Stability Of Solid Lipid Nanoparticles Research Articles

Unraveling the Therapeutic Prospects of Solid Lipid Nanoparticles for the Treatment of Parasitic Diseases

Parasites induce a spectrum of illnesses, ranging from mild to severe, often causing significant global outbreaks. Existing antiparasitic drugs exhibit toxicity and notable side effects. Nanocarriers offer a promising solution by mitigating these issues through reduced side effects, enhanced target delivery, and additionally regulated prolonged active ingredient release. Solid lipid nanoparticles (SLNs), a subset of lipid nanoparticles (LNPs), have gained prominence for their favorable attributes. SLNs present themselves as a feasible option among colloidal carriers, offering an optimal release rate, stability, and precise target delivery. Their potential to deliver natural antiparasitic products is particularly noteworthy. Recent advancements in utilizing nanoparticles to enhance SLN stability and loading capacity are also explored in this review. The narrative encompasses SLN development, preparation methods, characterization, and the incorporation of drugs for combating parasitic diseases, offering insights into the evolving landscape of antiprotozoal SLN-saturated medications

Characterization and stability of solid lipid nanoparticles produced from different fully hydrogenated oils

The use of lipids from conventional oils and fats to produce solid lipid nanoparticles (SLN) attracting interest from the food industry, since due their varying compositions directly affects crystallization behavior, stability, and particle sizes (PS) of SLN. Thus, this study aimed evaluate the potential of fully hydrogenated oils (hardfats) with different hydrocarbon chain lengths to produce SLN using different emulsifiers. For that, fully hydrogenated palm kern (FHPkO), palm (FHPO), soybean (FHSO), microalgae (FHMO) and crambe (FHCO) oils were used. Span 60 (S60), soybean lecithin (SL), and whey protein isolate (WPI) were used as emulsifiers. The physicochemical characteristics and crystallization properties of SLN were evaluated during 60 days. Results indicates that the crystallization properties were more influenced by the hardfat used. SLN formulated with FHPkO was more unstable than the others, and hardfats FHPO, FHSO, FHMO, and FHCO exhibited the appropriate characteristics for use to produce SLN. Concerning emulsifiers, S60- based SLN showed high instability, despite the hardfat used. SL-based and WPI-based SLN formulations, showed a great stability, with crystallinity properties suitable for food incorporation.

Solid lipid nanoparticles cyclodextrin-decorated incorporated into gellan gum-based dry floating in situ delivery systems for controlled release of bioactive compounds of safflower (Carthamus tinctorius. L): A proof of concept study in biorelevant media

Safflower (Carthamus tinctorius L.) has been explored as a source of natural antioxidant. However, quercetin 7-O-beta-D-glucopyranoside and luteolin 7-O-beta-D-glucopyranoside, as its bioactive compounds, possessed poor aqueous solubility, limiting its efficacy. Here, we developed solid lipid nanoparticles (SLNs) decorated with hydroxypropyl beta-cyclodextrin (HPβCD) incorporated into dry floating gel in situ systems to control the release of both compounds. Using Geleol® as a lipid matrix, SLNs were <200 nm in size with >80 % of encapsulation efficiency. Importantly, following the decoration using HPβCD, the stability of SLNs in gastric environment was significantly improved. Furthermore, the solubility of both compounds was also enhanced. The incorporation of SLNs into gellan gum-based floating gel in situ provided desired flow and floating properties, with <30 s gelation time. The floating gel in situ system could control the release of bioactive compounds in FaSSGF (Fasted-State Simulated Gastric Fluid). Furthermore, to assess the effect of food intake on release behavior, we found that the formulation could show a sustained release pattern in FeSSGF (Fed-State Simulated Gastric Fluid) for 24 h after being released in FaSGGF for 2 h. This indicated that this combination approach could be a promising oral delivery for bioactive compounds in safflower.

