Polymer micelles dissolution

Several methods for effective solubilization of drugs into polymer micelles have been developed (Fig. 2). The dialysis method (Fig. 2A) is most widely used for many polymeric micelle systems. The first step involves the dissolution of both polymer and drug in a water-miscible organic solvent such as acetonitrile, acetone, dimethylformamide, or ethanol. Then, the polymer-drug solution is dialyzed against water. As the organic... 

Micelle solutions of PlPAAm-Ci8H35 was prepared by direct dissolution of the polymer in cold water (4°C) due to its good water solubility [23]. Each solution of PIPAAm-PSt, PlPAAm-PBMA, and PIPAAm-PLA was prepared by dissolving each copolymer in DMF, A-ethylacetamide, and DMAc, respectively. The solutions were put into a dialysis bag (MWCO = 13,000) and dialyzed against distilled water at 10°C, 20°C, and 4°C, respectively, for 24 hours. The micelles were purified with ultrafiltration membrane of 200,000 molecular weight cut off at 4°C. The aqueous solution was lyophilized to leave a white powder of micelles. 

In spatially evolving multiphase media (e.g., during dissolution of a porous medium, or phase separation in a polymer blend), the mean curvature of the interface between two phases is of interest. Curvature is a sensitive indicator of morphological transitions such as the transition from spherical to rod-like micelles in an emulsion, or the degree of sintering in a porous ceramic material. Furthermore, important physicochemical parameters such as capillary pressure (from the Young-Laplace equation) are curvature-dependent. The local value of the mean curvature K — (1 /R + 1 /Ri) of an interface of phase i with principal radii of curvature Rx and R2 can be calculated as the divergence of the interface normal vector ,... 

The solid dispersion method (Fig. 2B) was used for solubilization of paclitaxel into PEG-poly(D,L-lactide) diblock copolymer micelles. Paclitaxel and the polymer were dissolved in acetonitrile followed by evaporation of the solvent under a stream of nitrogen at 60°C to obtain a gel-like polymer-drug matrix. Dissolution of the solid matrix in water at about 60° C with stirring led to formation of drug-loaded micelles. Because a heating is needed to completely dissolve the polymer-drug matrix, this method may not be not desirable for thermally unstable drugs. 

Fullerenes and their derivatives are of broad interest in various fields ranging from ferromagnetism [87] over their application as possible HIV inhibitors [88] to tumor-therapeutic active substance in biological systems [89]. Although C6o is insoluble in water, dissolution may be accomplished by using water-soluble polymers [90] or surfactant solutions containing amphiphilic block-copolymers [91], micelles or liposomes [92, 93]. The immobilization of... 

Further progress is expected in the development of novel methods for the preparation of polymer-immobilized clusters and nanoparticles. A promising direct synthesis of these products is the dissolution of zero-valent metals into polymer solutions that function as macroligands. Subsequent recrystallization of particles then occurs, much like what occurs in biological systems (Section XI). Stabilization of nanoparticles and clusters during polymerization of micelle-forming monomers could become a significant practical method. 

A well-known feature of surfactant solutions is their ability to dissolve a variety of oil-soluble materials, e.g., hydrocarbons, esters, perfumes, dyes, and so on. This property is utilized in the compounding of many formulations, the process involving the dissolution of the solubihzate in the surfactant micelles. Formation of polymer/surfactant complexes is currently regarded as a depression of the critical aggregation concentration of the surfactant. According to this picture, superior solubilization in such systems can be anticipated... 

In the direct dissolution method, the amphiphilic polymer is dissolved in an aqueous solvent, which leads to micelliza-tion. This technique, used mainly for moderately hydrophobic polymers, such as PEG-PPO (poly(ethylene glycol)), relies on heating and sonication of the solution to promote micellization. While simple, direct dissolution is not generally effective for the preparation of most micelles. Highly hydrophobic polymers cannot be made into micellar structures by this method. In addition, it is difficult to use this method to load hydrophobic drugs into micelles. ... 

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