The authors acknowledge the Saudi Arabia-funded scholarship (I821) for making the research possible. The authors are grateful to Dr Xianwei Liu for expert support in TEM analysis at Cranfield University.

1. Preparation of Oil-in-water Emulsion
<ol>
	<li>Weigh glyceryl palmitostearate (120 mg), isopropyl myristate (60 mg), d-&#945;-tocopheryl polyethylene glycol succinate (30 mg) and soybean lecithin (30 mg), and add them to 12.5 ml of organic solvents (6.25 ml acetone and 6.25 ml ethanol). Quickly dissolve the mixture at the temperature 70&#160;&#176;C (5 &#176;C above the melting point of the solid lipid) in water bath.</li>
	<li>Add either 125, 250 or 375 mg of Poloxamer188 in 12.5 ml of ddH2O to achieve 1-3% (respectively) of Poloxamer 188 solution, which is subject to heating at the same temperature as above.</li>
	<li>Add the aqueous phase solution from step 1.2 to the oil phase solution from step 1.1 dropwise to form emulsions under magnetic stirring at 400 rpm . Stir the emulsion at 400 rpm for another 4 hr to allow evaporation of the organic solvents.</li>
</ol>
2. Solidification and Homogenization
<ol>
	<li>Leave the emulsion in a cold room (4 &#176;C) for 2 hr to solidify/crystallize.</li>
	<li>To obtain NLC, subject the emulsion to high sheer dispersion (HSD) with a homogenizer at 10,000-15,000 rpm for 10-40 min.</li>
</ol>
3. Optimization of the NLC Preparation
<ol>
	<li>Take samples from step 2.2 with a surfactant concentration of 1, 2 and 3% undergoing HSD at speeds of 10,000, 15,000 and 20,000 rpm, respectively, and time intervals of 10, 20, 30 and 40 min, respectively,</li>
	<li>Examine the samples for particle size (PS), poly dispersion index (PDI), morphology and ultrastructure 20. 
	Note: The parameters that produce particles with the smallest size (155 nm) and PDI (0.2) value are determined as optimal.</li>
</ol>
4. Preparation of Dac-loaded NLC (NLC-Dac)
<ol>
	<li>Prepare oil phase solution as described in step 1.1 with the addition of Dac (70 mg) before dissolving the mixture at 70 &#176;C in water bath.</li>
	<li>Prepare an aqueous phase solution as described in step 1.2 with 1% surfactant, and add this solution to that prepared in step 4.1 dropwise to form an emulsion under magnetic stirring at 400 rpm. Stir the emulsion for further 4 hr to evaporate the organic solvents.</li>
	<li>Leave the emulsion in a cold room (4 &#176;C) for 2 hr to solidify/crystallize as described in step 2, and finally, subject the emulsion to high sheer dispersion (HSD) using the optimal parameters determined in step 3.</li>
</ol>

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The authors have nothing to disclose.

