Name: self-nanoemulsification of healthy oils to enhance the solubility of lipophilic drugs
Uploaded: 2022-07-27T14:00:00.000+00:00
Duration: 8 min 18 s
Description: Watch this Scientific Journal Video about Self-Nanoemulsification of Healthy Oils to Enhance the Solubility of Lipophilic Drugs at JoVE.com

Authors acknowledges the Department of Pharmacy, Quaid-i-Azam University, Islamabad, Pakistan for providing the necessary facilities to complete this study.

1. Screening of the oils, surfactants, and cosurfactants
<ol>
	<li>Screening of the oils, surfactants, and co-surfactants for drug solubility
	<ol>
		<li>Mix 100 mg of rosuvastatin separately in 1 mL of different omega-3 fatty acids-rich oils (fish oil, olive oil, sesame oil, and linseed oil) and 1 mL of surfactants and cosurfactants (Tween 80, Capryol PGMC, PEG 400, and ethanol) by vortexing for 5 min at a fixed-speed of 2,500 rpm. Then, place in a shaking water bath for 48 h at 50 &#176;C.</li>
		<li>After shaking, let the mixture settle for at least 6 h at room temperature so that the undissolved drug is precipitated. Take 0.1 mL of supernatant by using a micropipette and dilute up to 1 mL with methanol.</li>
		<li>Analyze by using a UV-visible spectrophotometer at 242 nm and calculate the concentration by adding the absorption to the straight-line equation of the calibration curve19,20. 
		NOTE: Establish the calibration curve by preparing a stock solution of 100 &#181;g/mL and making serial dilutions up to 0.5 &#181;g/mL. Absorbance is taken for all dilutions and a graph is plotted between absorbance and concentration in a spreadsheet. The straight-line equation (y = mx + b) of the graph is rearranged so that value of absorbance (y) can be used to calculate the unknown concentration (x)19,20.</li>
	</ol>
	</li>
	<li>Screening of the surfactant and co-surfactants for miscibility with oil
	<ol>
		<li>Mix the surfactant and the co-surfactant (Smix) in a 3:1 ratio. Add Smix and oil in different ratios; mix and heat up to 50 &#176;C to ensure homogenization.</li>
		<li>Take 0.1 mL from each mixture and dilute with 25 mL of distilled water in a glass test tube.</li>
		<li>Invert the test tube; the number of inversions at which an emulsion is formed represents the emulsification efficacy and ease of emulsification. Measure the transparency (T%) by measuring the emulsion at 650 nm with a UV-visible spectrophotometer using distilled water as a blank21.</li>
	</ol>
	</li>
</ol>
2. Construction of the pseudo ternary phase diagram
<ol>
	<li>Mix the surfactants and the co-surfactants in various volume ratios (1:0, 1:1, 1:2, 1:3,1:4, and 1:5) to form surfactant mixtures (Smix). Add oil to the Smix in separate vials at various volume ratios of 1:1,1:2,1:3,1:4,1:5,1:6,1:7, 1:8, 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, and 9:1, and mix by vortexing.</li>
	<li>Add oil and Smix mixtures in a 10 mL glass vial and heat up to 50 &#176;C with constant stirring at 300 rpm for optimal mixing.</li>
	<li>Cool the mixture to 37 &#176;C and transfer 1 mL from it to a 250 mL water beaker and add dropwise the preheated distilled water (37 &#176;C) under gentle stirring at 50 rpm. Examine the dispersion visually and the mixture that forms a bluish transparent nanoemulsion is regarded as SNEDDS21.</li>
	<li>Construct the pseudoternary plot at different Smix ratios (Supplementary Table 1) through software (e.g., Triplot).</li>
</ol>
3. Optimization via software using a response surface methodology (RSM)
<ol>
	<li>Select three independent variables as oil (A), surfactant (B) and co-surfactant, and run the software for optimization and screening. Then, select the flexible design by choosing &#39;NO&#39; to a hard-to-change selection.
	<ol>
		<li>Observe the effect of these factors critically on dependent variables such as particle size (Y1, nm), zeta potential (Y2, mV), emulsification time (Y3, s) as well as entrapment efficiency (Y4, %) as mentioned in Table 2. 
		NOTE: The runs were increased until the warning signs disappeared and the software itself selected the Box-Benhken design for optimization.</li>
