Evaluation of Two Food Grade Proliposomes To Encapsulate an Extract of a Commercial Enzyme Preparation by Microfluidization (original) (raw)
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International journal of pharmaceutics, 2005
The purpose of this study was to systematically investigate the effect of lipid chain length and number of lipid chains present on lipopeptides on their ability to be incorporated within liposomes. The peptide KAVYNFATM was synthesized and conjugated to lipoamino acids having acyl chain lengths of C8, C12 and C16. The C12 construct was also prepared in the monomeric, dimeric and trimeric form. Liposomes were prepared by two techniques: hydration of dried lipid films (Bangham method) and hydration of freeze-dried monophase systems. Encapsulation of lipopeptide within liposomes prepared by hydration of dried lipid films was incomplete in all cases ranging from an entrapment efficiency of 70% for monomeric lipoamino acids at a 5% (w/w) loading to less than 20% for di- and trimeric forms at loadings of 20% (w/w). The incomplete entrapment of lipopeptides within liposomes appeared to be a result of the different solubilities of the lipopeptide and the phospholipids in the solvent used fo...
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There are numerous studies on systems comprising an enzyme encapsulated in unilamellar liposomes and its substrate initially present in the external aqueous media. Most of these studies are focused on enzyme stability and activity in a restricted media. However, the rate of the process is also determined by the capacity of the substrate to permeate towards the liposome inner pool. In spite of this, there are few studies aimed at a quantitative evaluation of the substrate permeation rate and its lifetime inside the liposome pool. In the present work, we describe, in terms of a very simple mechanism, the permeation of glucose and hydrogen peroxide in DPPC unilamellar liposomes. To this aim, we evaluated the rate of the process employing encapsulated glucose oxidase and catalase in the kinetic diffusion controlled limit. Under this condition, the rate of the process becomes zero order in the enzyme and allows a direct evaluation of the rate constant for the permeation process and the lifetime of a substrate molecule incorporated into the liposome inner pool.
International Journal of Pharmaceutics, 2015
A novel "slurry method" was described for the preparation of proliposome powders using soya phosphatidylcholine (SPC) with cholesterol (1:1) and for incorporation of beclometasone dipropionate (BDP) at 2 mole% of the total lipid phase. Proliposomes made with a range of lipid to sucrose carrier ratios were studied in terms of surface morphology using scanning electron microscopy (SEM) and thermal properties using differential scanning calorimetry (DSC). Following hydration of proliposomes, the resultant vesicles were compared to liposomes made using the traditional proliposome method, in terms of vesicle size and drug entrapment efficiency. SEM showed that sucrose was uniformly coated with lipid regardless of lipid to carrier ratio. Liposomes generated using the slurry proliposome method tended to have smaller median size than those generated with the conventional proliposome method, being in the range of 4.72-5.20 mm and 5.89-7.72 mm respectively. Following centrifugation of liposomes using deuterium oxide (D 2 O) as dispersion medium, vesicles entrapping BDP were separated as a floating creamy layer, whilst the free drug was sedimented as crystals. Drug entrapment was dependent on formulation composition and preparation method. When 1:15 w/w lipid to carrier was used, liposomes generated using the slurry method had an entrapment efficiency of 47.05% compared to 18.67% for those generated using the conventional proliposome method. By contrast, liposomes made by the thin-film hydration method had an entrapment efficiency of 25.66%. DSC studies using 50 mole% BDP demonstrated that the drug was amorphous in the proliposome formulation and tended to crystallize on hydration, resulting in low drug entrapment. In conclusion, a novel approach to the preparation of proliposomes using a slurry method has been introduced, offering higher entrapment for BDP than liposomes made using the conventional proliposome method and those prepared by thin-film hydration technique.
Entrapment of emblica extract in Liposome by microfluidization
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The aim of this work was to assess the impact of solvent selection on the microfluidic production of liposomes. To achieve this, liposomes were manufactured using small-scale and bench-scale microfluidics systems using three aqueous miscible solvents (methanol, ethanol or isopropanol, alone or in combination). Liposomes composed of different lipid compositions were manufactured using these different solvents and characterised to investigate the influence of solvents on liposome attributes. Our studies demonstrate that solvent selection is a key consideration during the microfluidics manufacturing process, not only when considering lipid solubility but also with regard to the resultant liposome critical quality attributes. In general, reducing the polarity of the solvent (from methanol to isopropanol) increased the liposome particle size without impacting liposome short-term stability or release characteristics. Furthermore, solvent combinations such as methanol/isopropanol mixtures ...
