Characterization Of Solid Lipid Microparticles Research Articles

Production and characterization of promising β-stable seed crystals to modulate the crystallization of fat-based industrial products.

Spray cooling or spray chilling is a technique for obtaining solid lipid microparticles (SLMs) within the diameter range in micrometers using low temperatures and no organic solvents. It is a low-cost technique and is easy to scale-up. The production of SLMs into β-form represents a technological challenge due to the fast crystallization given by the spray cooling system, which generally results in SLMs crystallized into the metastable polymorphic form α. This study focuses on the production and characterization of SLMs by spray cooling using hard fat soybean oil (HS) added of D-limonene or canola oil, aiming to their application as β-seed crystals into lipid systems. The β-seed crystals could turn into an alternative lipid material to be used in fat-based products that present the preferential β' crystallization, like palm oil, increasing its compatibility with cocoa butter (CB) and allowing for the development of substitutes. The obtained SLMs showed spherical geometry and no agglomeration during storage at 25°C for up to 30days, verified by scanning electron microscopy (SEM). The mean diameters (D50) were between 150 and 200μm and the β' and β-form, determined by X-ray diffraction (XRD), appeared immediately after the crystallization process by spray cooling using HS added of 5% D-limonene (the HS control sample presented only the α-form). The SLMs of this study demonstrated their potential use as β-seed crystals into lipid systems.

Production and characterization of solid lipid microparticles loaded with guaraná (Paullinia cupana) seed extract.

Guaraná is a native fruit of the Amazon rainforest, which presents high levels of phenolic compounds. However, these bioactive compounds may be unstable in food processing and gastrointestinal conditions. Thus, this work aimed to characterize guaraná seed extract (GSE) followed by microencapsulation using a spray-chilling method and with vegetable fat as carrier, as well as to evaluate the particles. Phenolic-rich GSE was produced using 50% (w/w) hydroalcoholic solution and dehydrated by spray drying and lyophilization. Powdered GSE was characterized in relation to its inhibitory activity on digestive enzymes. Solid lipid microparticles (SLM) were evaluated for the retention of bioactive compounds and the release profile of phenolic compounds in simulated gastrointestinal conditions. Powdered GSE showed anti-obesity potential due to the high inhibitory activity of lipase. Regarding the retention of phenolic compounds, at least 75% were detected after 90 days at 25 °C in SLM. Moreover, SLM loaded with 7.5% GSE released approximately 99% of phenolic compounds in simulated gastrointestinal conditions. These results show the efficiency of spray chilling for protection and release of phenolic compounds from GSE, allowing future application in food.

Formulation and Characterization of Solid Lipid Microparticles

Formulation and Characterization of Solid Lipid Microparticles

Formulation and Evaluation of Novel Solid Lipid Microparticles for the Sustained Release of Ofloxacin

The aim of this study was to prepare solid lipid microparticles (SLM) with incorporated ofloxacin, suitable for oral delivery. Ofloxacin-loaded SLM were prepared using stearic acid and chloroform as lipid matrix and Tween-80 as surfactant, by high shear homogenization technique and followed by lyophilization. The physiochemical characterization of SLMs were investigated by scanning electron microscopy, transmission electron microscopy, zeta potential, zone of inhibition, in-vitro study, ex-vivo study and stability study. The result demonstrated that the entrapment efficiency, particle size and zeta potential of microparticles were 86.02%, 203.7nm and -32.68mv, respectively. The in-vitro and ex-vivo studies showed sustained release of drug from formulation. These results indicate that SLM might be a promising delivery system to enhance the pharmacological activity of ofloxacin.

Production by spray chilling and characterization of solid lipid microparticles loaded with vitamin D3

Spray chilling is a promising technology for immobilization of fat-soluble vitamins since solid lipid microparticles (SLM) can protect, release and improve their absorption in the gut. Thus, this work aimed to produce SLM loaded with 0.1% of vitamin D3 by spray chilling using vegetable fat as carrier, and some formulations were added of 1% beeswax and 1% soy lecithin to evaluate their effect on vitamin stability. SLM were characterized by scanning electron microscopy, laser diffraction and X-ray diffraction (XRD). Additionally, vitamin D3 stability was evaluated during 65days of storage at 10 and 25°C through periodic measurements by high-performance liquid chromatography (HPLC). SLM were spherical with unimodal size distribution and volume weighted mean diameter (D4,3) varied from 83.0 to 98.6μm. XRD analyses revealed that SLM presented β′ type crystals, which contributes to a better stability and sensorial properties. SLM increased vitamin stability at 25°C, in which 86.3% of vitamin were detected after 65days (formulation with 1% beeswax), compared with non-immobilized vitamin at same conditions (60.8%). These results are promising and demonstrate the potential of spray chilling for production of SLM loaded with vitamin D3, encouraging future applications in foods.