	</ol>
	</li>
	<li>Select the higher and lower values as -1 identifying the lowest variable value, whereas +1 depicts the highest value. The mid-value depicted the middle value. Box-Benhken design suggested a total of 17 runs with five center points as a measure to reduce the error.</li>
	<li>Record the responses to individual runs and fit to linear, 2F1, and quadratic models to ensure the best-fitted model. Generate polynomial equations and utilize to make the inference on the basis of the magnitude of the coefficient corresponding numerical signs.</li>
	<li>Display data of polynomial regression as 3-D plots. Evaluate the best fitted data model by comparing adjusted R2 and predicted R2 value 22. 
	NOTE: The required selection criteria of the formulation was based on grounds of maximum entrapment efficiency, less particle size, higher zeta potential, and minimum emulsification time frame. 
	Y = &#946;0 + &#946;1A + &#946;2B + &#946;3C + &#946;12AB + &#946;13AC + &#946;23BC + &#946;11A2 + &#946;22B2 + &#946;33C2 Eq. (1) 
	Here, &#946;0 appeared as intercept, Y as a response, ad &#946;1, &#946;2, and &#946;3 as linear coefficients. &#914;11, &#946;22, and &#946;33 as quadratic terms and squared coefficients while &#946;12, &#946;13, and &#946;23 as interaction coefficients. A, B, and C employed as independent variables that were selected from results of preliminary study.</li>
</ol>
4. Characterization
<ol>
	<li>Thermodynamic stability studies
	<ol>
		<li>Store the diluted SNEDDS at 4 &#176;C in a refrigerator, and then transfer it to a 50 &#176;C incubator . Perform six such cycles, each cycle being equal to or greater than 48 h.</li>
		<li>Examine the formulation for phase separation23.</li>
	</ol>
	</li>
	<li>Centrifugation test
	<ol>
		<li>Centrifuge the diluted SNEDDS for 30 min at 3,500 rpm at -4 &#176;C.</li>
		<li>Examine the SNEDDS at room temperature for phase separation or sedimentation of drug24.</li>
	</ol>
	</li>
	<li>Dispersibility test for self-emulsification efficacy
	<ol>
		<li>Add 1 mL of the formulation dropwise to 500 mL of double distilled water maintained at 37 &#176;C and 50 rpm. Note the time in which a clear homogenous emulsion is formed by visual inspection.</li>
		<li>Perform a visual assessment according to the following grading system25. 
		Grade 1: a clear bluish emulsion with emulsification time &#60;1 min 
		Grade 2: a bluish-white emulsion with emulsification time &#60;1 min 
		Grade 3: milky appearance with emulsification time &#60;2 min 
		Grade 4: gray, white appearance oil on top with emulsification time &#62;2 min 
		Grade 5: emulsification failure with larger oil droplet on top. 
		NOTE: The time required for emulsification or rate of emulsification is vital to emulsification efficacy. The test is performed in a USP type II dissolution apparatus.</li>
	</ol>
	</li>
	<li>Robustness to dilutions
	<ol>
		<li>Dilute the optimized SNEDDS formulation 50, 100, and 1,000 times with different carriers such as distilled water, 0.1 N HCl (pH 1.0) to mimic gastric pH and phosphate buffer (pH 6.8) to mimic intestinal pH.</li>
		<li>Thoroughly mix the diluted mixtures and set them aside for 12 h.</li>
		<li>Visually examine the formulations for drug precipitation, phase separation, and any other stability issue26,27.</li>
	</ol>
	</li>
</ol>
5. In vitro dissolution studies
<ol>
	<li>Perform the release of drug from SNEDDS and pure drug suspension by using a water shaking bath maintained at 37 &#176;C and 50 rpm.</li>
	<li>Soak the dialysis membranes in the respective media solution for 24 h before the drug dissolution assay to attain good integrity and activation. Fill the drug suspension (in water) and SNEDDS equivalent to 10 mg of rosuvastatin in the dialysis membrane; tie and place in separate beakers (50 mL).</li>
	<li>Take 1 mL of the sample at specific intervals and replenish the beaker with fresh media (1 mL) after each sample.</li>
	<li>Filter the drawn samples and analyze by using a UV-visible spectrophotometer at 242 nm21,28,29,30.</li>
</ol>