Lipid-based nanostructured particles have been utilized to provide a highly lipophilic carrier for delivery of hydrophobic drugs. A NLC is the second generation of solid lipid nanostructured carrier, which are solid at room and body temperature. The incorporation of a solid lipid into a liquid lipid in a NLC results in a less perfect crystallization, thus increasing the drug loading efficiency and also reducing the expulsion of encapsulated drugs during storage.
For NLC synthesis, the most commonly used method involves oil-in-water emulsion, homogenization and solidification/crystallization 21,22. The homogenization allows NLCs to disperse thoroughly in an aqueous phase, whilst the solidification at low temperature allows the inner oil phase to crystallize. Different homogenization methods have been reported including magnetic stirring, ultrasonication, and HSD that are used before and/or during solidification 23,24.
In this study, the commonly used method was initially followed for NLC preparation. As the result was unsatisfactory, the method was modified such that HSD was applied after solidification. This modification proved highly effective in particle generation, PS and PDI control, while also making the NLC synthesis simpler, compared with previous reports on NLC preparation using the same lipids 23,25. It was worth noting that the length of the evaporation (protocol 1.3) and solidification (protocol 2.1) is very critical as too long or too short a time would have negative effects on the generation of NLC.
This study suggests that NLC particles and their aggregation were formed during solidification. The HSD could disrupt the aggregation, which was possibly due to hydrophobic interaction between NLCs, and also stabilize the particles by thoroughly remixing them with surfactant. The synthesis procedure was optimized such that the NLC and NLC-Dac were produced with a size 155 &#177; 10 nm and 190 &#177; 10 nm, respectively, and a PDI of 0.2 &#177; 0.01. The high level of uniformity with particle sizes and the small PDI values indicates that a sufficient dispersion energy was achieved and is well distributed within the solution for disruption of particle aggregates. It has been suggested that particles of 100-200 nm are not prone to uptake by non-targeted cells, including mononuclear phagocytic system, thus having a long blood circulation time in vivo 26,27, whilst a PDI of more than 0.5 is an indication of particle aggregation 28; the lower the PDI value, the higher the size homogeneity between the particles 29. Further increase of the HSD speed and time above the optimal point could result in further PS reduction, and consequently an increase in interactions between small particles as well as re-aggregation. The difference in size and structure between NLC and NLC-Dac suggests that the Dac loading and encapsulation was successful. The drug binding to the outer layer of the NLC and encapsulation inside lipid matrices provide the potential for prolonged drug release, that could involve drug release firstly from the outer layer, followed by the release from the liquid lipid matrix and then from the solid lipid crystals of the NLC 30.
Currently four nanoformulations have been attempted for delivery of Dac as a single agent. The latest formulation reported was designed for duel encapsulation of Dac and vitamin A 32. However these formulations suffered from a low encapsulation efficiency and/or relatively complex synthesis procedures. This is the first report for encapsulation of Dac with a NLC, proving advantageous over other encapsulations reported previously. NLC-Dac is easy to make and presents higher drug encapsulation and drug loading efficiency 20. The NLC-Dac showed nearly 50% of drug released within the first 2 hr whilst the remaining released slowly for up to 30 hr 20. The early release could be due to the binding of the drug with surfactant layer on the surface of the NLC, indicating that this formulation may not be ideal to replace the formulation currently in clinical use. However the drug in NLC-Dac appeared more stable compared with the nanoemulsion reported previously 10. In addition, lipid based vehicles have been proposed for treating cutaneous melanoma and epidermoid carcinoma through topical drug delivery 32,10, indicating that the NLC-Dac developed in this study could also be potentially beneficial for topical application where early drug release would not potentially lead to severe systemic toxicity.
Due to the collective limitations with the available drug delivery carriers developed so far, further research is needed to develop more advanced nanomaterials for Dac delivery for targeted cancer treatment.

