Characterisation and Skin Distribution of Lecithin-Based Coenzyme Q10-Loaded Lipid Nanocapsules

The purpose of this study was to investigate the influence of the inner lipid ratio on the physicochemical properties and skin targeting of surfactant-free lecithin-based coenzyme Q10-loaded lipid nanocapsules (CoQ10-LNCs). The smaller particle size of CoQ10-LNCs was achieved by high pressure and a lower ratio of CoQ10/GTCC (Caprylic/capric triglyceride); however, the zeta potential of CoQ10-LNCs was above /− 60 mV/ with no distinct difference among them at different ratios of CoQ10/GTCC. Both the crystallisation point and the index decreased with the decreasing ratio of CoQ10/GTCC and smaller particle size; interestingly, the supercooled state of CoQ10-LNCs was observed at particle size below about 200 nm, as verified by differential scanning calorimetry (DSC) in one heating–cooling cycle. The lecithin monolayer sphere structure of CoQ10-LNCs was investigated by cryogenic transmission electron microscopy (Cryo-TEM). The skin penetration results revealed that the distribution of Nile red-loaded CoQ10-LNCs depended on the ratio of inner CoQ10/GTCC; moreover, epidermal targeting and superficial dermal targeting were achieved by the CoQ10-LNCs application. The highest fluorescence response was observed at a ratio of inner CoQ10/GTCC of 1:1. These observations suggest that lecithin-based LNCs could be used as a promising topical delivery vehicle for lipophilic compounds

Physicochemical characterization of lipid nanoparticles and evaluation of their drug loading capacity and sustained release potential

Drug carrier systems based on lipid nanosuspensions prepared by melt emulsification present a number of severe stability problems such as a high gelation tendency, considerable particle growth and drug expulsion. Destabilization of the emulsified lipidic carriers is related to recrystallization of the lipids. The choice of stabilizers for colloidal lipid suspensions is, therefore, restricted. Systematic surface modifications are thus limited. In addition, the drug payload of crystalline nanosuspension particles is generally low. Improved stability and loading capacities were found for amorphous lipid nanoparticles which present the characteristic signals of supercooled melts in high resolution 1H-NMR. The NMR data indicate that such liquid but viscous carriers can, however, not immobilize the incorporated drug molecules to the same extent as a solid matrix. Sustained release over days or weeks as in slowly biodegraded solid matrices thus seems difficult to achieve with a supercooled melt. Attempts to combine the advantages of the solid crystalline lipids and the amorphous nature of the supercooled melts by generating solid but amorphous lipid suspension particles with a satisfactory long-term stability by a variation of the lipid matrix material have hitherto not been successful. Even a satisfactory stabilization of the α-modification using complex lipid mixtures to improve the loading capacity or to slow down the drug expulsion process could not be achieved. The rates of the polymorphic transitions were much higher in the colloidal lipid dispersions than in the bulk for the hard fats under investigation. Despite the fact that the properties of the lipids are superimposed with colloidal properties, significant differences between monoacid triglycerides and complex lipids were, however, found

Etoposide-incorporated tripalmitin nanoparticles with different surface charge: Formulation, characterization, radiolabeling, and biodistribution studies

Etoposide-incorporated tripalmitin nanoparticles with negative (ETN) and positive charge (ETP) were prepared by melt emulsification and high-pressure homogenization techniques. Spray drying of nanoparticles led to free flowing powder with excellent redispersibility. The nanoparticles were characterized by size analysis, zeta potential measurements, and scanning electron microscopy. The mean diameter of ETN and ETP nanoparticles was 391 nm and 362 nm, respectively, and the entrapment efficiency was more than 96%. Radiolabeling of etoposide and nanoparticles was performed with Technetium-99m (99mTc) with high labeling efficiency and in vitro stability. The determination of binding affinity of99mTc-labeled complexes by diethylene triamine penta acetic acid (DTPA) and cysteine challenge test confirmed low transchelation of99mTc-labeled complexes and high in vitro stability. Pharmacokinetic data of radiolabeled etoposide, ETN, and ETP nanoparticles in rats reveal that positively charged nanoparticles had high blood concentrations and prolonged blood residence time. Biodistribution studies of99mTc-labeled complexes were performed after intravenous administration in mice. Both ETN and ETP nanoparticles showed significantly lower uptake by organs of the reticuloendothelial system such as liver and spleen (P<.001) compared with etoposide. The ETP nanoparticles showed a relatively high distribution to bone and brain (14-fold higher than etoposide and ETN at 4 hours postinjection) than ETN nanoparticles. The ETP nanoparticles with long circulating property could be a beneficial delivery system for targeting to tumors by Enhanced Permeability and Retention effect and to brain