The preparation and characterisation of poly(butyl-2-cyanoacrylate) nanoparticles
Poly (butyl 2-cyanoacrylate) nanoparticles have been prepared with a range of particle sizes by varying the nature and concentration of stabiliser added to the polymerisation medium. Particle size analysis was performed by photon correlation spectroscopy. The range of diameters produced using dextran stabilisers was found to be approximately 100 to 800nm. This could be extended to 3ym using j3 -cyclodextrin and to 20nm using polysorbate 20. The results infer that the nanoparticles are sterically stabilised. The molecular weight of the cyanoacrylate polymer formed during nanoparticle production was found to be dependent on the type of stabiliser used together with the polymerisation pH and monomer concentration. The bulk of the polymer had a relatively low molecular weight (<2000) which indicates that nanoparticles are formed by an aggregative mechanism. Dextran was found to copolymerise with the monomer to give an interfacial layer of the polysaccharide attached by covalent linkages. By using dextrans bearing charged functional groups it was possible to alter the electrophoretic behaviour of the resulting nanoparticles. Partial oxidation of the surface dextran introduced aldehyde groups which were capable of covalently binding a simple amine, aniline, thereby enhancing the uptake and decreasing the release rate of this compound. This technique may be applicable to the covalent coupling of antibodies or cytotoxic agents to the nanoparticle surface. Nanoparticles were radiolabelled with a technetium-99m-dextran complex and the biodistribution of this colloid determined in rabbits by gamma scintigraphy following intravenous injection. Most of the nanoparticle suspension (approximately 50%) was cleared by the liver and spleen. Coating the nanoparticles with non-ionic surfactants (poloxamer 338 or Tetronic 908) failed to alter significantly this distribution pattern.