Browsing by Author "Silva, A.M."
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- Cationic solid lipid nanoparticles (cSLN): structure, stability and DNA binding capacity correlation studiesPublication . Doktorovova, S.; Shegokar, R.; Rakovsky, E.; Gonzalez-Mira, E.; Lopes, Carla Martins; Silva, A.M.; Martins-Lopes, P.; Muller, R.H.; Souto, Eliana B.Cationic solid lipid nanoparticles (cSLN) are promising lipid nanocarriers for intracellular gene delivery based on well-known and widely accepted materials. cSLN containing single-chained cationic lipid cetyltrimethylammonium bromide were produced by high pressure homogenization and characterized in terms of(a) particle size distribution by photon correlation spectroscopy (PCS) and laser diffractometry (LD), (b) thermal behaviour using differential scanning calorimetry (DSC) and (c) the presence of various polymorphic phases was confirmed by X-ray diffraction (WAXD). SLN composed of Imwitor 900PTM (IMW) showed different pDNA stability and binding capacity in comparison to those of Compritol 888 ATOTM (COM). IMW-SLN, having z-ave = 138–157 nm and d(0.5) = 0.15–0.158 m could maintain this size for 14 days at room temperature. COM-SLN had z-ave = 334 nm and d(0.5) = 0.42 m on the day of production and could maintain similar size during 90 days. IMW-SLN revealed improved pDNA binding capacity. We attempted to explain these differences by differentinteractions between the solid lipid and the tested cationic lipid.
- Modified rose bengal assay for surface hydrophobicity evaluation of cationic solid lipid nanoparticles (cSLN)Publication . Doktorovova, S.; Shegokar, R.; Martins-Lopes, P.; Silva, A.M.; Lopes, Carla Martins; Müller, R.H.; Souto, Eliana B.Surface hydrophobicity of nanocarriers influences protein binding and subsequently fate of nanoparticles in blood circulation. Therefore, characterization of surface hydrophobicity of nanocarriers provides important preclinical information. Here, a modified classical adsorption method for the needs of characterization of cationic solid lipid nanoparticles (cSLN) was developed. We have identified possible method limitations that should be considered when performing the analysis, i.e. the problems associated with particle separation from the dispersion and their own absorbance in visible spectrum. We propose two modified methods for performing the assay overcoming the stated limitations. We also discuss here evaluation by different approaches (calculation of binding constants or partitioning quotient) and their suitability for the prepared cSLN formulation. Overall, we confirmed that our modified adsorption method can provide useful information about surface properties of (cationic) SLN, however, performing and evaluation of the assay need special attention in order to obtain the desired results.