The authors have nothing to disclose.

This study was designed to explore the potential of omega-3 fatty acids-rich oil, such as fish oil, sesame oil, olive oil, and linseed oil to act as drug carriers. Self-nanoemulsification was selected as a preferred technique for fabricating the delivery system that lacks water, making it more stable than classical emulsion systems32. Omega-3 fatty acids-rich oils are known for their beneficial health effects18. They have been used as a supplement for various diseases such ...

Lipids have been used for centuries to increase gastrointestinal absorption of water insoluble components of food and medicines1. Emulsions are the formulations used most widely for oral, intravenous (nutritional supplementation), and topical use2. A variety of lipids (fats and oils) are used in the manufacturing of pharmaceutical emulsions and lipid-based self-nanoemulsifying drug delivery systems (SNEDDS). Self-emulsification techniques are widely adopted in pharmaceutical sciences for transmucosal drug delivery. Unlike emulsions, SNEDDS consist of an oil and a surfactant mixture that self-emulsifies in an aqueous medium of the stomach to form emulsion droplets3. They can load lipophilic drugs in the oil phase and prevent them from degrading in the stomach environment4. SNEDDS have been shown to effectively enhance the bioavailable fraction of lipophilic drugs (four to six folds) by enhancing solubility and permeability5,6. The absence of an aqueous phase in SNEDDS offers significant advantages in terms of ease of manufacture and stability as compared to emulsions that are metastable dispersions prone to chemical degradation7. Many lipid excipient combinations are commercially available due to their desirable characteristics8,9.
Cardiovascular disorders are a leading cause of mortality worldwide10 and, hyperlipidemia causes the blood vessels to obstruct blood flow due to thickening of the blood vessels11. Increased dietary lipid uptake and a sedentary lifestyle are the major risk factors for development of hyperlipidemia. In addition to this, lipids have also been shown to directly damage the myocardium of the heart leading to non-ischemic heart failure12. Rosuvastatin is a potent hypolipidemic drug that belongs to the statin class and inhibits cholesterol synthesis leading to the lowering of lipid levels for the treatment of hyperlipidemia/dyslipidemia13. Rosuvastatin is a biopharmaceutical classification system (BCS) class II with poor aqueous solubility (0.01796 mg/mL)14. Recent advances in pharmaceutical research have recognized that lipids used in drug delivery can disturb the lipid profile of patients. The role of emulsions to increase low- and high-density lipoproteins and free cholesterol was demonstrated in the late twentieth century15. In addition to this, lipid-based drug delivery systems have shown to increase triglycerides16 and other lipid metabolites in the blood17. Therefore, there is a dire need to develop pharmaceutical formulations of oils that are unable to disturb the lipid profile of cardiovascular and hyperlipidemic patients.
Fish oil is a rich source of omega-3 fatty acids such as eicosapentaenoic acid and docosahexaenoic acid. Fish oil has shown many health effects with substantial evidence of its beneficial role in cardiovascular and nervous systems18. The aim of the study was to utilize fish oil as an alternative to the conventional oils to formulate SNEDDS for the delivery of a lipophilic drug, rosuvastatin. No previous study has employed fish oil as a carrier to formulate drug delivery systems. Appropriate formulation and processing parameters were selected, and optimization was performed using design expert software.

<table><tbody><tr><td>Ammonium acetate</td><td>Sigma-Aldrich, Germany</td><td>A1542</td><td>Analytical grade</td></tr><tr><td>Capryol PGMC</td><td>Gattefoss&amp;eacute;, France</td><td>RT9P9S09QI</td><td>Analytical grade</td></tr><tr><td>Design Expert Software</td><td>StatEase, United States</td><td>Version 12.0.3.0</td><td>Analytical software (freely available for subscription)</td></tr><tr><td>Dialysis tubing (12,000 Daltons MWCO)</td><td>Visking, UK</td><td>12000.02.30</td><td>Pure regenerated natural cellulose membranes with 12,000 Daltons MWCO</td></tr><tr><td>Dissolution apparatus</td><td>Memmert, Germany</td><td>SV 1422</td><td>USP type II dissolution apparatus</td></tr><tr><td>Ethanol</td><td>Honeywell, Germany</td><td>24194</td><td>Analytical grade</td></tr><tr><td>Fish oil</td><td>Wilshire Labs Pvt(Ltd), Pakistan</td><td>not applicable</td><td>Received as gift sample.</td></tr><tr><td>Hydrochloric acid</td><td>BDH Laboratories Ltd, UK</td><td>BDH3036-54L</td><td>Analytical grade</td></tr><tr><td>Methanol</td><td>Honeywell, Germany</td><td>34966</td><td>Analytical grade</td></tr><tr><td>Refrigerator (Pharmaceutical)</td><td>Panasonic, Pakistan</td><td>MPR-161 DH-PE</td><td>Refrigerator for storage at 4 &amp;deg;C</td></tr><tr><td>Rosuvastatin calcium</td><td>Searle Pharmaceuticals Pvt(Ltd) Pakistan</td><td>not applicable</td><td>Received as gift sample.</td></tr><tr><td>Sodium Hydroxide</td><td>Honeywell, Germany</td><td>38215</td><td>Analytical grade</td></tr><tr><td>Span 80</td><td>BDH Laboratories Ltd, UK</td><td>MFCD00082107</td><td>Analytical grade</td></tr><tr><td>Triplot Software</td><td>MS Excel spreadsheet developed by Tod Thompson</td><td>Triplot Ver. 4.1.2</td><td>Analytical software (freely available)</td></tr><tr><td>Tween-80</td><td>Sigma-Aldrich, Germany</td><td>P1754-500ML</td><td>Analytical grade</td></tr><tr><td>UV-Vis spectrophotometer</td><td>Dynamica, UK</td><td>Halo DB-20</td><td>Double beam spectrophotometer</td></tr><tr><td>Water Bath</td><td>Memmert, Germany</td><td>WNB 7</td><td>Water batch for heating up to 70 &amp;deg;C</td></tr></tbody></table>

self-nanoemulsification of healthy oils to enhance the solubility of lipophilic drugs

