Nondestructive rheological measurement of aqueous dispersions of solid lipid nanoparticles: effects of lipid types and concentrations on dispersion consistency

Seetapan, Nispa; Bejrapha, Piyawan; Srinuanchai, Wanwisa; Puttipipatkhachorn, Satit; Ruktanonchai, Uracha

doi:10.3109/03639040903586273

Cited by 13 publications

(11 citation statements)

References 34 publications

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“…21 Triglycerides with longer fatty acids produce platelets with higher aspect ratios that promote the formation of stacks and increase the viscosity of the suspensions. 26,41 Accordingly, the significantly higher critical concentration of 12% MMM for the isotropic−liquid crystalline phase transition found here for the MMM suspension with respect to the reported 9% PPP for PPP suspensions can be attributed to the lower aspect ratio for MMM platelets with respect to PPP platelets.…”

Section: ■ Theoretical Methodsmentioning

confidence: 47%

“…■ EXPERIMENTAL METHODS Sample Preparation. A native trimyristin suspension (20 wt % MMM, 4.8 wt % stabilizer, and 1.2 wt % costabilizer) was prepared by high pressure melt homogenization as follows: MMM (Dynasan 114, 98% purity, 26 Sasol GmbH, Witten, Germany) and the stabilizer S100, a purified soybean lecithin (≥94% phosphatidylcholine with mostly unsaturated C 18 fatty acids, 27 Lipoid GmbH, Ludwigshafen, Germany) were heated until a clear yellowish melt was obtained. Sodium glycocholate (NaGC, >98% purity, TCI Europe N.V., Zwijndrecht, Belgium) was dissolved in purified water and heated to the same temperature.…”

Section: ■ Introductionmentioning

confidence: 99%

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Liquid Crystalline Phase Formation in Suspensions of Solid Trimyristin Nanoparticles

et al. 2014

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The presence of liquid crystalline phases in suspensions of solid lipid nanoparticles can increase the risk of their gelling upon administration through fine needles. Here we study the formation of liquid crystalline phases in aqueous suspensions of platelet-like shaped solid lipid nanoparticles. A native lecithin-stabilized trimyristin (20 wt %) suspension was investigated at different dilution levels by small-angle X-ray scattering (SAXS) and visual inspection of their birefringence between two crossed polarizers. For trimyristin concentrations φMMM < 6 wt %, the dispersed platelets are well separated from each other whereas they start to self-assemble into stacked lamellae for 6 wt % ≤ φMMM < 12 wt %. For φMMM ≥ 12 wt %, the SAXS patterns become increasingly anisotropic, which is a signature of an evolving formation of a preferred orientation of the platelets on a microscopic scale. Simultaneously, the suspensions become birefringent, which proves the existence of an anisotropic liquid crystalline phase formed in the still low viscous liquid suspensions. Spatially resolved SAXS scans and polarization microscopy indicate rather small domains in the (sub)micrometer size range in the nematic liquid crystalline phase and the presence of birefringent droplets (tactoids). The observed critical concentrations for the formation of stacks and the liquid crystalline phase are significantly higher as for equivalent suspensions prepared from triglycerides with longer chains. This can be explained with the lower aspect ratio of trimyristin platelets. Special emphasis is put on the isotropic-liquid crystalline phase transition as a function of the ionic strength of the dispersion medium and φMMM. Higher salt concentrations allow shifting of the phase transition to higher trimyristin concentrations. This can be attributed to a partial screening of the repulsive forces between the platelets, which allows higher packing densities within the platelet stacks and of remaining isolated platelets.

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Section: ■ Theoretical Methodsmentioning

confidence: 47%

Section: ■ Introductionmentioning

confidence: 99%

Liquid Crystalline Phase Formation in Suspensions of Solid Trimyristin Nanoparticles

et al. 2014

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“…This promotes the formation of platelet stacks and increases the viscosity of the suspensions in the sequence trilaurin (12 : 0) < trimyristin (14 : 0) < tripalmitin (16 : 0) < tristearin (18 : 0). 19,21,25 Thus, not only ϕ st , but also ϕ lc can depend on the choice of the triglyceride and stabilizers and the preparation conditions. For tristearin suspensions it can be anticipated, that ϕ lc might be even lower than for the tripalmitin suspensions considered here.…”

Section: E Estimation Of the Critical Concentrationsmentioning

confidence: 99%

“…Parenteral administration requires suspensions which possess a low viscosity even when squeezed through narrow needles. 21,25 The liquid crystalline phases can adversely affect the rheological properties and the particle aggregation behavior and, through this, the (long-term) stability of such suspensions upon administration and storage. Two different lecithins are used for the stabilization of the dispersions, namely the pure lecithin DLPC and purified soybean lecithin (S100), the latter being often used for pharmaceutical purposes.…”

Section: Fig 1 2dmentioning

confidence: 99%

Formation of liquid crystalline phases in aqueous suspensions of platelet-like tripalmitin nanoparticles