Le Lait, 2007
The isolation of milk fat globule membrane (MFGM) material from buttermilk on a commercial scale has provided a new ingredient rich in phospholipids and sphingolipids. In the pharmaceutical and cosmetic industries, highly purified phospholipids extracted from soya oil or egg yolk are used to produce liposomes. Liposomes are spherical structures consisting of one or more phospholipid bilayers enclosing an aqueous core. They may be used for the entrapment and controlled release of drugs or nutraceuticals, as model membranes or cells, and even for specialist techniques such as gene delivery. There are many potential applications for liposomes in the food industry, ranging from the protection of sensitive ingredients to increasing the efficacy of food additives. Our previous work compared the structure and properties of liposomes prepared from a milk fat globule membrane (MFGM) fraction and soya phospholipid material using a high-pressure homogenizer (Microfluidizer). These results identified some potential advantages in the use of MFGM phospholipids for the manufacture of liposomes for use in food systems. This paper compared the general structure and properties of liposomes prepared from the same MFGM phospholipid material using three different techniques-microfluidization, the traditional thin-film hydration and the heating method. The thin-film hydration technique required the use of organic solvents, while the other two methods do not involve any non food-safe chemicals. The liposomes prepared by both microfluidization and the heating method had high entrapment efficiencies. Liposomes produced via microfluidization tended to be significantly smaller than those produced by the other methods, with a narrower size distribution, and a higher proportion of unilamellar vesicles. There did not seem to be any advantages in the use of the thin-film hydration method, opening the door to the use of food-safe methods for liposome production. liposome / milk fat globule membrane / phospholipid / microfluidization
Homogeneous and reproducible liposome preparation relying on reassembly in microchannel laminar flow
Chemical Engineering Journal, 2010
We investigated a method for size homogenization of liposomes using microchannel laminar flow. This microchannel method combined with sonication produced the desired homogeneous liposome populations with size controlled by reassembly of liposomes in laminar flow, using simple operations that offer good reproducibility and organic-solvent free procedures. The liposome solution, which was prepared using the traditional method of film hydration, was loaded into a syringe. This liposome solution was sonicated while being transported into the capillary tubing using syringe injection. In both non-sonicated and sonicated batchwise preparations, liposomes displayed non-homogeneous and non-reproducible size profiles. On the other hand, homogeneous liposomes were obtained with good reproducibility using our microchannel method combined with sonication.
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Microfluidics and electrospraying, two revolutionary technologies with industrial potential for the microencapsulation of lipophilic bioactive ingredients, have been combined to produce hybrid liposome/protein microencapsulation structures in a semicontinuous process, reducing the number of steps required for their manufacture. Three different microfluidic mixing devices, one of them consisting of a simple straight microchannel (cross junction design) and the other two exhibiting patterned microchannels with different geometries (Tesla and 'splitting and recombination' designs), were used to mix a liposome suspension with a whey protein concentrate dispersion. The Tesla design showed the best mixing performance, as observed by fluorescence microscopy, so it was selected to be assembled to an electrospraying apparatus. The proposed in-line setup was successfully used to produce the micronsized encapsulation structures, as observed by scanning electron microscopy.
Application of experimental design to the formulation of glucose oxidase encapsulation by liposomes
Journal of Chemical Technology and Biotechnology, 2004
Fractional factorial screening design and response surface methodology were applied to optimize the entrapment of glucose oxidase in liposomes by the dehydration–rehydration vesicle (DRV) method. Phosphatidylcholine from different sources, cholesterol:phosphatidylcholine (Ch:PC) and enzyme:lipid (E:L) ratios, buffer pH, sonication frequency and trehalose concentration were the parameters selected for this study. The type of phosphatidylcholine was found to be the most important factor followed by the trehalose concentration, Ch:PC ratio, sonication frequency and E:L ratio. The pH did not play an important role in the response. By treating liposomes with trehalose, as cryoprotectant, the activity of entrapped enzyme decreased by 16%. Two of the factors (cholesterol:phosphatidylcholine and enzyme:lipid ratios) were further studied in a 32 central composite design. The optimized liposomal formulation with an entrapment efficiency of 24% was obtained for egg yolk PC with Ch:PC and E:L ratios of 0.95 and 14.69, respectively, at pH 6 and applying a sonication frequency of 150 W. Copyright © 2004 Society of Chemical Industry