The low aqueous solubility of many drugs reduces their bioavailability in the blood. Oils have been used for centuries to enhance the solubility of drugs; however, they can disturb the lipid profile of the patients. In this study, self-nanoemulsifying drug delivery systems of omega-3 fatty acids-rich oils are prepared and optimized for the delivery of lipophilic drugs. Rosuvastatin, a potent hypolipidemic drug, was used as a model lipophilic drug. Fish oil showed more than 7-fold higher solubility of rosuvastatin than other oils and therefore it was selected for the development of self-nanoemulsifying drug delivery systems (SNEDDS). Different combinations of surfactants and co-surfactants were screened and a surfactant mixture of Tween 80 (surfactant) and Capryol PGMC (cosurfactant) were selected for compatibility with fish oil and rosuvastatin. A pseudoternary phase diagram of oil, surfactant, and co-surfactant was designed to identify the emulsion region. The pseudoternary phase diagram predicted a 1:3 oil and surfactant mixture as the most stable ratio for the emulsion system. Then, a response-surface methodology (Box-Behnken design) was applied to calculate the optimal composition. After 17 runs, fish oil, Tween 80, and Capryol PGMC in proportions of 0.399, 0.67, and 0.17, respectively, were selected as the optimized formulation. The self-nanoemulsifying drug delivery systems showed excellent emulsification potential, robustness, stability, and drug release characteristics. In the drug release studies, SNEDDS released 100% of the payload in around 6 h whereas, release of the plain drug was less than 70% even after 12 h. Therefore, omega-3 fatty acids-rich healthy lipids have enormous potential to enhance the solubility of lipophilic drugs whereas, self-emulsification can be used as a simple and feasible approach to exploit this potential.

Herein, nanoformulation of omega-3 fatty acids-rich fish oil are prepared and optimized by self-emulsification with different surfactants and co-surfactants. Figure 1 shows the solubility of rosuvastatin in different oils, surfactants, and co-surfactants. Based on solubility, fish oil was selected as the oil, Tween 80 as the surfactant, and Capryol PGMC as the co-surfactant in the following studies. Table 1 shows the screening of Smix at different ratios to emulsify fish oil...

Watch this Scientific Journal Video about Self-Nanoemulsification of Healthy Oils to Enhance the Solubility of Lipophilic Drugs at JoVE.com

Self-Nanoemulsification of Healthy Oils to Enhance the Solubility of Lipophilic Drugs

Oils used for drug delivery applications can disrupt the lipid profile of patients, which is undesirable in cardiovascular diseases. Omega-3 fatty acids-rich oils are a healthy alternative to conventional oils and have enormous potential for self-emulsified drug delivery systems.

The low aqueous solubility of many drugs reduces their bioavailability in the blood. Oils have been used for centuries to enhance the solubility of drugs; ...

self-nanoemulsification-healthy-oils-to-enhance-solubility-lipophilic

Research

JoVE Journal

Biology

985 Views.  Quaid-i-Azam University. Oils used for drug delivery applications can disrupt the lipid profile of patients, which is undesirable in cardiovascular diseases. Omega-3 fatty acids-rich oils are a healthy alternative to conventional oils and have enormous potential for self-emulsified drug delivery systems.

Video: Self-Nanoemulsification of Healthy Oils to Enhance the Solubility of Lipophilic Drugs

Synthesis of Phase-shift Nanoemulsions with Narrow Size Distributions for Acoustic Droplet Vaporization and Bubble-enhanced Ultrasound-mediated Ablation

High-intensity focused ultrasound (HIFU) is used clinically to thermally ablate tumors. To enhance localized heating and improve thermal ablation in tumors, lipid-coated perfluorocarbon droplets have been developed which can be vaporized by HIFU. The vasculature in many tumors is abnormally leaky due to their rapid growth, and nanoparticles are able to penetrate the fenestrations and passively accumulate within tumors. Thus, controlling the size of the droplets can result in better accumulation within tumors. In this report, the preparation of stable droplets in a phase-shift nanoemulsion (PSNE) with a narrow size distribution is described. PSNE were synthesized by sonicating a lipid solution in the presence of liquid perfluorocarbon. A narrow size distribution was obtained by extruding the PSNE multiple times using filters with pore sizes of 100 or 200 nm. The size distribution was measured over a 7-day period using dynamic light scattering. Polyacrylamide hydrogels containing PSNE were prepared for in vitro experiments. PSNE droplets in the hydrogels were vaporized with ultrasound and the resulting bubbles enhanced localized heating. Vaporized PSNE enables more rapid heating and also reduces the ultrasound intensity needed for thermal ablation. Thus, PSNE is expected to enhance thermal ablation in tumors, potentially improving therapeutic outcomes of HIFU-mediated thermal ablation treatments.