Stabilization of solid lipid nanoparticles with glycyrrhizin

This study investigated the influence of saponin glycyrrhizin on the formation and stability of solid lipid nanoparticles. The hypothesis was that glycyrrhizin facilitates the formation of stable crystalline lipid particles due to its molecular characteristics and slows down polymorphic transition. Tristearin solid lipid nanoparticles emulsified with glycyrrhizin at varying concentrations at pH 7 and 3 were generated by hot high-pressure homogenization. The influence of glycyrrhizin on the physical stability and crystallization behavior of solid lipid nanoparticles was evaluated by dynamic and static lights scattering, electrophoretic light scattering, optical microscopy, visual observations, and differential scanning calorimetry. The results showed that glycyrrhizin formed nanosized solid lipid nanoparticles at both pH 7 and 3. The glycyrrhizin concentration and the pH applied governed the crystallization behavior and the polymorphic stability as well as the physical appearance. Overall, glycyrrhizin showed remarkable ability to stabilize solid lipid nanoparticles against polymorphic transition over time. These results are relevant for food, pharmaceutical, and cosmetic industries to form stable carrier systems by using natural plant-based saponins as surfactants.

Solid lipid nanoparticles for phytosterols delivery: The acyl chain number of the glyceride matrix affects the arrangement, stability, and release

The lipid matrix plays a key role in solid lipid nanoparticles (SLNs) embedding active ingredients. To investigate the influence of lipid matrix structure on arrangement, release, and stability of solid lipid nanoparticles, three phytosterols formulations with different carrier glycerides [glycerol monostearate (GMS), glycerol distearate (GDS), and glycerol tristearate (GTS)] were prepared and evaluated. X-ray diffraction and differential scanning calorimetry revealed the lowest crystallinity of phytosterols in the GMS matrix, corresponding to the maximum bioaccessibility (40.2%) in vitro experiments. Sustained release and better stability were observed from GDS and GTS matrices, which could be attributed to strong molecular interactions or a core-rich structure inside the nanoparticles. Molecular dynamics simulations demonstrated that the affinity between phytosterols and glycerides decreased in the order GDS > GTS > GMS, as well as explaining the release and storage capacities of the three nanoparticles. This study would facilitate the rational design of SLNs in functional foods.

Silymarin loaded solid lipid nanoparticles for oral delivery: Development, characterization and cytotoxic effect on breast cancer cells

The current study aimed to develop a silymarin (SM) loaded solid lipid nanoparticles (SLNs). Further, silymarin loaded solid lipid nanoparticles (SM-SLNs) were characterized for different quality parameters. The SLNs were prepared by temperature modulated solidification technique. The glyceryl monostearate (GMS) was selected as lipid, tween 80 as surfactant and mannitol as cryoprotectant. The SM-SLNs were characterized for particle size, polydispersity index (PDI), zeta potential (ZP), entrapment efficiency (EE), thermal behavior, and crystallinity. Further, the formulation was elucidated by MTT assay for cytotoxicity assessment. The particle size and PDI of the optimized formulation was found to be 178.6 ± 4.32 nm and 0.146, respectively. ZP (-36.4 mV) with a negative surface charge confirmed the physical stability of SLNs. Differential scanning calorimetry (DSC), X-ray diffraction (XRD) confirmed the transformation of lipid into SLNs through polymorphic transition of lipid crystallinity from β'-modification to α-modification and conversion of crystallinity of drug to amorphous state. The optimized formulation had an EE of 79.86%. The in-vitro drug release depicted a burst release for 1 h followed by fast release for 6 h and then sustained release over a duration of 24 h. SM-SLNs significantly reduced the growth of MCF-7 cells compared to silymarin. SM-SLNs exhibited small size in nanometer with narrow distribution, physically stable, and high entrapment efficiency. The developed nanoformulation could be used as a suitable drug delivery system for silymarin that has low water solubility, and a promising candidate for development of effective formulation in cancer therapy.

Solid lipid nanoparticles: Influence of composition, fabrication methods and problems, in vitro drug release and intranasal administration provide to access olfactory bulb pathway for SLNs

Background: Solid lipid nanoparticles (SLN) have drawn increasing interest in recent years. These nanoparticles are formed from stable or solid lipid mixtures and then stabilized by emulsifiers. As nanoparticles, colloidal particles running in size somewhere in the 10 to 1000 nm range are known. SLN provides fascinating properties, such as minimal scale, massive surface area, high medication piling, correspondence of stages at the interface, and is interested in their ability to enhance drug execution. Main text: This paper provides a description of the choice of ingredients, the effect of lipids and their structure on the formulation, and the various methods of processing SLN. We explain the characteristics of SLN stability and the possibilities of SLN stabilization by lyophilization in this article. The relation between drug absorption and the complexity of SLN dispersions, which involves the existence of other colloidal structures and the physical state of the lipid, is uncommonly considered. We define the possible problems of SLN preparation and performance on the basis of characterization. First, the nasal route was known to accomplish the avoidance of first-pass hepatic metabolism in order to maximize absolute bioavailability, and secondly, the immediate nose-to-brain pathway to enhance the delivery of brain medicines. SLNs have been designated to increase drug permeability through the blood-brain barrier as a drug delivery device (BBB). Conclusion: To sum up, this article gives insight SLNs a colloidal drug carrier places together the compensations of polymeric nanoparticles, SLNs have numerous benefits such as easy incorporation of lipid and lipophilic as well as hydrophilic drugs, suitable physical stability, and available at low cost and easy to manufacture. The nasal route was accepted to exploit first its prevention of the hepatic first-pass metabolism to increase the absolute bioavailability, and second, the direct nose-to-brain pathway to enhance the brain drug delivery. SLNs were chosen as a drug delivery system to improve drug permeability across the blood-brain barrier (BBB) and consequently its brain delivery.

