Name: preparation and characterization of lipophilic doxorubicin pro-drug micelles
Uploaded: 2016-08-02T15:00:00
Description: Watch this Scientific Journal Video about Preparation and Characterization of Lipophilic Doxorubicin Pro-drug Micelles at JoVE.com

This work was supported by the following grants: NIH-SC3 grant, NSF-PREM grant, Hampton University Faculty Research Grant. We would like to thank Mrs. Michele A. Cochran at Virginia Institute of Marine Science (VIMS) for the use of the particle size analyzer. We would also like to thank Mrs. Corinne R. Ramaley for reviewing the manuscript.

1. Synthesis of DOX-PA
<ol>
	<li>Weigh 390 mg of doxorubicin and 243 mg of palmitic acid hydrazide, and transfer to a round bottom flask.</li>
	<li>Add 150 ml of anhydrous methanol to the flask with a glass syringe. Add 39 &#181;l of trifluoroacetic acid (TFA) with a pipette. Using a magnetic stirrer, stir the reaction mixture for 18 hr at RT in the dark. 
	NOTE: The quantities of reaction materials can be scaled up or down to obtain different amounts of DOX-PA. The ratio of reactants should be ma...

<ol>
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I., Huang, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Doxorubicin+and+lapatinib+combination+nanomedicine+for+treating+resistant+breast+cancer.">Doxorubicin and lapatinib combination nanomedicine for treating resistant breast cancer.</a> Mol Pharm. 11 (8), 2600-2611 (2014).</li><li>Ma, P., Rahima Benhabbour, S., Feng, L., Mumper, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=2'-Behenoyl-paclitaxel+conjugate+containing+lipid+nanoparticles+for+the+treatment+of+metastatic+breast+cancer.">2'-Behenoyl-paclitaxel conjugate containing lipid nanoparticles for the treatment of metastatic breast cancer.</a> Cancer Lett. 334 (2), 253-262 (2013).</li><li>Lundberg, B. B., Risovic, V., Ramaswamy, M., Wasan, K. 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K., Kaddoumi, A., Nazzal, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mixed+micelles+of+PEG(2000)-DSPE+and+vitamin-E+TPGS+for+concurrent+delivery+of+paclitaxel+and+parthenolide:+enhanced+chemosenstization+and+antitumor+efficacy+against+non-small+cell+lung+cancer+(NSCLC)+cell+lines.">Mixed micelles of PEG(2000)-DSPE and vitamin-E TPGS for concurrent delivery of paclitaxel and parthenolide: enhanced chemosenstization and antitumor efficacy against non-small cell lung cancer (NSCLC) cell lines.</a> Eur J Pharm Sci. 46 (1-2), 67-71 (2012).</li><li>Still, W. 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(64), (2012).</li><li>Ulbrich, K., Etrych, T., Chytil, P., Jelinkova, M., Rihova, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HPMA+copolymers+with+pH-controlled+release+of+doxorubicin:+in+vitro+cytotoxicity+and+in+vivo+antitumor+activity.">HPMA copolymers with pH-controlled release of doxorubicin: in vitro cytotoxicity and in vivo antitumor activity.</a> J Controlled Release. 87 (1-3), 33-47 (2003).</li><li>Patil, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cellular+Delivery+of+Doxorubicin+via+pH-Controlled+Hydrazone+Linkage+Using+Multifunctional+Nano+Vehicle+Based+on+Poly(beta-L-Malic+Acid).">Cellular Delivery of Doxorubicin via pH-Controlled Hydrazone Linkage Using Multifunctional Nano Vehicle Based on Poly(beta-L-Malic Acid).</a> Int J Mol Sci. 13 (9), 11681-11693 (2012).</li><li>Hu, X., Liu, S., Huang, Y., Chen, X., Jing, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Biodegradable+block+copolymer-doxorubicin+conjugates+via+different+linkages:+preparation,+characterization,+and+in+vitro+evaluation.">Biodegradable block copolymer-doxorubicin conjugates via different linkages: preparation, characterization, and in vitro evaluation.</a> Biomacromolecules. 11 (8), 2094-2102 (2010).</li><li>Huynh, L., Neale, C., Pomes, R., Allen, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Computational+approaches+to+the+rational+design+of+nanoemulsions,+polymeric+micelles,+and+dendrimers+for+drug+delivery.">Computational approaches to the rational design of nanoemulsions, polymeric micelles, and dendrimers for drug delivery.</a> Nanomedicine. 8 (1), 20-36 (2012).</li><li>Shi, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+drug-specific+nanocarrier+design+for+efficient+anticancer+therapy.">A drug-specific nanocarrier design for efficient anticancer therapy.</a> Nat Commun. 6, 7449 (2015).</li></ol>

In this work, we describe an uncomplicated, rapid film-dispersion method for the preparation of micelles. This method utilizes the self-assembly properties of an amphiphilic polymer (e.g., DSPE-PEG) to form core-shell structured micelles in an aqueous environment. This micelle preparation method has several advantages. 1. It involves a simple formulation process, which avoids the use of complicated size-reduction steps (such as extrusion or homogenization) commonly used in the preparation of liposomes, nanoparti...

