Lyophilization of Nanocapsules: Instability Sources, Formulation and Process Parameters.

Polymeric nanocapsules have gained more and more interest in the medical sciences. Their core-shell structure offers numerous advantages, especially regarding their use as drug delivery systems. This review begins by presenting the different intrinsic sources of the instability of nanocapsules.

Investigation of alternative organic solvents and methods for the preparation of long-circulating and pH-sensitive liposomes containing cisplatin.

Recent studies using long-circulating and pH-sensitive liposomes containing cisplatin (SpHL-CDDP) have resulted in a formulation with improved pharmacokinetic, toxicity and tumor localization properties. In this study, SpHL-CDDP were prepared in both laboratory and pilot scales. This study evaluated the possibility of using the dehydration-rehydration method, as well as using alternative organic solvents (ethyl acetate/ethanol mixtures at 2:1 and 1:1 volume ratios), for the preparation of liposomes by the reverse-phase evaporation (REV) method.

Preparation, characterization and in vitro evaluation of a new nucleotide analogue prodrug cyclodextrin inclusion complexes.

Bis(tbutyl-S-acyl-2-thioethyl)-cytidine monophosophate is a new cytotoxic mononucleotide prodrug which have been developed to reverse the cellular resistance to nucleoside analogues. Unfortunately, its in vivo utilisation was hampered by its poor water solubility, raising the need of a molecular vector capable to mask its physicochemical characteristics although without affecting its cytotoxic activity. Hydroxypropyl-beta-cyclodextrin was used to prepare the prodrug inclusion complexes, allowing it to be solubilized in water and hence to be used for in vitro and in vivo experiments.

Sulfated and non-sulfated amphiphilic-beta-cyclodextrins: impact of their structural properties on the physicochemical properties of nanoparticles.

Purpose: The aim of this work was to study the preparation of nanospheres from amphiphilic beta-cyclodextrins formed (a) by different acylation degrees (DA) at the secondary hydroxyl face (DA=14 and 21) followed by varying (b) the sulfatation degrees (DS) at the primary hydroxyl face (DS=0, 4 and 7).

Methods: The physicochemical properties of the synthesized compounds such as molecular weights, the theoretical HLB values and the critical micellar concentration values and their surface area were presented. The nanoparticles prepared from amphiphilic beta-cyclodextrins were characterized by mean size, zeta potential and their morphology.

Nucleoside analogue delivery systems in cancer therapy.

Nucleoside analogues (NAs) are important agents in the treatment of hematological malignancies. They are prodrugs that require activation by phosphorylation. Their rapid catabolism, cell resistance and overdistribution in the body jeopardize nucleoside analogue chemotherapy.

Spray-drying nanocapsules in presence of colloidal silica as drying auxiliary agent: formulation and process variables optimization using experimental designs.

Purpose: Spray-drying process was used for the development of dried polymeric nanocapsules. The purpose of this research was to investigate the effects of formulation and process variables on the resulting powder characteristics in order to optimize them.

Materials And Methods: Experimental designs were used in order to estimate the influence of formulation parameters (nanocapsules and silica concentrations) and process variables (inlet temperature, spray-flow air, feed flow rate and drying air flow rate) on spray-dried nanocapsules when using silica as drying auxiliary agent.

Freeze-drying of nanoparticles: formulation, process and storage considerations.

Freeze-drying has been considered as a good technique to improve the long-term stability of colloidal nanoparticles. The poor stability in an aqueous medium of these systems forms a real barrier against the clinical use of nanoparticles. This article reviews the state of the art of freeze-drying nanoparticles.

Freeze-drying of nanocapsules: impact of annealing on the drying process.

Freeze-drying process was recently applied to improve the long-term storage stability of nanocapsules. Thermal treatment by annealing is an interesting process to optimize a freeze-drying cycle of these colloidal vectors. The objective of this paper is to investigate the impact of annealing on primary and secondary drying characteristics and on nanocapsules (NC) properties.

Investigation of nanocapsules stabilization by amorphous excipients during freeze-drying and storage.

Freeze-drying was recently applied to improve the long-term storage stability of nanoparticles. Nanocapsules have a thin polymeric envelope that may not withstand the stresses of such process. So, cryoprotectants and lyoprotectants are usually added to the formulation to protect these vectors during freezing and desiccation steps.

A pilot study of freeze drying of poly(epsilon-caprolactone) nanocapsules stabilized by poly(vinyl alcohol): formulation and process optimization.

A common limitation of using polymeric nanoparticles in aqueous suspension is due to their poor chemical and physical stability when conserved for a long time. Therefore, freeze drying of these colloidal systems is an alternative method to achieve long-term stability. Nanocapsules have thin and fragile shell structure, which may not resist to the stress of such process.

Synthesis and characterisation of novel nanospheres made from amphiphilic perfluoroalkylthio-beta-cyclodextrins.

This work describes the synthesis of new amphiphilic perfluorohexyl- and perfluorooctyl-propanethio-beta-cyclodextrins and the comparison of the ability of these molecules and alkyl analogue, nonanethio-beta-cyclodextrin to form nanospheres. Nanospheres were prepared using nanoprecipitation method (perfluoroalkylthio-beta-cyclodextrin in THF [0.11 x 10(-3)M], stirring rate 700rpm, addition of aqueous phase at 64 degrees C into organic phase at 50 degrees C).

Synthesis and characterisation of sulfated amphiphilic alpha-, beta- and gamma-cyclodextrins: application to the complexation of acyclovir.

The synthesis of sulfated amphiphilic alpha-, beta- and gamma-cyclodextrins was achieved according to the standard protection-deprotection procedure. The formation of inclusion complexes between the amphiphilic alpha-, beta- and gamma-cyclodextrins and an antiviral molecule, acyclovir (ACV) was investigated by UV-visible spectroscopy (UV-Vis) and electrospray ionisation mass spectrometry (ESIMS). UV-Vis spectroscopy allowed determination of the stoichiometry and stability constants of complexes, whereas ESIMS, a soft ionisation technique, allowed the detection of the inclusion complexes.

Scanning electron microscopy and atomic force microscopy imaging of solid lipid nanoparticles derived from amphiphilic cyclodextrins.

Scanning electron microscopy (SEM) and atomic force microscopy (AFM) have been applied to the imagery of solid lipid nanoparticles (SLNs) formulated from an amphiphilic cyclodextrin, 2,3-di-o-alkanoyl-beta-cyclodextrin, beta-CD21C6. Comparison of the results shows that the vacuum drying technique used in sample preparation for SEM causes shrinkage in the size of the SLNs, whereas the deposition method used for AFM causes the SLNs to form small clusters. The hydrodynamic diameter determined from photon correlation spectroscopy (PCS) is 359+/-15 nm and the zeta potential is -25 mV.