Preparation, characterization, and physical stability of cocoa butter and tristearin nanoparticles containing \u03b2-carotene

Solid lipid nanoparticles (SLN) have emerged as a potential delivery system for bioactive ingredients, as they are associated with improving the stability of incorporated bioactive components by preventing their diffusion to the particle surface. The aim of this study was to investigate the impact of carrier lipid composition and surfactant type on the physical stability and thermal behavior of SLN containing β-carotene. As carrier lipids we used cocoa butter and/or tristearin and as surfactants we used Quillaja saponin extract in a combination with high- or low-melting lecithin. All the ingredients were food-grade. The results showed that all the SLN were physically stable and had a particle diameter < 200 nm, except for SLN containing only tristearin as carrier lipid and Quillaja saponins and low-melting lecithin as emulsifier, which showed slightly increased particle sizes during storage due to polymorphic transition. In general, this study indicated that the introduction of heterogenous lipids can improve the physical stability of the SLN due to the more random crystal structures formed. Moreover, the polymorphic stability is dependent on the surfactants applied. These results are of interest for manufacturers in food, pharmaceutical, cosmetic and personal care industries using cocoa butter or any lipid blend to enrich their products with bioactive components.

Heat Stability of Differently Stabilized Solid Lipid Nanoparticles in the Presence of Excess Bulk Phase Protein

In order to apply emulsion-based delivery systems to food, they have to be stable in a protein rich environment. This study investigated the stability of solid lipid nanoparticles (SLN) during heat treatment in the presence or absence of β-lactoglobulin (BLG). SLN were stabilized either by Tween 20 (TS) or by the protein itself (BS) and were enriched to a total BLG content of 56 mg/mL. The sizes of both types of SLN were initially in the range of 170 nm. The amount of free protein was determined before and after enrichment with BLG. As revealed by particle size and zeta potential measurements, a protein layer of BLG (hard corona) adsorbed on BS but not on TS. By contrast, a soft corona was formed around both BS and TS. SLN were heat treated in the presence and absence of protein and were characterized regarding size and zeta potential. According to transmission electron microscopy imaging, heating did not affect the shape of TS and BS: TS were platelets, whereas BS exhibited a spherical or platelet like shape. Upon heat treatment, the particle size of TS increased to about 3.5 fold of the initial size (to appr. 600 nm) in the presence and in the absence of excess protein. The cloudy protein layer (soft corona) around TS could thus not prevent coalescence of TS. By contrast, BS did not experience a change in particle size. Hence, by the choice of emulsifier, an encapsulation system that is stable against heat treatment can be obtained.

Enhanced storage stability of solid lipid nanoparticles by surface modification of comb-shaped amphiphilic inulin derivatives

Solid lipid nanoparticles (SLNs) have been widely used as a vehicle for drug delivery. However, highly ordered lipid lattices and poor storage stability limit their practical application. Highly ordered crystal lattices may result from the low drug payload. In addition, the lipid matrix of SLNs may undergo a polymorphic transition from high energy and disordered modifications to low energy and ordered modifications during storage. This leads to drug expulsion and precipitation. Meanwhile, SLNs are susceptible to particle aggregation and size growth during storage. To improve the performance of SLNs, two comb-shaped amphiphilic macromolecular materials (CAMs), dodecyl inulin (Inu12) and octadecyl inulin (Inu18), were synthesized and utilized as emulsifiers to modify and stabilize SLNs (Inu12/Inu18-SLNs). The results indicated that Inu12 and Inu18 could more effectively reduce the lipid crystallinity and crystal lattice order of fresh SLNs versus Poloxamer 188 and Tween-80. Moreover, after six months of storage at 4 °C or 25 °C, both blank and Cyclosporine A (CsA)-loaded Inu12/Inu18-SLNs had a slower crystal transition than Tween/P188-SLNs. The particle size increases of Inu12/Inu18-SLNs were much smaller than those of Tween/P188-SLNs. The drug encapsulation efficiencies of CsA-loaded Inu12/Inu18-SLNs during storage decreased more slowly than Tween-SLNs. Therefore, Inu12 and Inu18 could more effectively inhibit lipid crystal transition and prevent particle aggregation during storage. This, in turn, leads to better storage physical stability of SLNs. Thus, the Inu12 and Inu18 CAMs were superior to Tween-80 and Poloxamer 188 (common straight-chain surfactants).

