Emulsion-evaporation method

Figure 6. Preparation scheme for the emulsion-evaporation method.

A) Elaboration of PLLA-based superparamagnetic nanoparticles Characterization, magnetic behavior study and in vitro relaxivity evaluation Abstract. Oleic acid-coated magnetite has been encapsulated in biocompatible magnetic nanoparticles (MNP) by a simple emulsion evaporation method. 

In recent years, the crystal and particle engineering of pharmaceutical materials and drug delivery systems with SCF technology has gained momentum due to the limitations of conventional methodst l. This technology offers the advantage of being a one-step process, and appears to be superior to other conventional incorporation methods such as emulsion evaporation methods " ]. 

Figure 12.3 Synthesis of biodegradable nanopaiticles (NPs) via nanopiedpitation and emulsion-evaporation methods [7],...

Chloropromazine (8—34 wt% loading) has been microencapsulated in PCL-cellulose propionate blends by the emulsion solvent evaporation method (61). Phase separation for some ratios of the two polymers was detectable by SEM. The release rate from microcapsules in the size range of 180-250 pm in vitro (Fig. 11) was directly proportional to the PCL content of the blend, the half-life (50% drug release)... 

In an effort to develop an effective bioadhesive system for buccal administration, insulin was encapsulated into polyacrylamide nanoparticles by the emulsion solvent evaporation method [98]. Though nanoparticle formation ensures even distribution of the drug, pelleting of the nanoparticles was performed to obtain three-dimensional structural conformity. In addition, it was hypothetized that the pelletized particles will remain adhered to the mucosa, leading to good absorption. While studying bioadhesion and drug release profiles, it was found that the... 

The most widely used emulsion solvent evaporation method for preparation of nanoparticles using PLGA requires surfactants to stabilize the dispersed particle [23]. This method often has a problem that the surfactant remains at the surface of the particles and is then difficult to remove when PVA is used as surfactant. Other surfactants such as the span series or tween series, PEO, etc. are also used... 

In the other procedure, Rojas et al. [215] optimized the encapsulation of BLG within PLGA microparticles prepared by the multiple emulsion solvent evaporation method. The role of the pH of the external phase and the introduction of the surfactant tween 20, in the modulation of the entrapment and release of BLG from microparticles were studied. Better encapsulation of BLG was noticed on decreasing the pH of the external phase. Addition of tween 20 increased the encapsulation efficiency of BLG and considerably reduced the burst release effect. 

Poly(alkyl-cyanoacrylates) As poly(alkyl-cyanoacrylates) form strong bonds with polar substrates including the skin and living tissues, they exhibit bioadhesive properties. These polymers are synthesized by free-radical, anionic, or zwitterionic polymerization. As detailed in a recent review, poly(alkyl-cyanoacrylate) nanoparticles are prepared by emulsion polymerization, interfacial polymerization, nanoprecipitation, and emulsion-solvent evaporation methods [102],... 

Lemos-Senna, E., Wouessidjewe, D., Lesieur, S., and Duchene, D. (1998), Preparation of amphiphilic cyclodextrin nanospheres using the emulsion solvent evaporation method, influence of the surfactant on preparation and hydrophobic drug loading, Int. J. Pharm., 170,119-128. 

The solvent emulsification/evaporation method involves lipid precipitation in O/W emulsions. Solid lipids are dissolved in a water-immiscible organic solvent (e.g., cyclohexane) followed by emulsification in an aqueous medium. Upon evaporation of the solvent, the nanoparticle dispersion is formed due to lipid precipitation. Residue of organic solvents is the major problem of this method [94], However, the microemulsion and solvent emulsification/evaporation methods can be performed conveniently in the laboratory without specific apparatuses. 

Liu, R., Ma, G.H., Meng, F.-T., and Su, Z.-G., Preparation of uniform-sized PLA microcapsules by combining Shirasu Porous Glass membrane emulsification technique and multiple emulsion-solvent evaporation method, J. Contrail. Ret, 103, 31, 2005. 

Herrmann, J. Bodmeier, R. Somatostatin containing biodegradable microspheres prepared by a modified solvent evaporation method based on W/O/W-multiple emulsions. Int. J. Pharm. 1995, 126 (1-2), 129-138. 

Yang, Y.-Y. Chia, H.-H. Chung, T.-S. Effect of preparation temperature on the characteristics and release profiles of PLGA microspheres containing protein fabricated by double-emulsion solvent extraction/evaporation method. J. Controlled Release 2000, 69 (1), 81-96. 

Precipitation is a variation on the evaporation method. The emulsion consists of polar droplets dispersed in a non-polar medium.Solvent may be removed from the droplets by the use of a cosolvent. The resulting increase in the polymer drug concentration causes precipitation forming a suspension of microspheres. 

The solvent diffusion/spontaneous emulsification process can create much smaller droplet sizes than the solvent evaporation method. In this case, the dispersed phase is composed of a water-immiscible solvent and a water-miscible solvent, which is emulsified into an aqueous solution. The diffusion of the water-miscible solvent causes turbulence and further breakup of the droplets in the emulsion. The removal of solvent can be conducted similarly to the solvent evaporation method. 

A technique based on the formation of a multiple emulsion with an external aqueous phase was developed for the encapsulation of water-soluble drugs in order to replace the external oil phase. Possible unwanted interactions between the oil and the emulsified wax such as swelling or dissolution of the wax, clean-up requirements of the final product, and recovery of the oil phase could be eliminated. In analogy to the encapsulation of water-soluble drugs within polymeric microparticles by a w/o/w-solvent evaporation method, a molten wax phase was used instead of an organic polmer solution. A heated aqueous solution of pseudoephedrine HCl was emulsified into the molten carnauba wax, followed by the emulsification of this w/o-emulsion into a heated external aqueous phase. The temperature of the internal and external aqueous phases had to be kept above the melting temperature of the wax in order to avoid premature... 

Emulsions of water and CO2 have been used to form liposomes in one step without any organic solvent (57). The liposomes were made by forming a W/C emulsion stabilized with/L-i -dipalmitoylphosphatidylcholine. The pressure was reduced to form the liposomes by a reversed phase evaporation method. Large unilamellar liposomes with diameters of 0.1 to 1.2 pm were formed and used to trap D-( + )-glucose. 

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