Dacarbazine (Dac) is an alkylating agent that exerts anti-tumor activity through nucleic acids methylation or direct DNA damage, leading to cell cycle arrest and cell death 1.
As a first line chemotherapeutic agent, Dac has been used alone or in combination with other chemotherapy drugs for treating various cancers 2-6. It is the most active agent so far used in treating cutaneous and metastatic melanoma, which is the most aggressive form of skin cancer 3,7,8. The response rate, however, is only 20% at best, and the therapeutic effects are often accompanied with severe systemic side effects.
In its natural form, Dac is hydrophilic and is unstable due to its photosensitivity 9. The only available formula for clinical use currently is a sterile powder to be used in suspension for intravenous infusion 7,8. The low response rate and high systemic toxicity rate of the drug is largely attributable to its poor water solubility, therefore low availability at target site, and high distribution at non-target sites, which limits the maximum dose of the drug 10. The rapid degradation and metabolism after intravenous admission together with the development of drug resistance limit the clinical application and therapeutic effect of the drug 11. Therefore, there is an urgent need to develop alternative Dac formulations for treating malignant melanoma.
Colloidal systems containing liposomes, micelles or nanostructured particles have been intensively investigated for their use in drug delivery as reviewed by Marilene et al. 12 Nanostructured particles as potential drug carriers have been attracting increasing attention in the last decade due to their ability to increase drug loading efficiency, control drug release, improve drug pharmacokinetics and biodistribution, and therefore reduce drug systemic toxicity 13. Only a few nanoformulations, however, have been investigated so far for Dac delivery, showing protection of the drug from photo degeneration, increased drug solubility, and improved therapeutic effect 10,14,15. However these formulations suffered from low encapsulating efficiency while some also using synthetic polymer nanoparticles that are not cost effective.
Nanostructured lipid carriers (NLC), made of a mixture of solid and liquid lipids, have been developed for drug delivery 16,17. The drugs to be encapsulated are often soluble in both the liquid lipids and solid lipids phases 18, resulting in a high loading and controlled release 19. This study aims to develop a new Dac formulation based on NLC-encapsulation using glyceryl palmitostearate and isopropyl myristate as lipids. The preparation involved oil-in-water emulsion, evaporation, solidification, and homogenization. The preparations have been characterized for NLC size, shape, ultrastructure, and dispersity, drug encapsulation efficiency and drug loading 20.

<table><tbody><tr><td>Dacarbazine (DAC)</td><td>Sigma Aldrich (Gillingham Dorset, UK)</td><td>D2390-100MG</td><td>drug used for uploading</td></tr><tr><td>glyceryl palmitostearate&amp;nbsp;</td><td>Gattefoss&amp;eacute; (Saint_Priest_c&amp;eacute;dex, France)</td><td>85251-77-0</td><td>solid lipid&amp;nbsp;</td></tr><tr><td>d-&amp;alpha;- Tocopherol polyethylene glycol succinate (TPGS)</td><td>Sigma Aldrich (Gillingham Dorset, UK)</td><td>57668</td><td>lipid phase surfactant</td></tr><tr><td>Poloxamer 188</td><td>Sigma Aldrich (Gillingham Dorset, UK)</td><td>15759-1KG</td><td>liqiud phase surfactant</td></tr><tr><td>Acetone&amp;nbsp;</td><td>Sigma Aldrich (Gillingham Dorset, UK)</td><td>650501-1L</td><td>organic solvent</td></tr><tr><td>Ethanol&amp;nbsp;</td><td>Sigma Aldrich (Gillingham Dorset, UK)</td><td>459836-1L</td><td>organic solvent</td></tr><tr><td>Soybean lecithin (SL)</td><td>Cuisine Innovation (Dijon, France)</td><td>SLL1402</td><td>lipid phase surfactant</td></tr><tr><td>Double-distilled water was collected in our laboratory from</td><td>Millipore-Q Gradient A10 ultra-pure water system (Millipore, France)</td><td>SAS - 67120&amp;nbsp;</td><td>aqueous phase&amp;nbsp;</td></tr><tr><td>T 25 digital ULTRA-TURRAX</td><td>IKA</td><td>3725000</td><td>as high shear disperser</td></tr><tr><td>Hotplate Magnetic Stirrer</td><td>Scientific Support, Inc</td><td>1454&amp;nbsp;</td><td>emulsion homogenization</td></tr></tbody></table>

encapsulation of cancer therapeutic agent dacarbazine using nanostructured lipid carrier

