Physical-Chemical Characterization and Formulation Considerations for Solid Lipid Nanoparticles (original) (raw)
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Influence of emulsifiers on the crystallization of solid lipid nanoparticles
Journal of Pharmaceutical Sciences, 2003
The crystallization temperature and polymorphism of tripalmitin nanoparticles in colloidal dispersions prepared by melt-homogenization and stabilized with different pharmaceutical surfactants (sodium glycocholate, sodium oleate, tyloxapol, Solutol HS 15, Cremophor EL) and their combinations with soybean phospholipid (Lipoid S100) were investigated to establish the influence of the emulsifiers on these parameters. There were no major effects on the crystallization temperature but remarkable differences in the time-course of polymorphic transitions after crystallization of the triglyceride particles indicate interaction between the surfactant layer and the triglyceride matrix. The metastable a-modification was most stable in dispersions solely stabilized with glycocholate. Upon fast cooling from the melt, these dispersions form an uncommon type of a-modification that displays only a very weak small-angle reflection indicating poor ordering between triglyceride layers. Slow crystallization of these glycocholate-stabilized nanoparticles yields the usual a-form. Electron microscopic investigations reveal that, in both cases, the particles in the a-modification are less anisometric than those of the stable b-form. These results indicate that major rearrangements still may take place in solid lipid nanoparticles after recrystallization.
Palestinian Medical and Pharmaceutical Journal, 2023
Nanocapsules are colloidal particles with dimensions measured in nanometers and generally obtained in the range of 100 to 500 nm through nanoencapsulation technologies. Nanoencapsulation encapsulates nano-sized particles in liquid or solid form to create nanocapsules or nanoparticles. Generally, six classical methods are involved in nanocapsule formation: nanoprecipitation, emulsification-diffusion, double emulsification, emulsification-coacervation, polymer coating, and layer-by-layer. Nanocapsules are prepared from different monomers and cross-linked polymers, contributing to their stability during and after encapsulation. They are segregated into ionic and non-ionic by the surface formal charges, which then influence the type of applications. The applications of nanocapsules usually range from developing targeted drug delivery systems, self-healing materials, and the encapsulation of nutritive additive compounds in nutraceutical products. Nowadays, people turn their attention to natural resources. Therefore, the polymer matrix and the active substances in nanocapsules have been adopted with various natural polymers such as protein, lipids, polysaccharides, plant metabolites, plant exudates, or plant extracts. Since nanotechnology products are predicted to be broadly utilized in the future, major key players must work collectively to handle the issue of safety regulation and user acceptance as well as optimum scale production of nanocapsules in industries.
A Comprehensive Review on Solid Lipid Nanoparticles
IJPPR, 2022
Polymeric nanoparticles can be used as an alternative compared to other classic colloidal carriers like liposomes, and emulsions due to their benefits such as controlled delivery of drugs, focused drug delivery, and enhanced stability, solid lipid nanoparticles were created in the early 1990s. This page provides a overview of the possible benefits and drawbacks of solid lipid nanoparticles, excipients, and all of the many techniques used to make them, including the membrane contractor approach. aspects of the stability of SLN and the impact of different excipients (used in the manufacturing of SLN) on stability, as well as other secondary stages involved in their stabilization, such as freeze drying, spray drying, etc. The issues surrounding SLN manufacture as well as the instrumental methods employed are extensively examined.
International Journal of Pharmaceutics, 2014
Alkyl polyglycosides (APGs) represent a group of nonionic tensides with excellent skin compatibility. Thus they seem to be excellent stabilizers for lipid nanoparticles for dermal application. To investigate this, different APGs were selected to evaluate their influence on the formation and characteristics of solid lipid nanoparticles (SLN). Contact angle analysis of the aqueous solutions/dispersions of the APGs on cetyl palmitate films revealed good wettability for all APG surfactants. Cetyl palmitate based SLN were prepared by hot high pressure homogenization and subjected to particle size, charge and inner structure analysis. 1% of each APG was sufficient to obtain SLN with a mean size between 150 nm and 175 nm and a narrow size distribution. The zeta potential in water was $ À50 mV; the values in the original medium were distinctly lower, but still sufficient high to provide good physical stability. Physical stability at different temperatures (5 C, 25 C and 40 C) was confirmed by a constant particle size over an observation period of 90 days in all dispersions. In comparison to SLN stabilized with classical surfactants, e.g., Polysorbate, APG stabilized SLN possess a smaller size, improved physical stability and contain less surfactant. Therefore, the use of APGs for the stabilization of lipid nanoparticles is superior in comparison to classical stabilizers. Further, the results indicate that the length of the alkyl chain of the APG influences the diminution efficacy, the final particle size and the crystallinity of the particles. APGs with short alkyl chain led to a faster reduction in size during high pressure homogenization, to a smaller particle size of the SLN and to a lower recrystallization index, i.e., to a lower crystallinity of the SLN. The crystallinity of the SLN increased with an increase in the alkyl chain length of APGs. Therefore, by using the tested APGs differing in the alkyl chain length, not only small sized and physically stable but also SLN with different sizes and crystallinity can be obtained. An optimized selection of these stabilizers might therefore enable the production of lipid nanoparticles with "tailor-made" properties.