Phase-shift nanoemulsions (PSNE) can be vaporized using high intensity focused ultrasound to enhance localized heating and improve thermal ablation in tumors. In this report, the preparation of stable PSNE with a narrow size distribution is described. Furthermore, the impact of vaporized PSNE on ultrasound-mediated ablation is demonstrated in tissue-mimicking phantoms.

High-intensity  focused ultrasound (HIFU) is used clinically to thermally ablate tumors. To  enhance localized heating and improve thermal ablation in ...

Engineering

Facile Preparation of Internally Self-assembled Lipid Particles Stabilized by Carbon Nanotubes

We present a facile method to prepare nanostructured lipid particles stabilized by carbon nanotubes (CNTs). Single-walled (pristine) and multi-walled (functionalized) CNTs are used as stabilizers to produce Pickering type oil-in-water (O/W) emulsions. Lipids namely, Dimodan U and Phytantriol are used as emulsifiers, which in excess water self-assemble into the bicontinuous cubic Pn3m phase. This highly viscous phase is fragmented into smaller particles using a probe ultrasonicator in presence of conventional surfactant stabilizers or CNTs as done here. Initially, the CNTs (powder form) are dispersed in water followed by further ultrasonication with the molten lipid to form the final emulsion. During this process the CNTs get coated with lipid molecules, which in turn are presumed to surround the lipid droplets to form a particulate emulsion that is stable for months. The average size of CNT-stabilized nanostructured lipid particles is in the submicron range, which compares well with the particles stabilized using conventional surfactants. Small angle X-ray scattering data confirms the retention of the original Pn3m cubic phase in the CNT-stabilized lipid dispersions as compared to the pure lipid phase (bulk state). Blue shift and lowering of the intensities in characteristic G and G&#39; bands of CNTs observed in Raman spectroscopy characterize the interaction between CNT surface and lipid molecules. These results suggest that the interactions between the CNTs and lipids are responsible for their mutual stabilization in aqueous solutions. As the concentrations of CNTs employed for stabilization are very low and lipid molecules are able to functionalize the CNTs, the toxicity of CNTs is expected to be insignificant while their biocompatibility is greatly enhanced. Hence the present approach finds a great potential in various biomedical applications, for instance, for developing hybrid nanocarrier systems for the delivery of multiple functional molecules as in combination therapy or polytherapy.

We report on a smart application of carbon nanotubes for kinetic stabilization of lipid particles that contain self-assembled nanostructures in their cores. The preparation of lipid particles requires rather low concentrations of carbon nanotubes permitting their use in biomedical applications such as drug delivery.

We present a facile method to prepare nanostructured lipid particles stabilized by carbon nanotubes (CNTs). Single-walled (pristine) and multi-walled ...

Chemistry

Constant Pressure-controlled Extrusion Method for the Preparation of Nano-sized Lipid Vesicles

Liposomes are artificially prepared vesicles consisting of natural and synthetic phospholipids that are widely used as a cell membrane mimicking platform to study protein-protein and protein-lipid interactions3, monitor drug delivery4,5, and encapsulation4. Phospholipids naturally create curved lipid bilayers, distinguishing itself from a micelle.6 Liposomes are traditionally classified by size and number of bilayers, i.e. large unilamellar vesicles (LUVs), small unilamellar vesicles (SUVs) and multilamellar vesicles (MLVs)7. In particular, the preparation of homogeneous liposomes of various sizes is important for studying membrane curvature that plays a vital role in cell signaling, endo- and exocytosis, membrane fusion, and protein trafficking8. Several groups analyze how proteins are used to modulate processes that involve membrane curvature and thus prepare liposomes of diameters &lt;100 - 400 nm to study their behavior on cell functions3. Others focus on liposome-drug encapsulation, studying liposomes as vehicles to carry and deliver a drug of interest9. Drug encapsulation can be achieved as reported during liposome formation9. Our extrusion step should not affect the encapsulated drug for two reasons, i.e. (1) drug encapsulation should be achieved prior to this step and (2) liposomes should retain their natural biophysical stability, securely carrying the drug in the aqueous core. These research goals further suggest the need for an optimized method to design stable sub-micron lipid vesicles.
Nonetheless, the current liposome preparation technologies (sonication10, freeze-and-thaw10, sedimentation) do not allow preparation of liposomes with highly curved surface (i.e. diameter &lt;100 nm) with high consistency and efficiency10,5, which limits the biophysical studies of an emerging field of membrane curvature sensing. Herein, we present a robust preparation method for a variety of biologically relevant liposomes.
Manual extrusion using gas-tight syringes and polycarbonate membranes10,5 is a common practice but heterogeneity is often observed when using pore sizes &lt;100 nm due to due to variability of manual pressure applied. We employed a constant pressure-controlled extrusion apparatus to prepare synthetic liposomes whose diameters range between 30 and 400 nm. Dynamic light scattering (DLS)10, electron microscopy11 and nanoparticle tracking analysis (NTA)12 were used to quantify the liposome sizes as described in our protocol, with commercial polystyrene (PS) beads used as a calibration standard. A near linear correlation was observed between the employed pore sizes and the experimentally determined liposomes, indicating high fidelity of our pressure-controlled liposome preparation method. Further, we have shown that this lipid vesicle preparation method is generally applicable, independent of various liposome sizes. Lastly, we have also demonstrated in a time course study that these prepared liposomes were stable for up to 16 hours. A representative nano-sized liposome preparation protocol is demonstrated below.