Schmiele

Gehrer

Westermann

et al. 2014

The Journal of Chemical Physics

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Generation of frustrated liquid crystal phases by mixing an achiral nematic-smectic-C mesogen with an antiferroelectric chiral smectic liquid crystal J. Chem. Phys. 122, 144906 (2005) Suspensions of platelet-like shaped tripalmitin nanocrystals stabilized by the pure lecithin DLPC and the lecithin blend S100, respectively, have been studied by small-angle x-ray scattering (SAXS) and optical observation of their birefringence at different tripalmitin (PPP) concentrations ϕ PPP . It could be demonstrated that the platelets of these potential drug delivery systems start to form a liquid crystalline phase already at pharmaceutically relevant concentrations ϕ PPP of less than 10 wt. %. The details of this liquid crystalline phase are described here for the first time. As in a previous study [A. Illing et al., Pharm. Res. 21, 592 (2004)] some platelets are found to self-assemble into lamellar stacks above a critical tripalmitin concentration ϕ st P P P of 4 wt. %. In this study another critical concentration ϕ lc P P P ≈ 7 wt. % for DLPC and ϕ lc P P P ≈ 9 wt. % for S100 stabilized dispersions, respectively, has been observed. ϕ lc P P P describes the transition from a phase of randomly oriented stacked lamellae and remaining non-assembled individual platelets to a phase in which the stacks and nonassembled platelets exhibit an overall preferred orientation. A careful analysis of the experimental data indicates that for concentrations above ϕ lc P P P the stacked lamellae start to coalesce to rather small liquid crystalline domains of nematically ordered stacks. These liquid crystalline domains can be individually very differently oriented but possess an overall preferred orientation over macroscopic length scales which becomes successively more expressed when further increasing ϕ PPP . The lower critical concentration for the formation of liquid crystalline domains of the DLPC-stabilized suspension compared to ϕ lc P P P of the S100-stabilized suspension can be explained by a larger aspect ratio of the corresponding tripalmitin platelets. A geometrical model based on the excluded volumes of individual platelets and stacked lamellae has been developed and successfully applied to reproduce the critical volume fractions for both, the onset of stack formation and the appearance of the liquid crystalline phase.

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“…Therefore there is still room for improvement in the preparation of NLC for indomethacin encapsulation. The monoester cetyl palmitate and the medium chain triglyceride Miglyol 812 were chosen to be part of the lipid matrix due to their biocompatibility and biodegradability and excellent physical properties [44,45]. NLC were further coated with chitosan (CS) for its biocompatibility, biodegradability and ability to modify reversibly the tight [29] junctions between the cells, which makes this intestinal mucoadhesive hydrophilic polysaccharide a frequent component in nanocarriers for drugs intended to be orally administrated [46][47][48].…”

Section: Introductionmentioning

confidence: 99%

Polymeric Versus Lipid Nanoparticles: Comparative Study of Nanoparticulate Systems as Indomethacin Carriers

Carvalho

Lopes

Gonçalves

et al. 2015

J. Appl. Sol. Chem. Model.

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Encapsulation of nonsteroidal or non-steroidal anti-inflammatory drugs (NSAID) in nanocarrier systems aims to enhance bioavailability and to decrease toxicity of these drugs and thus improve the efficacy of treatments. With this aim two types of nanoparticles were prepared and compared: lipid nanoparticles, made of cetyl palmitate and Miglyol 812 which were uncoated or coated with chitosan; or polymeric nanoparticles, made of poly (DL-lactic-co-glycolic acid) (PLGA) for which different emulsion stabilizers were also tested (poly (vinyl alcohol) (PVA), and Pluronic F68). Nanoparticles were characterized for drug content and for particle size, charge and morphology. The lipid matrix was analyzed regarding its crystallinity by differential scanning calorimetry (DSC). The size of the nanoparticles was measured by dynamic light scattering (DLS) which indicated a unimodal particle size distribution in all systems. Nanoparticles' stability was confirmed by their highly negative surface charge in the case of polymeric and uncoated lipid nanoparticles, as analyzed by zeta potential measurements using electrophoretic light scattering (ELS). Lipid chitosan coated nanoparticles have also shown to be stable presenting highly positive surface charge. Results have further demonstrated that indomethacin is highly encapsulated regardless the type of particles. Morphological analysis by scanning electron microscopy has shown that the nanoparticles were smooth and spherical. The results gathered within the current study point to the conclusion that the proposed formulations provide nanoparticles of satisfactory quality to encapsulate indomethacin, which might be used to improve bioavailability of other NSAID in the treatment of inflammation.

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Nondestructive rheological measurement of aqueous dispersions of solid lipid nanoparticles: effects of lipid types and concentrations on dispersion consistency

Cited by 13 publications

References 34 publications

Liquid Crystalline Phase Formation in Suspensions of Solid Trimyristin Nanoparticles

Liquid Crystalline Phase Formation in Suspensions of Solid Trimyristin Nanoparticles

Formation of liquid crystalline phases in aqueous suspensions of platelet-like tripalmitin nanoparticles

Polymeric Versus Lipid Nanoparticles: Comparative Study of Nanoparticulate Systems as Indomethacin Carriers

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