Water-containing nanocapsules preparation

Nanoparticles/Nanocapsules Obtained by Inter facial Polymerization Nanoparticles/ nanocapsules can be obtained by fast polymerization of a monomer at the interface between the organic and the aqueous phase of an emulsion. Alkylcyanoacrylates have been proposed for the preparation of both oil- and water-containing nanocapsules [59], These monomers polymerize within a few seconds, initiated by hydroxyl ions from equilibrium dissociation of water or by nucleophilic groups of any compound of the polymerization medium. 

This method, also known as the nanoprecipitation method, can be applied to numerous synthetic poly-mers. ° In general, the polymer is dissolved in acetone and the polymer solution is added into water. The acetone is then evaporated to complete the formation of the particles. Surface active agents are usually added to water to ensure the stability of the polymer particles. This easy technique of nanoparticle preparation was scaled up for large batch production. It leads to the formation of nanospheres. Nanocapsules can easily be prepared by the same method just by adding a small amount of an organic oil in the polymer solution.When the polymer solution is poured into the water phase, the oil is dispersed as tiny droplets in the solvent-non-solvent mixture and the polymer precipitates on the oil droplet surface. This method leads to the preparation of oil-containing nanocapsules... 

In pharmaceutical preparations, soybean oil emulsions are primarily used as a fat source in total parenteral nutrition (TPN) regimens. Although other oils, such as peanut oil, have been used for this purpose, soybean oil is now preferred because it is associated with fewer adverse reactions. Emulsions containing soybean oil have also been used as vehicles for the oral and intravenous administration of drugs drug substances that have been incorporated into such emulsions include amphotericin, " diazepam, retinoids, vitamins, poorly water-soluble steroids, fluorocarbons, and insulin. In addition, soybean oil has been used in the formulation of many drug delivery systems such as liposomes, microspheres, dry emulsions, self-emulsifying systems, and nanoemulsions and nanocapsules. ... 

Tiarks et al. have described in detail the theory of droplets composed of binary mixtures in relation to the preparation of polymeric nanocapsules containing HD by miniemulsion polymerization using poly(methyl methacrylate) (PMMA) or PS polymer [37]. First, a miniemulsion of oil phase (monomer -r HD -t initiator) dispersed in aqueous phase and containing an appropriate surfactant is prepared by ultrasonication. The polymerization is initiated by heating the emulsion to 68 °C. When the polymer is formed it separates from the HD phase and, depending on the interfadal tension and spreading coeffidents of monomer/polymer, HD (hydrophobe) and water, capsules with different morphologies are obtained. 

The method for preparing biodegradable poly(alkylcyanoacr 4ate) nanospheres has provided the basis for the development of polycyanoacrylate nanocapsules. Al Khouri-Fallouh et al (1986) proposed an original method in which the monomer is solubilized in an alcohol phase containing an oil and is then dispersed in an aqueous phase containing surfactants. In contact with water, the alcohol phase diffuses and favours the formation of aver fine oil-in-water emulsion. The monomer, insoluble in water, polymerizes at the interface of the phases to form the wall of the nanocapsules. 

The preparation of nanoparticles by precipitation from an organic solution is well known from the preparation of polymeric nanocapsules and can also be used for the SLN production. The lipid, drug and the stabilizer(s) are dissolved in a water-miscible organic solvent (e.g. acetone, ethanol) or solvent mixture and this solution is dropped in the stirred aqueous phase that may contain a hydrophilic surfactant. Chen et al. firstly evaporated a part of the solvent mixture at elevated temperature before injection into the cooled aqueous phase under stirring. ... 

Utama et al. [46] recently proposed an alternative strategy for the preparation of nanocapsules using RAET polymerization in an inverse miniemulsion system. In this approach, dispersed aqueous droplets (with RAET-based active stabilizers at their interface) simply acted as templates, and chain extension (with hydrophobic monomers and crosslinkers contained in the surrounding continuous phase) yielded the nanocapsules. More specifically, methyl methacrylate (MMA) [46] or styrene [47], crosslinker (EGDMA or DVB, respectively), and initiator (AIBN) were dissolved in a toluene continuous phase. Water droplets containing sodium chloride as lipophobe were formed in these toluene solutions and stabilized with RAET-synthesized poly[M-2-(hydroxypropyl methacrylamide)]-h/oc -poly(methyl methacrylate) (PHPMA-h-PMMA) or PHPMA-h-PS block copolymers, where the PHPMA segment is hydrophilic. The subsequent polymerization was confined to... 

Nanocapsules act like a reservoir, which are called vesicular systems. They carry the active substance entrapped in the solid polymeric membrane or on their surfaces. The cavily inside contains either oil or water. A schematic diagram of Polymer Nanocapsules is shown in Fig. 9.2 [5], There are different methods that are used nowadays to prepare polymeric nanoparticles, such as nanoprecipitation (also termed as the solvent diffusion and solvent displacement method), solvent evaporation, dialysis, microemulsion, surfactant-free emulsion, salling-out, supercritical fluid technology, and interfacial polymerization [2]. Among these methods, nanoprecipitation is a fast and simple process, which does not require a pre-prepared polymer emulsion before the nanoparticle preparation. It produces a dispersion of nanoparticles by precipitation of preformed hydrophobic polymer solution. Under... 

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