This protocol describes an extrusion method for preparing lipid vesicles of sub-micron sizes with a high degree of homogeneity. This method uses a pressure-controlled system with controlled nitrogen flow rates for liposome preparation. The lipid preparation1,2, liposome extrusion, and size characterization will be presented herein.

Liposomes are artificially prepared vesicles consisting of natural and synthetic phospholipids that are widely used as a cell membrane mimicking platform ...

Bioengineering

Solid Lipid Nanoparticles (SLNs) for Intracellular Targeting Applications

Nanoparticle-based delivery vehicles have shown great promise for intracellular targeting applications, providing a mechanism to specifically alter cellular signaling and gene expression. In a previous investigation, the synthesis of ultra-small solid lipid nanoparticles (SLNs) for topical drug delivery and biomarker detection applications was demonstrated. SLNs are a well-studied example of a nanoparticle delivery system that has emerged as a promising drug delivery vehicle. In this study, SLNs were loaded with a fluorescent dye and used as a model to investigate particle-cell interactions. The phase inversion temperature (PIT) method was used for the synthesis of ultra-small populations of biocompatible nanoparticles. A 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenylphenyltetrazolium bromide (MTT) assay was utilized in order to establish appropriate dosing levels prior to the nanoparticle-cell interaction studies. Furthermore, primary human dermal fibroblasts and mouse dendritic cells were exposed to dye-loaded SLN over time and the interactions with respect to toxicity and particle uptake were characterized using fluorescence microscopy and flow cytometry. This study demonstrated that ultra-small SLNs, as a nanoparticle delivery system, are suitable for intracellular targeting of different cell types.

Solid Lipid Nanoparticles SLNs for Intracellular Targeting Applications

In this study, a method for synthesizing ultra-small populations of biocompatible nanoparticles was described, as well as several in vitro methods by which to assess their cellular interactions.

Nanoparticle-based delivery vehicles have shown great promise for intracellular targeting applications, providing a mechanism to specifically alter ...

Targeted Plasma Membrane Delivery of a Hydrophobic Cargo Encapsulated in a Liquid Crystal Nanoparticle Carrier

The controlled delivery of drug/imaging agents to cells is critical for the development of therapeutics and for the study of cellular signaling processes. Recently, nanoparticles (NPs) have shown significant promise in the development of such delivery systems. Here, a liquid crystal NP (LCNP)-based delivery system has been employed for the controlled delivery of a water-insoluble dye, 3,3&#8242;-dioctadecyloxacarbocyanine perchlorate (DiO), from within the NP core to the hydrophobic region of a plasma membrane bilayer. During the synthesis of the NPs, the dye was efficiently incorporated into the hydrophobic LCNP core, as confirmed by multiple spectroscopic analyses. Conjugation of a PEGylated cholesterol derivative to the NP surface (DiO-LCNP-PEG-Chol) enabled the binding of the dye-loaded NPs to the plasma membrane in HEK 293T/17 cells. Time-resolved laser scanning confocal microscopy and F&#246;rster resonance energy transfer (FRET) imaging confirmed the passive efflux of DiO from the LCNP core and its insertion into the plasma membrane bilayer. Finally, the delivery of DiO as a LCNP-PEG-Chol attenuated the cytotoxicity of DiO; the NP form of DiO exhibited ~30-40% less toxicity compared to DiOfree delivered from bulk solution. This approach demonstrates the utility of the LCNP platform as an efficient modality for the membrane-specific delivery and modulation of hydrophobic molecular cargos.

A liquid crystal nanoparticle (LCNP) nanocarrier is exploited as a vehicle for the controlled delivery of a hydrophobic cargo to the plasma membrane of living cells.