Chemotherapy is commonly used to treat various forms of cancers. Most, if not all, chemotherapy drugs have toxic side effects which may vary from manageable minor conditions, such as nausea and diarrhea, to more life threatening conditions. Because most anticancer drugs are toxic, non-selective exposure of these drugs to normal tissue inevitably causes toxicity. Therefore, there is a great need for a therapeutic approach that can selectively deliver drugs into cancer cells. Another challenge with the administration of anticancer drugs is their poor water solubility. Usually, solubilizing agents are needed to formulate these poorly soluble drugs. However, most solubilizing agents, such as dimethyl sulfoxide (DMSO), Cremophor EL, and Polysorbate 80 (Tween 80) may cause liver and kidney toxicity, hemolysis, acute hypersensitivity reactions and peripheral neuropathies.1 Therefore, safe and biocompatible formulations are needed for the clinical use of poorly soluble anticancer drugs. Nanocarriers are promising drug delivery systems for addressing the above challenges. These nanocarriers include liposomes,2 nanoparticles,3 micelles,4-7 polymer-drug conjugates,8 and inorganic materials.9 Several nanomedicine products (e.g., Doxil, Abraxane, and Genexol) have been approved by the regulatory agencies to treat cancer patients.10
Polymeric micelles are promising nano-scale drug delivery carriers, which have been successfully used for the delivery of anticancer drugs.4-7,11,12 Typical polymeric micelles are prepared from amphiphilic polymers through a self-assembly process. The core-shell structured polymeric micelles include a hydrophilic shell and a hydrophobic core. The hydrophilic shell can sterically stabilize micelles and prolong their circulation in blood stream. The hydrophobic core can effectively encapsulate hydrophobic drugs. Because of the small size of micelles (typically less than 200 nm) and long-circulation properties, polymeric micelles are believed to achieve tumor targeting through enhanced permeability and retention (EPR) effects (passive tumor targeting).
Drug loading stability is critical for the tumor targeting ability of micelles. To achieve optimal tumor targeting, micelles should have minimal drug leakage before reaching the tumor site, yet quickly release the drug after entering cancer cells. In addition, formulation stability is also an essential requirement for product development, because formulation stability determines the feasibility of product development, as well as the shelf-life of developed products. Recently, much effort has been made to improve the loading of drugs into delivery carriers. The lipophilic pro-drug approach is a strategy which has been explored to improve drug loading into lipid nanoparticles and emulsions.13,14 The conjugation of lipids with drugs can significantly improve their lipophilicity and enhance loading and retention in the lipophilic components of nanocarriers.
Here, we describe a protocol for preparing lipophilic doxorubicin pro-drug loaded micelles. First, the synthesis procedure for doxorubicin lipophilic pro-drug is described. Then, a protocol for generating micelles with a film-dispersion method is introduced. This method has been successfully used in our previous studies.5 DSPE-PEG was selected as the carrier material for preparing micelles because it has been successfully used for micelle drug delivery.15,16 Finally, we describe several in vitro assays used to characterize micelle formulations and to evaluate anticancer activity.

