfection of a human embryo kidney epithelial (293) cell line. Size distribution analysis showed that SA reduced the median diameters of spray-dried particles from 8.32 to 3.64 microns, with a corresponding reduction in the spread of the distribution, but solvent evaporation microspheres showed an increased median diameter on addition of SA. Concentrations of SA above 10%(m)/(m) resulted in disruption of the smooth morphology of the solvent evaporation particles. There was a SA concentration-dependent tendency in the increase of surface positive charge and resistance to serum nuclease assault and in vitro expression of luciferase protein. These results show that SA and possibly other charged hydrophobic molecules may be useful agents in the formulation of particulate DNA vaccines by both methods.

Agglomerates Containing Pantoprazole Microparticles: Modulating the Drug Release

“…In addition, the particle sizes were not influenced by the lecithin concentration, and all the three spray-dried mannitol/lecithin powders had mean diameters of 3.7 µm, evidently smaller than the size of the pantoprazole-loaded microparticles (mean particle size of 22.0±1.2 µm). The spray-dried mannitol/ lecithin powders had mean diameters compatible to those described in the literature for powders prepared using the same type of equipment (11,39), in which a model plasmid was encapsulated in PLGA/stearylamine microparticles by spray drying (39). The microparticles became more uniform in size and less aggregated and more flowable with the increase of stearylamine.…”

“…The microparticles became more uniform in size and less aggregated and more flowable with the increase of stearylamine. Particle size ranged from 2.1 to 8.3 μm, depending on the stearylamine concentration (39). In another research, DNA microparticles were prepared with polyethylenimine as a complexation agent for DNA (11).…”

Characterization of particles fabricated with poly(D,L-lactic-co-glycolic acid) and an ornithine–histidine peptide as carriers of oligodeoxynucleotide for delivery into primary dendritic cells

“…Li et al have used calcium-phosphate to precipitate plasmid DNA to form PLGA microparticles [15]. Stearylamine [16] and polyethylenimine (PEI) [17] have also been used to encapsulate plasmid DNA into PLGA microparticles. Kasturi et al have shown that plasmid DNA adsorbed on PEI-surface conjugated PLGA microparticles leads to enhanced gene delivery in macrophages [18].…”

Process considerations related to the microencapsulation of plasmid DNA via ultrasonic atomization

“…In addition, bioactivity of biopharmaceutical can be eliminated due to the presence of organic solvents, and the solvents are also difficult to remove completely (Freitas et al, 2005). Spray drying is frequently being employed to prepare microspheres (Atuah et al, 2003;Johansen et al, 2000); but, there are drawbacks to this method that makes it ineffective. These drawbacks include: it is infeasible for temperature sensitive compounds; it has considerable product lost due to inefficient separation in the collecting process (Johansen et al, 2000).…”