99mTc(I) carbonyl-radiolabeled lipid based drug carriers for temozolomide delivery and bioevaluation by in vitro and in vivo

Abstract In preclinical research radiolabeled nanoparticles have been attracting interest as a new class of imaging probes. Assuming good stability of solid lipid nanoparticles (SLNs) under physiological conditions, radiolabeled SLNs can be used for imaging and measuring uptake in target tissue. Present study was performed to evaluate biological behavior of temozolomide (TMZ) loaded solid lipid nanoparticles (SLN-TMZ) in vivo and in vitro. Lipid nanoparticles were prepared by emulsification and low-temperature solidification method. ζ potential, morphology and particle size of nanoparticles were determined. Biological behavior of 99mTc(CO)3 + radiolabeled SLN-TMZ were investigated in vitro on U87/Daoy cell lines and in vivo on female Wistar Albino rats. Obtained results of in vitro incorporation, in vivo biodistribution and gamma imaging studies on radiolabeled SLN-TMZ show that the radiolabeled solid lipid nanoparticles could have potential as a drug delivery system for TMZ.

Solid lipid nanoparticles modified with amphipathic chitosan derivatives for improved stability in the gastrointestinal tract

In order to reduce enzymatic degradation and thereby improve the stability of solid lipid nanoparticles (SLNs) in the gastrointestinal tract (GIT), two comb-shaped amphiphilic macromolecular materials of N-stearyl-N-trimethyl chitosan (STMC) and N-linoleoyl-N-trimethyl chitosan (LTMC) were fabricated as emulsifier to modify SLNs. Some influence factors of lipolysis medium were investigated to establish in vitro lipolysis model for SLNs. The results showed that the lipolysis curves were fluctuant and variable when the amounts of SLNs were low. The lipolysis of SLNs increased with pancreatic enzyme activity ascending from 150 to 450 USPU/mL and achieved a threshold between 450 and 600 USPU/mL. The lipolysis of STMC-SLNs increased with the initial calcium concentration rising from 0 to 1.4 mM, but had no obvious change from 1.4 to 5 and 10 mM. Besides, SLNs lipolysis increased with bile acid salt and phospholipid concentration increasing. Finally, SLNs stability in GIT was tested with the optimized in vitro lipolysis model. The results revealed that as compared to P188-SLNs and Tween-SLNs, STMC-SLNs lipolysis decreased by 27.33% and 48.55%, and LTMC-SLNs decreased by 22.64% and 43.86%, respectively. Besides, the drug precipitations for STMC-SLNs and LTMC-SLNs were significantly decreased. These results demonstrated that both STMC-SLNs and LTMC-SLNs had excellent gastrointestinal stability.

Nebulized solid lipid nanoparticles for the potential treatment of pulmonary hypertension via targeted delivery of phosphodiesterase-5-inhibitor

Phosphodiesterase type 5 (PDE-5) inhibitors – among which sildenafil citrate (SC) – play a primary role in the treatment of pulmonary hypertension (PH). Yet, SC can be only administered orally or parenterally with lot of risks. Targeted delivery of SC to the lungs via inhalation/nebulization is mandatory. In this study, solid lipid nanoparticles (SLNs) loaded with SC were prepared and characterized in terms of colloidal, morphological and thermal properties. The amount of drug loaded and its release behavior were estimated as a function of formulation variables. The potential of lipid nanocarriers to retain their properties following nebulization and autoclaving was investigated. In addition, toxicity aspects of plain and loaded SLNs on A549 cells were studied with respect to concentration. Spherical SLNs in the size range (100–250nm) were obtained. Particles ensured high encapsulation efficiency (88–100%) and sustained release of the payload over 24h. Cell-based viability experiments revealed a concentration-dependant toxicity for both plain and loaded SLNs recording an IC50 of 516 and 384μg/mL, respectively. Nebulization with jet nebulizer and sterilization via autoclaving affected neither the colloidal stability of SLNs nor the drug entrapment, proving their potential as pulmonary delivery system. Interaction of SLNs with mucin was a function of the emulsifier coating layer. Results yet seeking clinical evidence – might give promises of new therapy for PH of higher safety, better performance and higher patient compliance.