The only formula of dacarbazine (Dac) in clinical use is intravenous infusion, presenting a poor therapeutic profile due to the low dispersity of the drug in aqueous solution. To overcome this, a nanostructured lipid carrier (NLC) consisting of glyceryl palmitostearate and isopropyl myristate was developed to encapsulate Dac. NLCs with controlled size were achieved using high shear dispersion (HSD) following solidification of oil-in-water emulsion. The synthesis parameters, including surfactant concentration, the speed and time of HSD were optimized to achieve the smallest NLC with size, polydispersion index and zeta potential of 155 &#177; 10 nm, 0.2 &#177; 0.01, and -43.4 &#177; 2 mV, respectively. The optimal parameters were also employed for Dac-loaded NLC preparation. The resultant NLC loaded with Dac possessed size, polydispersion index and zeta potential of 190 &#177; 10 nm, 0.2 &#177; 0.01, and -43.5 &#177; 1.2 mV, respectively. The drug encapsulation efficiency and drug loading reached 98% and 14%, respectively. This is the first report on encapsulation of Dac using NLC, implying that NLC could be a new potential candidate as drug carrier to improve the therapeutic profile of Dac.

The preparations of the NLC and NLC-Dac using glyceryl palmitostearate and isopropyl myristate with different parameters were characterized for PS, PDI, morphology and ultrastructure 20. The PS and PDI of the NLCs were surfactant concentration, HSD speed and duration dependent. As judged by PS and PDI of the NLCs, the best results were achieved with 1% of surfactant and a sheer dispersion speed of 15,000 rpm for 30 min (Figure 1A, B and C), which therefore wwew selected as the optimal parameters for NLC preparation in this study.
<img alt="Figure 1" src="/files/ftp_upload/53760/53760fig1.jpg" /> 
Figure 1.&#160;Optimization of parameters used in NLC preparation. The optimal surfactant concentration and the speed and time of HSD were determined according to their effect on PS and PDI. (A) Effect of surfactant concentration on PS; (B) Effect of HSD speed and time on PS; (C) Effect of HSD speed and time on PDI. This Figure has been modified from 20. The data are presented as mean value of 3 replicates &#177; standard deviation (mean &#177; SD).
The optimal parameters were used for NLC-Dac preparation. The smallest size achieved was 150 &#177; 10 nm for NLC (Figure 2A) and 190 &#177; 10 nm for NLC-Dac (Figure 2B), both with PDI of 0.2 &#177; 0.001, indicating a good uniformity.
<img alt="Figure 2" src="/files/ftp_upload/53760/53760fig2.jpg" /> 
Figure 2.&#160;DLS measurement of NLC. (A) The optimal size distribution of plain NLC; (B) the optimal size distribution of NLC-Dac.
Both NLC and NLC-Dac showed a spherical shape as observed under TEM (Figure 3).
<img alt="Figure 3" src="/files/ftp_upload/53760/53760fig3.jpg" /> 
Figure 3. TEM imaging of NLC and NLC-Dac. Both NLC and NLC-Dac showed a spherical shape. (A) Basic NLC structure comprises a surfactant layer (solid black arrow), liquid lipid matrix (white solid arrow), and solid lipid crystals (dotted white arrows); (B) NLC-Dac also exhibited the basic structure as seen in NLC but the surfactant layer, liquid lipid matrix and solid lipid crystals appeared expanded; an extra substructure could be seen inside the solid lipid crystals (indicated by dotted black arrows), indicative of drug loading. Bar scale: 50 nm, Magnification: 55,000X. This Figure has been modified from 20.
The uploading and encapsulation of Dac in NLC is indicated by the size and structure changes as seen in Figures 2 and 3 where NLC-Dac shows a larger size and altered internal structures as compared with NLC. The basic structure of NLC comprises a surfactant layer, a liquid lipid matrix and solid lipid crystals (Figure 3A). NLC-Dac also exhibited the basic structure as a NLC but with expanded surfactant layer, liquid lipid matrix and solid lipid crystals, together with an extra substructure inside the solid lipid crystals (Figure 3B), indicative of drug loading and encapsulation. The solid lipid crystals seen in NLC appeared denser than that in NLC-Dac, indicating that the solid lipid is less crystallized in NLC-Dac.
The drug encapsulation efficiency (EF) and drug loading (DL) percentage were derived from the following equations:
EE% = W1 - W2/W1 x 100 = 98.5%
DL% = W1 - W2/W3 x 100 = 14%
where W1 amount of Dac added in the NLC, W2 amount of un-entrapped Dac, W3 amount of the lipids added 20.

