Design, Preparation and Characterization of Modular Squalene-based Nanosystems for Controlled Drug Release

This article reviews the innovative and original concept the "squalenoylation", a technology allowing the formulation of a wide range of drug molecules (both hydrophilic and lipophilic) as nanoparticles. The "squalenoylation" approach is based on the covalent linkage between the squalene, a natural and biocompatible lipid belonging to the terpenoid family, and a drug, in order to increase its pharmacological efficacy. Fundamentally, the dynamically folded conformation of squalene triggers the resulting squalene-drug bioconjugates to self-assemble as nanoparticles of 100-300 nm. In general, these nanoparticles showed long blood circulation times after intravenous administration and improved pharmacological activity with reduced side effects and toxicity. This flexible and generic technique opens exciting perspectives in the drug delivery field.

Influence of the nanoprecipitation conditions on the supramolecular structure of squalenoyled nanoparticles

Hydrophobic organic compounds dissolved in a polar solvent can self-assemble into nanoparticles (NPs) upon nanoprecipitation into water. In the present study, we have investigated the structure of squalenacetyl-adenosine (SQAc-Ad) nanoparticles which were previously found to exhibit impressive neuroprotective activity. When obtained by nanoprecipitation of a SQAc-Ad ethanolic solution into water, two different supramolecular organizations of SQAc-Ad NPs were evidenced, depending on the water-to-ethanol volume ratio. It has been shown that a fraction of the solvent remained associated with the NPs, despite prolonged evaporation under reduced pressure after nanoprecipitation, and that this residual solvent dramatically affected their structure. This study points to the importance of being in the "Ouzo" region to minimize the amount and effect of residual solvent and to control the structure of NPs.

Nanoprecipitation and the "Ouzo effect": Application to drug delivery devices

Biodegradable nanocarriers such as lipid- or polymer-based nanoparticles can be designed to improve the efficacy and reduce the toxic side effects of drugs. Under appropriate conditions, nanoprecipitation of a hydrophobic compound solution in a non-solvent can generate a dispersion of nanoparticles with a narrow distribution of sizes without the use of surfactant ("Ouzo" effect). The aim of this review is to present the main parameters controlling the nucleation and growth of aggregates in a supersaturated solution and the characteristics of the obtained nanoparticles. The importance of the kinetics of mixing of the solution containing the hydrophobic compound and the non-solvent is highlighted. Illustrative examples of polymeric nanoparticles for drug delivery or terpenoid-based nanoprodrugs obtained by nanoprecipitation are reported.