Simulated gastrointestinal digestion of inclusion complexes based on ovalbumin nanoparticles and conjugated linoleic acid.

The objective of this work was to obtain and characterize conjugated linoleic acid (CLA) delivery systems based on ovalbumin nanoparticles (OVAn1 and OVAn2) and to study their behaviour under a standardised static in vitro digestion model. OVAn1 and OVAn2 were obtained by heat treatment (85 °C, 5 min, pH 11.35 and 7.5, respectively). OVAn1 and OVAn2 had hydrodynamic diameters of 24.63 ± 0.04 and 92.0 ± 0.2 nm, respectively, showing no significant differences in ζ potential values (p < 0.05) at pH 7.0. CLA nanocomplexes were examined in terms of size and ζ potential at pH 3.0 and 7.0, highlighting that binding of CLA caused an increase in size for OVA and both OVA nanoparticles. Morphological characterization was performed by confocal laser scanning microscopy (CSLM) finding that OVA and OVA nanoparticles had a circular shape. Also, the CLA encapsulation efficiency (EE) for OVA and OVA nanoparticles was studied, yielding EE values greater than 97% for all systems. Finally, systems were assayed for a standardized in vitro gastrointestinal digestion model considering gastric and intestinal steps. Macroscopic appearance, CSLM images and quantification of CLA retention by HPLC were evaluated after digestion. All the systems showed the formation of macroscopic aggregates both in gastric and intestinal phases, which generated a visible precipitate. In all systems, CSLM confirmed the presence of numerous undefined-form aggregates. Finally, high CLA retention (around 99%) was found for native protein and nanoparticles.

Formation and characterization of self-assembled bovine serum albumin nanoparticles as chrysin delivery systems.

Chrysin (5,7-dihydroxyflavone) (Chrys) is a natural flavone extracted from many plants, and it has been proposed as a bioactive agent for cancer therapy. Nevertheless, its use is limited mainly due to its poor water solubility. Bovine serum albumin (BSA) is a water soluble, biocompatible and non-toxic protein with a promising application in lipophilic bioactive compound delivery. Moreover, BSA is heat sensitive, feature that could be used for producing self-assembled nanoparticle with tailor-made properties. In this contribution, we studied the formation of BSA nanoparticles (BSAnp) by thermal treatment at different conditions of temperature (70 °C/5 min and 85 °C/5 min), protein concentration (1.0-4.0%wt.) and aqueous medium pH values (9.0 and 11.0) in which it is known that BSA is found in different unfolded conformations. Binding of Chrys dissolved in dimethyl sulfoxide (DMSO) was studied by fluorescence titration experiments. Characterization of Chrys-loaded and unloaded BSAnp was performed in phosphate buffered saline (PBS) pH 7.4 by applying a set of complementary techniques: dynamic light scattering (DLS), size exclusion fast protein liquid chromatography (SEC-FPLC) and transmission electron microscopy (TEM). Different populations of BSAnp were obtained, which showed different diameters in the range of 1328 nm, ζ potentials around -10.0 mV, molecular weight in the range of 400-1000 kDa and spherical shape. Chrys encapsulation efficiency (EE. %) was also determined, and values between 44-84% were obtained, which mainly depended on the mode of Chrys binding and physicochemical BSAnp properties. Results highlight the ability of self-assembled BSAnp for Chrys vehiculization in an aqueous medium which could found potential application in antitumor therapies.