Watch this Scientific Journal Video about Encapsulation of Cancer Therapeutic Agent Dacarbazine Using Nanostructured Lipid Carrier at JoVE.com

Encapsulation of Cancer Therapeutic Agent Dacarbazine Using Nanostructured Lipid Carrier

The most commonly used method for nanostructured lipid carrier (NLC) synthesis involves oil-in-water emulsion, homogenization and solidification. This was modified here by applying high shear dispersion after solidification to achieve a NLC with desirable size, improved drug encapsulation and drug loading efficiency as a potential carrier for dacarbazine delivery.

The only formula of dacarbazine (Dac) in clinical use is intravenous infusion, presenting a poor therapeutic profile due to the low dispersity of the drug ...

encapsulation-cancer-therapeutic-agent-dacarbazine-using

Nanyang Technological University

Research

JoVE Journal

Chemistry

11.1K Views.  Cranfield University.  De meest gebruikte methode voor het nanogestructureerde lipidedrager (NAR) synthese zijn olie-in-water emulsie, homogenisering en stollen. Dit werd hier aangepast door het toepassen van een hoge afschuiving dispersie na het stollen een NLC met gewenste grootte, verbeterde drug inkapseling en drugs laden efficiency als een potentiële drager voor dacarbazine levering te bereiken. 

Video: Encapsulation of Cancer Therapeutic Agent Dacarbazine Using Nanostructured Lipid Carrier

Anticancer Efficacy of Photodynamic Therapy with Lung Cancer-Targeted Nanoparticles

Photodynamic therapy (PDT) is a non-invasive and non-surgical method representing an attractive alternative choice for lung cancer treatment. Photosensitizers selectively accumulate in tumor tissue and lead to tumor cell death in the presence of oxygen and the proper wavelength of light.
To increase the therapeutic effect of PDT, we developed both photosensitizer- and anticancer agent-loaded lung cancer-targeted nanoparticles. Both enhanced permeability and retention (EPR) effect-based passive targeting and hyaluronic-acid-CD44 interaction-based active targeting were applied. CD44 is a well-known hyaluronic acid receptor that is often introduced as a biomarker of non-small cell lung cancer. 
In addition, a combination of PDT and chemotherapy is adopted in the present study. This combination concept may increase anticancer therapeutic effects and reduce adverse reactions. 
We chose hypocrellin B (HB) as a novel photosensitizer in this study. It has been reported that HB causes higher anticancer efficacy of PDT compared to hematoporphyrin derivatives1. Paclitaxel was selected as the anticancer drug since it has proven to be a potential treatment for lung cancer2. 
The antitumor efficacies of photosensitizer (HB) solution, photosensitizer encapsulated hyaluronic acid-ceramide nanoparticles (HB-NPs), and both photosensitizer- and anticancer agent (paclitaxel)-encapsulated hyaluronic acid-ceramide nanoparticles (HB-P-NPs) after PDT were compared both in vitro and in vivo. The in vitro phototoxicity in A549 (human lung adenocarcinoma) cells and the in vivo antitumor efficacy in A549 tumor-bearing mice were evaluated.
The HB-P-NP treatment group showed the most effective anticancer effect after PDT. In conclusion, the HB-P-NPs prepared in the present study represent a potential and novel photosensitizer delivery system in treating lung cancer with PDT.

Photodynamic therapy (PDT) is an alternative choice for lung cancer treatment. To increase the therapeutic effect of PDT, lung cancer-targeted nanoparticles combined with chemotherapy were developed. Both in vitro and in vivo anticancer efficacies of PDT with prepared nanoparticles were evaluated.