Crystallization polymorphism and stability of nanostructured lipid carriers
The aim of this work was the development of nanostructured lipid carriers (NLC) using conventional fats and oils (soybean oil, SO and fully hydrogenated soybean oil, FHSO) for incorporation of free phytosterols (FP). FP are lipophilic bioactive compounds which can reduce blood cholesterol levels, through a competitive mechanism of absorption, aiding in the prevention of cardiovascular diseases. However, FP presents difficulties related to technological applications in foods due to the high melting point. In this way, NLC can be a means of making feasible incorporation of FP in foods. NLC were obtained in aqueous dispersion through the emulsification process, followed by high-pressure homogenization (HPH) using 3 and 5 cycles at 800 bar, with subsequent crystallization and stabilization of the lipid matrices (LM). The emulsifiers used were soybean lecithin (SL), ethoxylated sorbitan monooleate (T80) and sorbitan monostearate (S60). The thermal and crystalline behavior of the LM, FP and NLC were evaluated. NLCs were characterized by size and polydispersity. FP presented high crystallization (126°C) and melting (137°C) temperatures, but this did not avoid its incorporation into NLC. The NLC presented size between 154 to 534 nm and polydispersity ranging from 0.1 to 0.5, the lower limits being obtained with the T80. NLC were found to require lower temperatures to crystallize and polymorphic transitions were accelerated. This study indicated that the conventional raw materials were compatible with the development of NLC with FP.
ACS Omega
The aim of this work was to study the influence of process variables on the quality attributes of pomegranate extract loaded solid lipid nanoparticles (PE-SLNs) using Plackett− Burman design. PE-SLN formulations were prepared by hot homogenization followed by ultra-sonication technique and evaluated based on the dependent variables that were analyzed utilizing Statgraphics Centurion XV software. The lipid and surfactant (type and concentration), co-surfactant concentration, sonication time, and amplitude were selected as the independent variables (X 1 −X 7). The dependent parameters were particle size, polydispersity index, zeta potential, entrapment efficiency, and cumulative drug release (Y 1 −Y 5). Response surface plots, Pareto charts, and mathematical equations were generated to study the influence of independent variables on the dependent quality parameters. Out of seven variables, X 1 , X 2 , and X 6 have the main significant (p value < 0.05) effect on the entrapment efficiency, the cumulative drug release, the polydispersity index, respectively, while particle size was mainly affected by X 3 , X 6 and zeta potential by X 1 , X 3 , and X 4. Consequently, this screening study revealed that stearic acid as lipid, Tween 80 as surfactant, as well as sonication with short time and high amplitude can be selected for the development of PE-SLN formulation with minimum particle size, maximum zeta potential, highest entrapment, and sustained drug release behavior. Meanwhile, concentrations of lipid, surfactant, and co-surfactant are planned to be scaled up for further optimization study. In conclusion, the Plackett−Burman design verified its influence and significance in determining and understanding both process and formulation variables affecting the quality of PE-SLNs.
An Overview of Nanocapsule and Lipid Nanocapsule: Recent Developments and Future Prospects
Palestinian Medical and Pharmaceutical Journal, 2023
Nanocapsules are colloidal particles with dimensions measured in nanometers and generally obtained in the range of 100 to 500 nm through nanoencapsulation technologies. Nanoencapsulation encapsulates nano-sized particles in liquid or solid form to create nanocapsules or nanoparticles. Generally, six classical methods are involved in nanocapsule formation: nanoprecipitation, emulsification-diffusion, double emulsification, emulsification-coacervation, polymer coating, and layer-by-layer. Nanocapsules are prepared from different monomers and cross-linked polymers, contributing to their stability during and after encapsulation. They are segregated into ionic and non-ionic by the surface formal charges, which then influence the type of applications. The applications of nanocapsules usually range from developing targeted drug delivery systems, self-healing materials, and the encapsulation of nutritive additive compounds in nutraceutical products. Nowadays, people turn their attention to natural resources. Therefore, the polymer matrix and the active substances in nanocapsules have been adopted with various natural polymers such as protein, lipids, polysaccharides, plant metabolites, plant exudates, or plant extracts. Since nanotechnology products are predicted to be broadly utilized in the future, major key players must work collectively to handle the issue of safety regulation and user acceptance as well as optimum scale production of nanocapsules in industries.
