Nanoparticle lyophilization

The prepared nanoparticles can be stored in lyophilized form and resuspended in physiological solutions prior to administration. The procedure developed on the laboratory scale has been found amenable to scale-up productions. 

Solid lipid nanoparticles can be converted to solid dosage forms by, for example, granulation, whereby the SLN dispersion is used as the granulating fluid, or as the wetting agent in the extrusion process, or by spray-drying or lyophilizing the SLN dispersion. 

Heiati, H., Tawashi, R. and Phillips, N.C. (1998) Drug retention and stability of solid lipid nanoparticles containing azidothymidine palmitate after autoclaving, storage and lyophilization. J. Microencapsulation 15, 173-184. 

Siekmann, B. and Westesen, K. (1994) Melt-homogenized solid lipid nanoparticles stabilized by the nonionic surfactant tyloxapol. II. Physicochemical characterization and lyophilization. Pharm. Pharmacol. Lett. 3, 225-228. 

Nanoparticles can be lyophilized for storage without loss of bioactivity. 

Direct micelles contain lyophilic component of surface-active substance, whereas the reverse micelles contain lyophobic one. The miceUes can be formed in the presence and absence of water. In the case of reverse miceUes, for instance, in the hydrocarbon medium, water is easily solubilized, forming a water pool . Its size is characterized by the ratio of the water and surfactant volumes. Thus, a limited amount of water inside the micelle determines the kinetics and thermodynamics of the nanoparticles formation in a small micro/nanoreactor volume. 

Special care needs also to be taken to possible changes of the properties of the nanoparticles by preparation procedures (e.g. purification, lyophilization) and upon storage (e.g. polymorphic transitions of the matrix lipid, drug distribution in the... 

DNase I was passively adsorbed over 24 hours, 4°C, in situ to calcium phosphate nanoparticles that had been modified with a lyophilized film of adulterated... 

Diflerential Scanning Calorimetry (DSC). Calorimetric measurements were carried out by means of a Perkin-Elmer DSC8500 instrument equipped with an Intracooler 2 sub-ambient device and calibrated with purity indium standards. In order to measure the transitions of the nanoparticles, the external block temperature was set at —100 °C. A lyophilized solid powder of nanoparticles was used as sample with weight c.a. 2 mg. The powder was enclosed in aluminum pans and heated from -20 to 200 °C at a rate of 20 °C/min. Bulk sample was measured as received, enclosed in aluminum pans. 

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