Nanoparticle injection methods

A similar technique, the so-called spontaneous emulsification solvent diffusion method, is derived from the solvent injection method to prepare liposomes [161]. Kawashima et al. [162] used a mixed-solvent system of methylene chloride and acetone to prepare PLGA nanoparticles. The addition of the water-miscible solvent acetone results in nanoparticles in the submicrometer range this is not possible with only the water-immiscible organic solvent. The addition of acetone decreases the interfacial tension between the organic and the aqueous phase and, in addition, results in the perturbation of the droplet interface because of the rapid diffusion of acetone into the aqueous phase. 

Recently a mercaptoundecanoicacid (MUA) CdSe nanoparticle film was formed by electrophoretic deposition. In this method a colloidal suspension of TOPO-capped CdSe nanoparticles was prepared by the hot injection method, followed by ligand exchange to produce the MUA-capped CdSe nanoparticles. The as-prepared MUA-capped CdSe nanoparticles were washed with ethyl acetate and ethyl ether, followed by re-suspension in ethanol. CdSe nanoparticle films measuring 2.75 mm in thickness were electrodeposited at an applied voltage of 5V with a deposition time of 5 min. 

The procedure chosen for the preparation of lipid complexes of AmB was nanoprecipitation. This procedure has been developed in our laboratory for a number of years and can be applied to the formulation of a number of different colloidal systems liposomes, microemulsions, polymeric nanoparticles (nanospheres and nanocapsules), complexes, and pure drug particles (14-16). Briefly, the substances of interest are dissolved in a solvent A and this solution is poured into a nonsolvent B of the substance that is miscible with the solvent A. As the solvent diffuses, the dissolved material is stranded as small particles, typically 100 to 400 nm in diameter. The solvent is usually an alcohol, acetone, or tetrahydrofuran and the nonsolvent A is usually water or aqueous buffer, with or without a hydrophilic surfactant to improve colloid stability after formation. Solvent A can be removed by evaporation under vacuum, which can also be used to concentrate the suspension. The concentration of the substance of interest in the organic solvent and the proportions of the two solvents are the main parameters influencing the final size of the particles. For liposomes, this method is similar to the ethanol injection technique proposed by Batzii and Korn in 1973 (17), which is however limited to 40 mM of lipids in ethanol and 10% of ethanol in final aqueous suspension. 

The IBM nanoparticle synthesis route is a combination of the polyol method and the thermolysis routes. The rapid injection of the organometallic precursor into a hot solution containing the polyol stabilizing agents allows for the immediate formation of nuclei. 

Schubert, M.A. and Miiller-Goymann, C.C. (2003) Solvent injection as a new approach for manufacturing hpid nanoparticles—evaluation of the method and process parameters. EJPB. 55(1), 125. 

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