Carbohydrate Polymers, 2012
Freeze-drying technique preserves the stability of nanoparticles. The objective of this study was optimization of freeze-drying condition of nano lipid carriers (NLCs). NLCs were prepared by emulsion-solvent evaporation followed by ultra-sonication method. Different carbohydrate and polymeric cryoprotectants including Microcelac ® (mixture of lactose and Avicel), Avicel PH102 (microcrystalline cellulose), mannitol, sucrose, Avicel RC591 (mixture of microcrystalline cellulose and sodium carboxymethyl cellulose), maltodextrine, Aerosil and PEG4000 were tested initially. The NLCs showing lower particle size growth and greater absolute zeta potential after freeze drying were chosen for further investigation using Taguchi optimization method. Studied factors included cryoprotectant type and concentration, freezing temperatures applied at different time periods and sublimation time. Sucrose, Avicel RC591 and Aerosil were selected as cryoprotectants from initial screening tests. Increasing their concentration increased the particle size. 1% of Avicel RC591, 24 h of freezing at −70 • C and 48 h sublimation time showed lower growth in particle size.
International Journal of Pharmacy and Pharmaceutical Sciences, 2016
Objective: Aim of the present study was to formulate solid lipid nanoparticles (SLNs) and to determine their physicochemical parameters when stored at cold temperature in aqueous solution (D-SLNs) prior to biological application. Methods: SLNs were formulated though nanoprecipitation technique which comprised of stearic acid (lipid), poloxamer 188 and lecithin (surfactant). Physicochemical parameters were estimated though particle size analysis, polydispersity index, surface morphology analysis (Scanning electron microscopy and Transmission electron microscopy) and cytotoxicity studies followed by live-dead staining through acridine orange and ethidium bromide. Results: SLNs with spherical morphology were successfully fabricated as revealed though SEM and TEM investigations. Fabricated SLNs had the mean particle size ranging from 188 nm (SLNs) to 327 nm (D-SLNs). Zeta potential was found to be±14mV to±6mV and polydispersity index was 0.297±0.18 for SLNs without incubation and 0.538±0.07 for SLNs after incubation. No cytotoxicity was observed for SLNs. Conclusion: SEM and TEM investigations showed morphological variation in SLNs and D-SLNs. Dissimilarity in mean particle size, zeta potential and polydispersity index indicates the increase in size and aggregation of nanoparticles. No cytotoxic effects of SLNs were observed in normal cells, suggesting storage of nanoformulation in the aqueous state has no effect in context to cytotoxicity. Hence we conclude that prolonged storage of formulation at cold temperature causes the deterioration of polymeric formulation.
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2016
Solid lipid nanoparticles (SLNs) are being investigated for their ability to encapsulate and protect lipophilic bioactive compounds in foods, supplements, and pharmaceuticals. In this study, the phase inversion temperature (PIT) method was used to fabricate SLNs using a model surfactant (Brij 30, C 12 E 4) / oil (octadecane) / water system. Surfactant/oil/water (SOW) mixtures were maintained at a temperature above the PIT, and then rapidly cooled to a temperature below the lipid nanoparticle crystallization point. The PIT ( 40°C) was determined by monitoring the turbidity versus temperature profile of the SOW system during heating. The lipid nanoparticle crystallization point, melting point, and physical state were determined using differential scanning calorimetry (DSC). The stability of the lipid nanoparticles after fabrication depended on the storage temperature relative to the PIT and melting/crystallization points. At temperatures appreciably below their melting point (26°C), the lipid nanoparticles were completely solid and stable to aggregation. At temperatures around their melting point, the lipid nanoparticles were partially crystalline, which led to partial coalescence and gelation. At temperatures appreciably above their melting point but below their PIT, the lipid nanoparticles were completely liquid and prone to coalescence and phase separation. These results have important implications for optimizing the fabrication and storage conditions required to produce stable nanoemulsions suitable for utilization in commercial products using low-energy methods.