Technological stability of solid lipid nanoparticles loaded with phenolic compounds: Drying process and stability along storage

Solid lipid nanoparticles (SLNs) have been widely studied and tested as vehicles for natural compounds. Recently, Witepsol and Carnauba SLNs were shown to be effective systems for the entrapment of rosmarinic acid (RA) and herbal extracts. In the present work, the improvement of stability and bioactivity of these systems was studied. Thus, the freeze-drying of SLNs produced with Witepsol and Carnauba waxes loaded with RA and herbal extracts (sage and savory) were tested. The use of three different cryoprotectants (glucose, mannitol and trehalose) at two different concentrations (5 and 10%, w/v) were evaluated. Furthermore, the prepared SLNs were stored under different conditions (atmosphere, temperature, absence or presence of light) and in different packaging materials, over 365 days. The effect on the SLNs physical stability and bioactivity was assessed. The most suitable cryoprotectant was mannitol at 10% (w/v) for all formulations tested. The solid state of SLNs, with storage at room temperature, in glass flasks, protected from light and under N2 controlled atmosphere were the best storage conditions in which the SLNs bioactivity was maintained during 365 days.

Development of Gel-Core Solid Lipid Nanoparticles as Drug Delivery Systems for Hydrophilic Molecules

Background: We report the development and characterization of gelcore solid lipid nanoparticles (SLN) for the encapsulation of hydrophilic proteins, taking bovine serum albumin (BSA) as model compound. Methods: SLN were produced by multiple emulsion (w/o/w) method, while hydrogels were produced by dissolving Carbopol 971 in purified water under high-speed stirring. Physicochemical characterization followed the pH determination, fluorescence and scanning electron microscopy analyses, and the quantification of the drugs by spectrophotometric measurements (for the determination of encapsulation efficiency and release profile). Results: The stability of SLN was found to be dependent on the type of nanoparticle core. Gel-core SLN were more stable than aqueous-core SLN, both during production and during shelf life. It has been shown that an increase in the core volume is possible for gel-core SLN during their preparation. The hydrodynamic diameter of gelcore SLN formulated in the absence and presence of Bovine serum albumin was ca. 200 nm. To determine the encapsulation efficiency (EE) and in vitro release profile, two model compounds, i.e. hydrophilic dye (Methylene blue) and fluorescent probe (Rhodamine B) have been used. It has been shown that EE depends on the type of nanoparticles. EE of the Rhodamine B-loaded SLN was recorded between 80-90%, for both gel-core and aqueous-core SLN. The release of Rhodamine D from gel-core SLN was slower than that from aqueous-core SLN. The release profile was shown to be dependent on the swelling of the core of SLN. Conclusion: The optimized SLN formulation proposed in this study (with the internal gel phase composed of 0.2% Carbopol 971) was found to be more stable over time, depicting lower polydispersity index and slower release, than the aqueouscore SLN. Keywords: Bovine serum albumin, drug delivery systems, hydrogels, hydrophilic biomolecules, methylene blue, rhodamine B, solid lipid nanoparticles.

Formation and stability of solid lipid nanoparticles fabricated using phase inversion temperature method

Abstract 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, C12E4)/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.