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	<tbody>
		<tr height="23">
			<td height="23" style="height:23px;width:216px;">DSPE-PEG2K</td>
			<td style="width:191px;">Cordenpharm</td>
			<td style="width:119px;">LP-R4-039</td>
			<td style="width:167px;">&#62;95%</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Doxorubicin</td>
			<td style="width:191px;">LC Laboratories</td>
			<td style="width:119px;">D-4000</td>
			<td>&#62;99%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Palmitic Acid Hydrazide</td>
			<td style="width:191px;">TCI AMERICA&#160;&#160;</td>
			<td style="width:119px;">P000425G</td>
			<td>&#62;98.0%</td>
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			<td height="21" style="height:21px;width:216px;">Methanol</td>
			<td style="width:191px;">ACROS Organics</td>
			<td style="width:119px;">610981000</td>
			<td>Anhydrous</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Methylene chloride&#160;</td>
			<td style="width:191px;">FISHER&#160;</td>
			<td style="width:119px;">D151-4</td>
			<td>99.90%</td>
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			<td height="21" style="height:21px;width:216px;">Methyl sulfoxide-d6</td>
			<td style="width:191px;">ACROS Organics</td>
			<td style="width:119px;">AC320760075</td>
			<td>NMR solvent</td>
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		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Trifluoroacetic Acid&#160;</td>
			<td style="width:191px;">ACROS Organics</td>
			<td style="width:119px;">AC293811000</td>
			<td>99.50%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Silica Gel</td>
			<td style="width:191px;">FISHER&#160;</td>
			<td style="width:119px;">L-7446</td>
			<td>230-400 mesh</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">BAKER FLEX TLC PLATES&#160;</td>
			<td style="width:191px;">FISHER&#160;</td>
			<td style="width:119px;">NC9990129</td>
			<td></td>
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			<td height="21" style="height:21px;width:216px;">DPBS</td>
			<td style="width:191px;">Sigma-Aldrich</td>
			<td style="width:119px;">D8537</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">DU 145&#160; Prostate Cancer Cells</td>
			<td style="width:191px;">ATCC</td>
			<td style="width:119px;">HTB-81</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">MTT</td>
			<td style="width:191px;">ACROS Organics</td>
			<td style="width:119px;">158990050</td>
			<td>98%</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">RPMI 1640 Medium</td>
			<td style="width:191px;">MEDIATECH INC&#160;</td>
			<td style="width:119px;">10041CV</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Antibiotic-Antimycotic&#160;</td>
			<td style="width:191px;">LIFE TECHNOLOGIES&#160;</td>
			<td style="width:119px;">15240062</td>
			<td>100x stock solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Fetal Bovine Serum</td>
			<td style="width:191px;">LIFE TECHNOLOGIES&#160;</td>
			<td style="width:119px;">10437077</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Nuclear Magnetic Resonance Spectroscopy</td>
			<td style="width:191px;">Varian, Inc</td>
			<td style="width:119px;"></td>
			<td>300 NMR&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">B&#252;chi R-3 Rotavapor</td>
			<td style="width:191px;">Buchi</td>
			<td style="width:119px;">1103022V1&#160;</td>
			<td>Rotary evaporator</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Ultrasonic Bath</td>
			<td style="width:191px;">BRANSON ULTRASONICS CORPORATION&#160;</td>
			<td style="width:119px;">CPX952318R</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">UV-VIS spectrometer Biomate 3</td>
			<td style="width:191px;">Thermo Spectronic</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Zetasizer Nano ZS90&#160;</td>
			<td style="width:191px;">Malvern Instruments</td>
			<td style="width:119px;"></td>
			<td>Particle Size Analyer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Microplate Spectrophotometer&#160;</td>
			<td style="width:191px;">Rio-Rad</td>
			<td style="width:119px;">Benchmark Plus&#160;</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Cell Culture Incubator</td>
			<td style="width:191px;">Napco</td>
			<td style="width:119px;">CO2 6000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Biological Safety Cabinet</td>
			<td style="width:191px;">Nuaire</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SigmaPlot&#160;</td>
			<td style="width:191px;">Systat Software, Inc.</td>
			<td style="width:119px;"></td>
			<td>Analytical Software</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">96-Well Cell Culture Plate</td>
			<td style="width:191px;">Becton Dickinson</td>
			<td style="width:119px;">353072</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Trypsin&#160; 0.25%</td>
			<td style="width:191px;">Corning Cellgro</td>
			<td style="width:119px;">25-053-CI</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

Figure 1 shows the synthesis scheme of DOX-PA. DOX-PA was synthesized by conjugation of palmitic acid with doxorubicin through a pH-sensitive hydrazone bond. A slight excess of palmitic acid hydrazide was used to facilitate the completion of the reaction. This reaction method has a very high efficiency and only a small amount of doxorubicin remained after an 18 hr reaction (Figure 2). The yield was approximately 88%. At the end of the reaction, DOX-PA was...

Watch this Scientific Journal Video about Preparation and Characterization of Lipophilic Doxorubicin Pro-drug Micelles at JoVE.com

Preparation and Characterization of Lipophilic Doxorubicin Pro-drug Micelles

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Growth and Characterization of Irradiated Organoids from Mammary Glands

Organoids derived from the digested tissue are multicellular three-dimensional (3D) constructs that better recapitulate in vivo conditions than cell ...

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 ...

Focused Ion Beam Lithography to Etch Nano-architectures into Microelectrodes

With advances in electronics and fabrication technology, intracortical microelectrodes have undergone substantial improvements enabling the production of ...

Generation and Quantitative Characterization of Functional and Polarized Biliary Epithelial Cysts

Cholangiocytes, the epithelial cells that line up the bile ducts in the liver, oversee bile formation and modification. In the last twenty years, in the ...

Temperature-Controlled Assembly and Characterization of a Droplet Interface Bilayer

The droplet interface bilayer (DIB) method for assembling lipid bilayers (i.e., DIBs) between lipid-coated aqueous droplets in oil offers key benefits ...