Photodynamic therapy (PDT) is a non-invasive and non-surgical method representing an attractive alternative choice for lung cancer treatment. ...

Cancer Research

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 ...

Custom-designed Laser-based Heating Apparatus for Triggered Release of Cisplatin from Thermosensitive Liposomes with Magnetic Resonance Image Guidance

Liposomes have been employed as drug delivery systems to target solid tumors through exploitation of the enhanced permeability and retention (EPR) effect resulting in significant reductions in systemic toxicity. Nonetheless, insufficient release of encapsulated drug from liposomes has limited their clinical efficacy. Temperature-sensitive liposomes have been engineered to provide site-specific release of drug in order to overcome the problem of limited tumor drug bioavailability. Our lab has designed and developed a heat-activated thermosensitive liposome formulation of cisplatin (CDDP), known as HTLC, to provide triggered release of CDDP at solid tumors. Heat-activated delivery in vivo was achieved in murine models using a custom-built laser-based heating apparatus that provides a conformal heating pattern at the tumor site as confirmed by MR thermometry (MRT). A fiber optic temperature monitoring device was used to measure the temperature in real-time during the entire heating period with online adjustment of heat delivery by alternating the laser power. Drug delivery was optimized under magnetic resonance (MR) image guidance by co-encapsulation of an MR contrast agent (i.e.,&#160;gadoteridol) along with CDDP into the thermosensitive liposomes as a means to validate the heating protocol and to assess tumor accumulation. The heating protocol consisted of a preheating period of 5 min prior to administration of HTLC and 20 min heating post-injection. This heating protocol resulted in effective release of the encapsulated agents with the highest MR signal change observed in the heated tumor in comparison to the unheated tumor and muscle. This study demonstrated the successful application of the laser-based heating apparatus for preclinical thermosensitive liposome development and the importance of MR-guided validation of the heating protocol for optimization of drug delivery.

AN MRI-compatible&#160;custom-designed laser-based heating apparatus has been developed to provide local heating of subcutaneous tumors in order to activate release of agents from thermosensitive liposomes specifically at the tumor region.

Liposomes have been employed as drug delivery systems to target solid tumors through exploitation of the enhanced permeability and retention (EPR) effect ...

Bioengineering

Preparation and Characterization of Lipophilic Doxorubicin Pro-drug Micelles

Micelles have been successfully used for the delivery of anticancer drugs. Amphiphilic polymers form core-shell structured micelles in an aqueous environment through self-assembly. The hydrophobic core of micelles functions as a drug reservoir and encapsulates hydrophobic drugs. The hydrophilic shell prevents the aggregation of micelles and also prolongs their systemic circulation in vivo. In this protocol, we describe a method to synthesize a doxorubicin lipophilic pro-drug, doxorubicin-palmitic acid (DOX-PA), which will enhance drug loading into micelles. A pH-sensitive hydrazone linker was used to conjugate doxorubicin with the lipid, which facilitates the release of free doxorubicin inside cancer cells. Synthesized DOX-PA was purified with a silica gel column using dichloromethane/methanol as the eluent. Purified DOX-PA was analyzed with thin layer chromatography (TLC) and 1H-Nuclear Magnetic Resonance Spectroscopy (1H-NMR). A film dispersion method was used to prepare DOX-PA loaded DSPE-PEG micelles. In addition, several methods for characterizing micelle formulations are described, including determination of DOX-PA concentration and encapsulation efficiency, measurement of particle size and distribution, and assessment of in vitro anticancer activities. This protocol provides useful information regarding the preparation and characterization of drug-loaded micelles and thus will facilitate the research and development of novel micelle-based cancer nanomedicines.

A protocol for the preparation and characterization of lipophilic doxorubicin pro-drug loaded 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000] (DSPE-PEG) micelles is described.

