Encapsulation efficiency

The interfacial cross-linking polymerization has been demonstrated to be a suitable method for the production of xylan microcapsules with high drug encapsulation efficiency. SD-... 

Y. (2010). Microencapsulation techniques, factors influencing encapsulation efficiency. Journal of Microencapsulation, Vol. 27, 3, (June 2010), pp. (187-197), ISSN... 

Saxena A., Sachin K, Bohidar H.B., Verma A.K. 2005. Effect of molecular weight heterogeneity on drug encapsulation efficiency of gelatin nano-particles. Colloids and Surfaces B Biointerfaces 45,42-48. 

Reverse Phase Evaporation Szoka and Papahadjopoulos (1978) developed the so-called reverse phase evaporation method. Vesicles prepared with this technique (REV) show higher encapsulation efficiencies of hydrophilic compounds than unextruded MLV. 

Multivesicular Liposomes Kim and his colleages described a method for the preparation of cell size liposomes with high encapsulation efficiency the so-called multivesicular liposomes (Kim et al., 1983). The lipid phase consists of a combination of amphiphatic lipids and a small amount of triglycerides (triolein or trioctanoin) dissolved in chloroform-diethyl ether (1 1). The aqueous phase is slowly added to the organic phase and after vigorous shaking a water-ip-lipid emulsion is formed (Fig. 2A-B). Via a narrow Pasteur pipet the emulsion is subsequently added to a sucrose solution. 

A disadvantage of the ethanol injection method to produce SUV is the need to use a low lipid concentration, resulting in a low encapsulation efficiency of the aqueous phase. The dispersions can be concentrated by ultracentrifugation, ultrafiltration, or removal of water by evaporation. 

Upon the spontaneous rearrangement of anhydrous phospholipids in the presence of water into a hydrated bilayer structure, a portion of the aqueous phase is entrapped within a continuous, closed bilayer structure. By this process water-soluble compounds are passively entrapped in liposomes. The efficiency of encapsulation varies and depends, for example, on the method of preparation of liposomes and the phospholipid concentration during preparation. Different parameters can be used to describe the encapsulation efficiency ... 

Reproducibility of the production process in terms of, e.g., size distribution, encapsulation efficiency, and release pattern Absence of unwanted side products (e.g., residues of organic solvents in the bilayer)... 

Kirby, C. J., and Gregoriadis, G. (1984). A simple procedure for preparing liposomes capable of high encapsulation efficiency under mild conditions, in Liposome Technology, Vol. 1 (G. Gregoriadis, ed.), CRC Press, Boca Raton, pp. 19-27. 

REVs Reverse-phase evaporation vesicles LUVs prepared by reverse-phase evaporation method, high encapsulation efficiency 11,12... 

FTVs Freeze-thaw vesicles LUVs prepared by freeze-thaw method, high encapsulation efficiency ... 

Nicholas AR, Scott MJ, Kennedy Nl, et al. Effect of grafted polyethylene glycol (PEG) on the size, encapsulation efficiency and permeability of vesicles. Bio-chim Biophys Acta 2000 1463 167. 

Encapsulation efficiencies are listed as a function of ethanol concentration for distearoyl-phosphatidyl-choline/choles-terol/l,2-dioleoyl-3-dimethylammoniumpropane large unilamellar vesicle (LUVs). The initial oligonucleotide-to-lipid ratio was 0.034 mol/mol (0.3mg/mg). The LUVs used for these experiments were 99 22 nm in size. The encapsulation values are given as mean SD. 

Micropsheres were successfully prepared using the PLGA-lysozyme conjugate by a single emulsion method. Encapsulation efficiency of lysozyme... 

For water-soluble agents, the encapsulation efficiency and thus the internal volume of vesicles which determines the amount of encapsulated material, is a very important factor with regard to the in vitro efficacy. It depends on the liposome size, lipid composition and lamellarity. When the number of liposomes delivered has to be known, the enumeration of the suspension can be performed by multinuclear NMR and photon correlation spectroscopy (110)-... 

Important criteria for the evaluation of liposomal quality are drug-to-lipid ratio, encapsulation efficiency, size, and lamellarity. The higher the drug-to-lipid ratio, the higher is the payload of the carrier and the lower the systemic burden... 

In addition to the hydrophobic interaction mentioned above to encapsulate guest molecules, other types of nonspecific interactions have also been explored to enhance binding. For example, block copolymer micelles based on PEO as hydrophilic segments and poly(/3-benzyl L-aspartate) as hydrophobic blocks have used to encapsulate doxombicin. The encapsulation efficiency of doxombicin, an aromatic anticancer drug molecule, has been found to be significantly higher. This observation has been attributed to the tt-tt interaction between the anthracycUne moiety of doxorubicin and the benzyl group of poly(/3-benzyl L-aspartate) (Cammas-Marion et al. 1999). 

---