Effect of liquid-to-solid lipid ratio on characterizations of flurbiprofen-loaded solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) for transdermal administration

The aim of this study is to evaluate the effect of liquid-to-solid lipid ratio on properties of flurbiprofen-loaded solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs), and to clarify the superiority of NLCs over SLNs for transdermal administration. Particle size, zeta potential, drug encapsulation efficiency, in vitro occlusion factor, differential scanning calorimetry, X-ray diffractometry, in vitro percutaneous permeation profile, and stability of SLNs and NLCs were compared. Particle size, zeta potential, drug encapsulation efficiency, in vitro occlusion factor, and in vitro percutaneous permeation amount of the developed NLCs were all <200 nm, < −20 mV, >78%, >35, and >240 μg/cm2, respectively, however, for SLNs were 280 nm, −29.11 mV, 63.2%, 32.54, and 225.9 μg/cm2, respectively. After 3 months storage at 4 °C and 25 °C, almost no significant differences between the evaluated parameters of NLCs were observed. However, for SLNs, particle size was increased to higher than 300 nm (4 °C and 25 °C), drug encapsulation efficiency was decreased to 51.2 (25 °C), in vitro occlusion factor was also decreased to lower than 25 (4 °C and 25 °C), and the cumulative amount was decreased to 148.9 μg/cm2 (25 °C) and 184.4 μg/cm2 (4 °C), respectively. And DSC and XRD studies indicated that not only the crystalline peaks of the encapsulated flurbiprofen disappeared but also obvious difference between samples and bulk Compritol® ATO 888 was seen. It could be concluded that liquid-to-solid lipid ratio has significant impact on the properties of SLNs and NLCs, and NLCs showed better stability than SLNs. Therefore, NLCs might be a better option than SLNs for transdermal administration.

The Entrapment of Vitamin E in Nanostructured Lipid Carriers of Rambutan Seed Fat for Cosmeceutical Uses

The aim of the present work was to extract the seed fat of Rambutan (Nephelium lappaceum L.) for developing nanostructured lipid carriers. Effect of material: solvent ratio and material size time on fat content were investigated. Nanostructured lipid carriers were prepared by melt-emulsification technique. Stearic acid (SA) and the rambutan seed fat (RF) was used as solid and liquid lipid, respectively. Surfactant was Tween 20 as well as Vitamin E was entrapment chemical. Effect of surfactant concentration on formation and stability of solid lipid nanoparticles (SLN) was investigated. At higher surfactant concentrations, NLC had smaller particle size and better stability of nanoparticles. At the optimal concentration of Tween 20 (5% w/w), NLC had a mean particle diameter of 139.43 ± 1.15 nm and a polydispersity index of 0.165 ± 0.017. Zeta potential was above 30 mV.

Freeze-drying of ampicillin solid lipid nanoparticles using mannitol as cryoprotectant

abstract Solid lipid nanoparticles (SLNs) are interesting colloidal drug-delivery systems, since they have all the advantages of the lipid and polymeric nanoparticles. Freeze-drying is a widely used process for improving the stability of SLNs. Cryoprotectants have been used to decrease SLN aggregations during freeze-drying. In this study Ampicillin was chosen to be loaded in a cholesterol carrier with nano size range. To support the stability of SLNs, freeze-drying was done using mannitol. Particle size, drug release profile and antibacterial effects were studied after freeze-drying in comparison with primary SLNs. Preparations with 5% mannitol showed the least particle size enlargement. The average particle size was 150 and 187 nm before and after freeze-drying, respectively. Freeze-drying did not affect the release profile of drug loaded nanopartilces. Also our study showed that lyophilization did not change the antimicrobial effect of ampicillin SLNs. DSC analysis showed probability of chemical interaction between ampicillin and cholesterol.

Solid lipid nanoparticles for oral drug delivery: Chitosan coating improves stability, controlled delivery, mucoadhesion and cellular uptake

The poor stability of solid lipid nanoparticles (SLN) under acidic condition resulted in large aggregation in gastric environment, limiting their application as oral delivery systems. In this study, a series of SLN was prepared to investigate the effects of surfactant/cosurfactant and chitosan coating on their physicochemical properties as well as cellular uptake. SLN was prepared from Compritol 888 ATO using a low-energy method combining the solvent-diffusion and hot homogenization technique. Poloxamer 188 and polyethylene glycol (PEG) were effective emulsifiers to produce SLN with better physicochemical properties than SLN control. Chitosan-coated SLN exhibited the best stability under acidic condition by forming a thick layer around the lipid core, as clearly observed by transmission electron microscope. The intermolecular interactions in different formulations were monitored by Fourier transform infrared spectroscopy. Chitosan coating also significantly improved the mucoadhesive property of SLN as determined by Quartz Crystal Microbalance. In vitro drug delivery assays, cytotoxicity, and cellular uptake of SLN were studied by incorporating coumarin 6 as a fluorescence probe. Overall, chitosan-coated SLN was superior to other formulations and held promising features for its application as a potential oral drug delivery system for hydrophobic drugs.