The controlled delivery of drug/imaging agents to cells is critical for the development of therapeutics and for the study of cellular signaling processes. ...

Formulation and Characterization of Bioactive Agent Containing Nanodisks

The term nanodisk refers to a discrete type of nanoparticle comprised of a bilayer forming lipid, a scaffold protein, and an integrated bioactive agent. Nanodisks are organized as a disk-shaped lipid bilayer whose perimeter is circumscribed by the scaffold protein, usually a member of the exchangeable apolipoprotein family. Numerous hydrophobic bioactive agents have been efficiently solubilized in nanodisks by their integration into the hydrophobic milieu of the particle&#39;s lipid bilayer, yielding a largely homogenous population of particles in the range of 10-20 nm in diameter. The formulation of nanodisks requires a precise ratio of individual components, an appropriate sequential addition of each component, followed by bath sonication of the formulation mixture. The amphipathic scaffold protein spontaneously contacts and reorganizes the dispersed bilayer forming lipid/bioactive agent mixture to form a discrete, homogeneous population of nanodisk&#160;particles. During this process, the reaction mixture transitions from an opaque, turbid appearance to a clarified sample that, when fully optimized, yields no precipitate upon centrifugation. Characterization studies involve the determination of bioactive agent solubilization efficiency, electron microscopy, gel filtration chromatography, ultraviolet visible (UV/Vis) absorbance spectroscopy, and/or fluorescence spectroscopy. This is normally followed by an investigation of biological activity using cultured cells or mice. In the case of nanodisks harboring an antibiotic (i.e., the macrolide polyene antibiotic amphotericin B), their ability to inhibit the growth of yeast or fungi as a function of concentration or time can be measured. The relative ease of formulation, versatility with respect to component parts, nanoscale particle size, inherent stability, and aqueous solubility permits myriad in vitro and in vivo applications of nanodisk technology. In the present article, we describe a general methodology to formulate and characterize nanodisks containing amphotericin&#160;B as the hydrophobic bioactive agent.

Here, we describe the production and characterization of bioactive agents containing nanodisks. Amphotericin B nanodisks are taken as an example to describe the protocol in a stepwise manner.

The term nanodisk refers to a discrete type of nanoparticle comprised of a bilayer forming lipid, a scaffold protein, and an integrated bioactive agent. ...

Biochemistry

Flash NanoPrecipitation for the Encapsulation of Hydrophobic and Hydrophilic Compounds in Polymeric Nanoparticles

The formulation of a therapeutic compound into nanoparticles (NPs) can impart unique properties. For poorly water-soluble drugs, NP formulations can improve bioavailability and modify drug distribution within the body. For hydrophilic drugs like peptides or proteins, encapsulation within NPs can also provide protection from natural clearance mechanisms. There are few techniques for the production of polymeric NPs that are scalable. Flash NanoPrecipitation (FNP) is a process that uses engineered mixing geometries to produce NPs with narrow size distributions and tunable sizes between 30 and 400 nm. This protocol provides instructions on the laboratory-scale production of core-shell polymeric nanoparticles of a target size using FNP. The protocol can be implemented to encapsulate either hydrophilic or hydrophobic compounds with only minor modifications. The technique can be readily employed in the laboratory at milligram scale to screen formulations. Lead hits can directly be scaled up to gram- and kilogram-scale. As a continuous process, scale-up involves longer mixing process run time rather than translation to new process vessels. NPs produced by FNP are highly loaded with therapeutic, feature a dense stabilizing polymer brush, and have a size reproducibility of &#177; 6%.

Flash NanoPrecipitation (FNP) is a scalable approach to produce polymeric core-shell nanoparticles. Lab-scale formulations for the encapsulation of hydrophobic or hydrophilic therapeutics are described.

The formulation of a therapeutic compound into nanoparticles (NPs) can impart unique properties. For poorly water-soluble drugs, NP formulations can ...

Uptake of New Lipid-coated Nanoparticles Containing Falcarindiol by Human Mesenchymal Stem Cells

Nanoparticles are the focus of an increased interest in drug delivery systems for cancer therapy. Lipid-coated nanoparticles are inspired in structure and size by low-density lipoproteins (LDLs) because cancer cells have an increased need for cholesterol to proliferate, and this has been exploited as a mechanism for delivering anticancer drugs to cancer cells. Moreover, depending on drug chemistry, encapsulating the drug can be advantageous to avoid degradation of the drug during circulation in vivo. Therefore, in this&#160;study, this design is used to fabricate lipid-coated nanoparticles of the anticancer drug falcarindiol, providing a potential new delivery system of falcarindiol in order to stabilize its chemical structure against degradation and improve its uptake by tumors. Falcarindiol nanoparticles, with a phospholipid and cholesterol monolayer encapsulating the purified drug core of the particle, were designed. The lipid monolayer coating consists of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), cholesterol (Chol), and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE PEG 2000) along with the fluorescent label DiI (molar ratios of 43:50:5:2). The nanoparticles are fabricated using the rapid injection method, which is a fast and simple technique to precipitate nanoparticles by good-solvent for anti-solvent exchange. It consists of a rapid injection of an ethanol solution containing the nanoparticle components into an aqueous phase. The size of the fluorescent nanoparticles is measured using dynamic light scattering (DLS) at 74.1 &#177; 6.7 nm. The uptake of the nanoparticles is tested in human mesenchymal stem cells (hMSCs) and imaged using fluorescence and confocal microscopy. The uptake of the nanoparticles is observed in hMSCs, suggesting the potential for such a stable drug delivery system for falcarindiol.

