Solid Lipid Nanoparticles Technique - Ultrasonication or high speed homogenization

SLN can also obtained by high speed stirring or sonication. The equipment used in this process is very common in every lab.

The disadvantages of this method are:
• broader particle size distribution ranging into micrometer range
• physical instabilities (particle growth upon storage)
• Potential metal contamination due to ultrasonication

To make a stable formulation, studies have been performed by various research groups that high speed stirring and ultrasonication are used combined and performed at high temperature.0

Solid Lipid Nanoparticles Technique - solvent emulsification/evaporation method

For the production of nanoparticle dispersions by precipitation in o/w emulsions the lipophilic material is dissolved in water-immiscible organic solvent (cyclohexane) that is emulsified in an aqueous phase. Upon evaporation of the solvent nanoparticle dispersion is formed by precipitation of the lipid in the aqueous medium. The mean diameter of the obtained particles was 25 nm with cholesterol acetate as model drug and lecithin/sodium glycocholate blend as emulsifier.

The reproducibility of the result was confirmed by Siekmann and Westesen, who produced the cholesterol acetate nanoparticles of mean size 29 nm. Micro emulsion based SLN preparations: the dilution of Microemulsions. Stirring an optically transparent mixture at 65-700 which is typically composed of a low melting fatty acid (stearic acid), an emulsifier (polysorbate 20, polysorbate 60, soy phosphatidylcholine, and sodium taurodeoxycholate), co-emulsifiers (sodium monooctylphosphate) and water. The hot microemulsion is dispersed in cold water (2-30) under stirring. Typical volume ratios of the hot microemulsion to cold water are in the range of 1:25 to 1:50. The dilution process is critically determined by the composition of the microemulsion. According to the literature, the droplet structure is already contained in the microemulsion and therefore, no energy is required to achieve submicron particle sizes.

Fessi produced polymer particles by dilution of polymer solutions in water. The particle size is critically determined by the velocity of the distribution processes. Nanoparticles were produced only with solvents which distribute very rapidly into the aqueous phase (acetone), while larger particle sizes were obtained with more lipophilic solvents. The hydrophilic co-solvents of the microemulsion might play a similar role in the formation of lipid nanoparticles as the acetone for the formation of polymer nanoparticles.

Solid Lipid Nanoparticles Technique - supercritical fluid method

The advantage of this technique is solvent-less processing. There are several variations in this platform technology for powder and nanoparticle preparation. SLN can be prepared by the rapid expansion of supercritical carbon dioxide solutions (RESS) method. Carbon dioxide (99.99%) was the good choice as a solvent for this method.

Solid Lipid Nanoparticles Technique - Spray drying method

It’s a cheaper method than lyophilization, transform an aqueous SLN dispersion into a drug product.. This method cause particle aggregation due to high temperature, shear forces and partial melting of the particle. Better use of lipid with melting point >700 for spray drying. The best result was obtained with SLN concentration of 1% in a solution of trehalose in water or 20% trehalose in ethanol-water mixtures (10/90 v/v).

Solid Lipid Nanoparticles Technique - Double emulsion method

This method developed based on solvent emulsification-evaporation. Here the drug is encapsulated with a stabilizer to prevent drug partitioning to external water phase during solvent evaporation in the external water phase of w/o/w double emulsion.


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Solid Lipid Nanoparticles : New Pharmaceutical Delivery System