Preparation and characterization of solid lipid microparticles with liquid crystal structure

ABSTRACTThe aim of this study was the preparation and characterization of solid lipid microparticles (SLMs) with liquid crystal structure. In order to observe the morphology of SLMs, environmental emission scanning electron microscopy was employed. And the structure of particles measured by polarized light optical microscopy and X-ray diffraction. Differential scanning calorimetry (DSC) was used to measure the crystallinity. Karl Fischer Titration were used to measure the micro amount of water content. The optimal formation was prepared. The influence of homogenization rate, emulsification temperature, concentration of NaCl, co-emulsifier type and concentration on particle size was discussed.

Development and characterization of solid lipid microparticles containing vitamin C for topical and cosmetic use

Solid lipid microparticles (SLMs), combined with the advantages of double emulsions (W/O/W) and water‐in‐oil micro emulsions, are developed for transdermal administration. A modified one‐step emulsification method was introduced, which made the industrial production of SLMs easier. Variables involved in preparation that may affect the solubility, stability, and entrapment efficiency of SLMs were investigated. With vitamin C as a model active, the advantages of SLMs in transdermal administration were studied further. Vitamin C, encapsulated by SLMs, exhibited an enhanced storage stability up to 1 month under 25°C and a sustained releasing profile over 24 h. Furthermore, the SLMs was very helpful in delivering vitamin C molecules into skin through stratum corneum. The result showed 5.52‐fold (p < 0.05) increased absorption of vitamin C, compared to the vitamin C solution. These studies demonstrate that SLMs could be a promising method for facilitating transdermal penetration of active ingredients with high solubility and low permeability.Practical applications: SLMs could be used as a drug delivery system for hydrophilic active ingredients with low permeability. Experiments have shown better stability and skin permeability of vitamin C incorporated in SLMs when compared with pure vitamin C. Furthermore, the method of producing SLMs is simple and can be realized in a way of industrial production. Since SLMs can dissolve in water, SLMs can be directly used on wet skin with excellent skin‐touch feel. As a result, SLMs could be a practical delivery system for hydrophilic compounds with low permeability in many applications such as pharmaceuticals and cosmetics.Solid lipid microparticles (SLMs), combined with the advantages of double emulsions (W/O/W) and water‐in‐oil micro emulsions, are developed for transdermal administration. A modified one‐step emulsification method was introduced, which made the industrial production of SLMs easier. With vitamin C as a model active, the advantages of SLMs in transdermal administration were studied further. Vitamin C, encapsulated by SLMs, showed an enhanced storage stability up to 1 month and a sustained releasing profile over 24 h. Furthermore, the SLMs can facilitate skin's absorption of VC with pig as the model animal. These studies demonstrate that SLMs can be a promising method for facilitating transdermal penetration of active ingredients with high solubility and low permeability.

Solid lipid microparticles produced by spray chilling technique to deliver ginger oleoresin: Structure and compound retention

Ginger oleoresin (GO) is frequently used as a flavor ingredient in various foods. Besides flavoring, its bioactive compounds are known for antimicrobial and antioxidant properties. In this study, we investigated the formation and characterization of solid lipid microparticles (SLMs) loaded with GO by the spray chilling technique. Mixtures composed of palmitic acid with oleic acid or palm fat were used as carriers. DSC and X-ray diffraction showed that the particle crystalline structure was decreased by oleic acid. Retention of pungent and volatile compounds was higher than 96% and 75%, respectively, in the best formulations. FTIR spectroscopy revealed no chemical interaction between GO and carriers. The particles presented a spherical shape and rough surface, and GO was dispersed over the entire particles, as shown by confocal microscopy. High volatile and pungent compound retention have shown that spray chilling can be a very promising technique for the production of SLM loaded with GO.