This article describes the encapsulation of falcarindiol in lipid-coated 74 nm nanoparticles. The cellular uptake of the nanoparticles&#160;by human stem cells into lipid droplets is monitored by fluorescent and confocal imaging. Nanoparticles are fabricated by the rapid injection method of solvent shifting, and their size is measured with the dynamic light scattering technique.

Nanoparticles are the focus of an increased interest in drug delivery systems for cancer therapy. Lipid-coated nanoparticles are inspired in structure and ...

Preparation and Characterization of Nanoliposomes for the Entrapment of Bioactive Hydrophilic Globular Proteins

Liposome nanocapsules have been applied for many purposes in the pharmaceutical, cosmetic, and food industries. Attributes of liposomes include their biocompatibility, biodegradability, non-immunogenicity, non-toxicity, and ability to entrap both hydrophilic and hydrophobic compounds. The classical hydration of thin lipid films in an organic solvent is applied herein as a technique to encapsulate tarin, a plant lectin, in nanoliposomes. Nanoliposome size, stability, entrapment efficiency, and morphological characterization are described in detail. The nanoliposomes are prepared using 1,2-dioleoyl-sn-glycerol-3-phosphoethanolamine (DOPE), 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000] (ammonium salt; DSPE-MPEG 2000), and cholesterylhemisuccinate (CHEMS) as the main constituents. Lipids are first dissolved in chloroform to obtain a thin lipid film that is subsequently rehydrated in ammonium sulfate solution containing the protein to be entrapped and incubated overnight. Then, sonication and extrusion techniques are applied to generate nanosized unilamellar vesicles. The size and polydispersity index of the nanovesicles are determined by dynamic light scattering, while nanovesicle morphology is assessed by scanning electron microscopy. Entrapment efficiency is determined by the ratio of the amount of unencapsulated protein to original amount of initially loaded protein. Homogeneous liposomes are obtained with an average size of 155 nm and polydispersity index value of 0.168. A high entrapment efficiency of 83% is achieved.

This study describes classical hydration using the thin lipid film method for nanoliposome preparation followed by nanoparticle characterization. A 47 kDa-hydrophilic and globular protein, tarin, is successfully encapsulated as a strategy to improve stability, avoid fast clearance, and promote controlled release. The method can be adapted to hydrophobic molecules encapsulation.

Liposome nanocapsules have been applied for many purposes in the pharmaceutical, cosmetic, and food industries. Attributes of liposomes include their ...

Microfluidic Production of Lysolipid-Containing Temperature-Sensitive Liposomes

The presented protocol enables a high-throughput continuous preparation of low temperature-sensitive liposomes (LTSLs), which are capable of loading chemotherapeutic drugs, such as doxorubicin (DOX). To achieve this, an ethanolic lipid mixture and ammonium sulfate solution are injected into a staggered herringbone micromixer (SHM) microfluidic device. The solutions are rapidly mixed by the SHM, providing a homogeneous solvent environment for liposomes self-assembly. Collected liposomes are first annealed, then dialyzed to remove residual ethanol. An ammonium sulfate pH-gradient is established through buffer exchange of the external solution by using size exclusion chromatography. DOX is then remotely loaded into the liposomes with high encapsulation efficiency (&#62; 80%). The liposomes obtained are homogenous in size with Z-average diameter of 100 nm. They are capable of temperature-triggered burst release of encapsulated DOX in the presence of mild hyperthermia (42 &#176;C). Indocyanine green (ICG) can also be co-loaded into the liposomes for near-infrared laser-triggered DOX release. The microfluidic approach ensures high-throughput, reproducible and scalable preparation of LTSLs.

The protocol presents the optimized parameters for preparing thermosensitive liposomes using the staggered herringbone micromixer microfluidics device. This also allows co-encapsulation of doxorubicin and indocyanine green into the liposomes and the photothermal-triggered release of doxorubicin for controlled/triggered drug release.

The presented protocol enables a high-throughput continuous preparation of low temperature-sensitive liposomes (LTSLs), which are capable of loading ...