Effect of fullerene on the dispersibility of nanostructured lipid particles and encapsulation in sterically stabilized emulsions

We report on the effect of fullerenes (C60) on the stability of nanostructured lipid emulsions. These (oil-in-water) emulsions are essentially aqueous dispersions of lipid particles exhibiting self-assembled nanostructures at their cores. The majority of previous studies on fullerenes were focused on planar and spherical lipid bilayer systems including pure lipids and liposomes. In this work, fullerenes were interacted with a lipid that forms nanostructured dispersions of non-lamellar self-assemblies. A range of parameters including the composition of emulsions and sonication parameters were examined to determine the influence of fullerenes on in-situ and pre-stabilized lipid emulsions. We found that fullerenes mutually stabilize very low concentrations of lipid molecules, while other concentration emulsions struggle to stay stable or even to form at first instance; we provide hypotheses to support these observations. Interestingly though, we were able to encapsulate varying amounts of fullerenes in sterically stabilized emulsions. This step has a significant positive impact, as we could effectively control an inherent aggregation tendency of fullerenes in aqueous environments. These novel hybrid nanomaterials may open a range of avenues for biotechnological and biomedical applications exploiting properties of both lipid and fullerene nanostructures

Self-Assembled Lipid Cubic Phase and Cubosomes for the Delivery of Aspirin as a Model Drug

Three-dimensionally organized lipid cubic self-assemblies and derived oil-in-water emulsions called “cubosomes” are attractive for various biotechnological applications due to their ability to be loaded with functional molecules and their associated sustained release properties. Here, we employed both of these lipid-based systems for the delivery of a model drug, aspirin, under comparable conditions. Studies were performed by varying drug-to-lipid ratio and the type of release medium, water and phosphate buffer saline (PBS). Release rates were determined using UV−vis spectroscopy, and small-angle X-ray scattering was used to confirm the type of self-assembled nanostructures formed in these lipid systems. The release from the bulk lipid cubic phase was sustained as compared to that of dispersed cubosomes, and the release in PBS was more efficient than in water. The tortuosity of the architecture, length of the diffusion pathway, type of nanostructure, and physicochemical interaction with the release media evidently contribute to these observations. This work is particularly important as it is the first report where both of these nanostructured lipid systems have been studied together under similar conditions. This work provides important insights into understanding and therefore controlling the release behavior of lipid-based drug nanocarriers

Lipid-hydrogel films for sustained drug release

We report a hybrid system, fabricated from nanostructured lipid particles and polysaccharide based hydrogel, for sustained release applications. Lipid particles were prepared by kinetically stabilizing self-assembled lipid nanostructures whereas the hydrogel was obtained by dissolving kappa-carrageenan (KC) in water. The drug was incorporated in native as well as lipid particles loaded hydrogels, which upon dehydration formed thin films. The kinetics of drug release from these films was monitored by UV–vis spectroscopy while the films were characterized by Fourier transform infra-red (FTIR) spectroscopy and small angle X-ray scattering techniques. Pre-encapsulation of a drug into lipid particles is demonstrably advantageous in certain ways; for instance, direct interactions between KC and drug molecules are prohibited due to the mediation of hydrophobic forces generated by lipid tails. Rapid diffusion of small drug molecules from porous hydrogel network is interrupted by their encapsulation into rather large sized lipid particles. The drug release from the lipid-hydrogel matrix was sustained by an order of magnitude timescale with respect to the release from native hydrogel films. These studies form a strong platform for the development of combined carrier systems for controlled therapeutic applications