Production and structural characterization of solid lipid microparticles loaded with soybean protein hydrolysate

The aims of this study were to produce and evaluate solid lipid microparticles (SLMs) loaded with soy protein hydrolysate (HP). The SLMs were produced by spray chilling with an active material and carrier ratio of 1:5 and 1:10 and in two feed preparations: emulsion and suspension. The rheological parameters of the feeds produced by emulsions were studied, morphological characteristics of the SLMs were examined via scanning electron microscopy (SEM) and confocal microscopy, the particle size and distribution were measured via laser light diffraction, and the structural properties of the SLMs were characterized via infrared (FTIR) spectroscopy and X-ray diffraction (XRD). SEM images showed that SLMs were spherical and agglomerated. The analysis of X-ray diffraction indicated that the microparticles after 90days of storage had β polymorphic form. The preparation methods for feeds, emulsion and suspension, had no influence on the rheological parameters, and the median particle size of the SLMs and interactions between the ingredients were not detected via FTIR spectroscopy; however, the SLMs prepared by emulsion contained pores and had a higher incorporation efficiency of HP. The spray chilling technique is suitable method for microencapsulation of soy protein hydrolysate. So, this technique could be useful for attenuating HP unpleasant taste, for its protection and also for promoting its release in the intestine, during fat digestion.

Development and characterization of solid lipid microparticles loaded with ascorbic acid and produced by spray congealing

The aim of this work was to produce solid lipid microparticles loaded with ascorbic acid (AA). The microparticles were produced using spray congealing technique with a theoretical AA loading of 15, 25 or 40% (w/w). Fully hydrogenated palm oil and vegetable glycerol monostearate were used as carriers. The microparticles were characterized in terms of yield, morphology (SEM), mean size, size distribution, thermal behavior (DSC), encapsulation efficiency and stability of AA. The microparticles were spherical, the process yield was over 81% and the encapsulation efficiency ranged from 74 to 84%. The stability of the encapsulated AA was over 75% after 56days of storage. The type of carrier, the AA concentration and the storage temperature did not significantly influence the stability. In conclusion microencapsulation by spray congealing is an important alternative to ensure AA stability, even at temperatures higher than those commonly used in food storage.

Development and Characterization of Solid-Lipid Microparticles of Highly Insoluble Drug Sirolimus

Solid lipid microparticles (SLMs) represent an alternative carrier system to traditional colloidal carrier such as emulsion, liposomes and polymeric micro and nanoparticles. The purpose of this research work was to develop and evaluate solid lipid microparticles of sirolimus for oral delivery. Sirolimus is an immunosupressive drug used to prevent transplant rejection and to treat auto immune diseases. It is a macrolide lactone produced by streptomyces hydroscopicus . It is extremely hydrophobic. Sirolimus solid lipid microparticles were prepared by hot homogenization technique. The matrix chiefly consisted of glyceryl monostearate and sodium taurocholate. The SLMs were studied for its particle size analysis, drug content, entrapment efficiency, in vitro release characteristics and also for stability analysis at different temperature and humidity conditions. Average particle size was found to be 21.40μm. Drug content of SLMs determined by HPLC analysis was found to be 98.6±0.31% while entrapment efficiency achieved was 98.02%. Drug release from the final formulation was found to be 90.3% in 90 min. SLMs formulated with glyceryl monostearate and sodium taurocholate can be used for oral delivery of hydrophobic drugs with in-vivo study still to be explored.

Solid Lipid Microparticles for the Stability Enhancement of a Dopamine Prodrug

The oral or peripheral administration of dopamine for the treatment of Parkinson's disease is hampered by its extensive metabolism and inability to cross the blood-brain barrier. Consequently, the enhancement of dopamine stability in physiologic environments and its brain targeting appear useful in formulation development. We propose the preparation and characterization of solid lipid microparticles based on tristearin as a sustained delivery system for dopamine. The microparticles were produced by conventional hot emulsion techniques. The synthesis of a new valeroyl ester of dopamine (3,4-O-divaleroyl-dopamine, DVD) was necessary to obtain its encapsulation in the microparticles. DVD appeared totally hydrolyzed to dopamine in human plasma within 40 s. The amount of encapsulated DVD in microparticles was 2.67 ± 1.2%. The mean diameter of particles was 14.2 ± 4.8 µm. The DVD release from microparticles was characterized by an initial burst of 20% of incorporated prodrug and a continuous slow release thereafter. The microparticles were able to stabilize DVD in its solid form. In human plasma, DVD encapsulated in microparticles hydrolyzed with a markedly reduced rate in comparison with free prodrug: after 15 min, 35.8% of DVD was still detectable. The DVD-loaded microparticles could represent a potential system for dopamine uptake in the brain, following nasal administration.