Surface active properties of lipid nanocapsules.

Lipid nanocapsules (LNCs) are biomimetic nanocarriers used for the encapsulation of a broad variety of active ingredients. Similar to surface active compounds, LNCs contain both hydrophilic and hydrophobic parts in their structure. Moreover, the components of LNCs, macrogol 15 hydroxystearate (MHS) and lecithin, are known for their surface active properties. Therefore, the aim of this paper was to investigate the capability of the LNCs to decrease surface tension using two techniques: drop tensiometry and the Wilhelmy plate method. LNCs with diameters ranging from 30 to 100 nm were successfully obtained using a phase inversion technique. The LNCs' properties, such as size and zeta potential, depend on the composition. LNCs exhibit a lower limiting surface tension compared to MHS (34.8-35.0 mN/m and 37.7-38.8 mN/m, respectively), as confirmed by both drop tensiometry and the Wilhelmy plate method. LNCs have exhibited a saturated interfacial concentration (SIC) that was 10-fold higher than the critical micellar concentration (CMC) of MHS or the SIC of binary and ternary mixtures of LNC ingredients. The SIC of the LNC formulations depended on the mass mixing ratio of the MHS/triglycerides but not on the presence of lecithin. The CMC/SIC values measured by the Wilhelmy plate method were higher than those obtained using drop tensiometry because of the longer duration of the tensiometry measurement. In conclusion, the surfactant-like properties of the LNCs offer new possibilities for medical and pharmaceutical applications

Surface tension versus time of the MHS solution (50 mM) and LNC dispersion containing 50 mM MHS as determined by drop tensiometry.

<p>Surface tension versus time of the MHS solution (50 mM) and LNC dispersion containing 50 mM MHS as determined by drop tensiometry.</p

Saturated interfacial concentration (SIC) and limiting surface tension of the LNC formulations determined by the Wilhelmy plate method.

<p>The SIC is the concentration at which a sharp change in the slope has occurred. The limiting surface tension is the lowest surface tension observed for a given system regardless of the bulk concentration.</p

Composition and properties of the LNCs.

<p>MMR: mass mixing ratio, PS: particle size (mean ± S.D., n = 3), PDI: polydispersity index (mean ± S.D., n = 3), ZP: zeta potential (mean ± S.D., n = 3).</p

Critical micellar concentration (CMC), saturated interfacial concentration (SIC) and the limiting surface tension of the MHS solution and LNC dispersion as determined by drop tensiometry.

<p>The CMC/SIC is the concentration at which a sharp change in the slope has occurred. The concentrations (given in brackets) correspond to the calculated CMC/SIC based on the slope of the surface tension isotherms. The limiting surface tension is the lowest surface tension observed for a given system regardless of the bulk concentration.</p

Critical micellar concentration (CMC), saturated interfacial concentration (SIC) and the limiting surface tension of the MHS solution, LNC dispersion and binary and ternary mixtures of LNC components as determined by the Wilhelmy plate method.

<p>The CMC/SIC is the concentration at which a sharp change in the slope has occurred. The concentrations (given in brackets) correspond to the calculated CMC/SIC based on the slope of the surface tension isotherms. The limiting surface tension is the lowest surface tension observed for a given system regardless of the bulk concentration.</p