Micelles have been successfully used for the delivery of anticancer drugs. Amphiphilic polymers form core-shell structured micelles in an aqueous ...

Phase Change Dimethyldioctadecylammonium-Shelled Microdroplets as a Promising Drug Delivery System: Results on 3D Spheroids of Mammalian Tumor Cells

Significant improvement of phase-change perfluorocarbon microdroplets (MDs) in the vast theranostic scenario passes through the optimization of the MDs composition with respect to synthesis efficiency, stability, and drug delivery capability. To this aim, decafluoropentane (DFP) MDs stabilized by a shell of dimethyldioctadecylammonium bromide (DDAB) cationic surfactant were designed. A high concentration of DDAB-MDs was readily obtained within a few seconds by pulsed high-power insonation, resulting in low polydisperse 1 &#181;m size droplets. Highly positive &#950;-potential, together with a long, saturated hydrocarbon chains of the DDAB shell, are key factors to stabilize the droplet and the drug cargo therein. The high affinity of the DDAB shell with cell plasma membrane allows for localized chemotherapeutics delivery by increasing the drug concentration at the tumor cell interface and boosting the uptake. This would turn DDAB-MDs into a relevant drug delivery tool exhibiting high antitumor activity at very low drug doses.
In this work, the efficacy of such an approach is shown to dramatically improve the effect of doxorubicin against 3D spheroids of mammalian tumor cells, MDA-MB-231. The use of&#160;three-dimensional (3D) cell cultures developed in the form of multicellular tumor spheroids (i.e., densely packed cells in a spherical shape) has numerous advantages compared to 2D cell cultures: in addition to have the potential to bridge the gap between conventional in vitro studies and animal testing, it will improve the ability to perform more predictive in vitro screening assays for preclinical drug development or evaluate the potential of off-label drugs and new co-targeting strategies.

Decafluoropentane microdroplets developed with a shell of dimethyldioctadecylammonium bromide exhibited an exceptional colloidal stability and an actractive biointerface. DDAB-MDs proved to be efficient drug reservoirs characterized by a high affinity to plasma membranes together with enhanced uptake and antitumor activity of Doxorubicin against human triple-negative breast cancer (MDA-MB-231) 3D model.

Significant improvement of phase-change perfluorocarbon microdroplets (MDs) in the vast theranostic scenario passes through the optimization of the MDs ...

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

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 ...

Using In Vitro Live-cell Imaging to Explore Chemotherapeutics Delivered by Lipid-based Nanoparticles

Conventional imaging techniques can provide detailed information about cellular processes. However, this information is based on static images in an otherwise dynamic system, and successive phases are easily overlooked or misinterpreted. Live-cell imaging and time-lapse microscopy, in which living cells can be followed for hours or even days in a more or less continuous fashion, are therefore very informative. The protocol described here allows for the investigation of the fate of chemotherapeutic nanoparticles after the delivery of doxorubicin (dox) in living cells. Dox is an intercalating agent that must be released from its nanocarrier to become biologically active. In spite of its clinical registration for more than two decades, its uptake, breakdown, and drug release are still not fully understood. This article explores the hypothesis that lipid-based nanoparticles are taken up by the tumor cells and are slowly degraded. Released dox is then translocated to the nucleus. To prevent fixation artifacts, live-cell imaging and time-lapse microscopy, described in this experimental procedure, can be applied.

Using In Vitro Live-cell Imaging to Explore Chemotherapeutics Delivered by Lipid-based Nanoparticles

Live-cell imaging is a powerful tool to visualize dynamic processes. The examination of fixed cells provides only static pictures, which can lead to misinterpretation and confusion about the process. This work presents a method to study uptake, drug release, and intracellular localization of liposomal nanoparticles in living cells.

Conventional imaging techniques can provide detailed information about cellular processes. However, this information is based on static images in an ...

Encapsulation of Cancer Therapeutic Agent Dacarbazine Using Nanostructured Lipid Carrier

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