Name: microwave-driven synthesis of iron oxide nanoparticles for fast detection of atherosclerosis
Uploaded: 2016-03-22T14:00:00
Description: Watch this Scientific Journal Video about Microwave-driven Synthesis of Iron Oxide Nanoparticles for Fast Detection of Atherosclerosis at JoVE.com

This study is supported by a grant from Comunidad de Madrid (S2010/BMD-2326, Inmunothercan-CM), by Fundacio La Marato de TV3 (70/C/2012) and by and by Spanish Economy Ministry (MAT2013-47303 P).

1. Preparation of Reagents
<ol>
	<li>Prepare 1 mM HEPES Buffer dissolving 23.8 mg of HEPES in 100 ml of distilled water. Adjust the pH to 7.</li>
	<li>Prepare 10% NaHSO3 dissolving 10 g of NaHSO3 in 100 ml of distilled water. Stir the mixture for 15 min.</li>
	<li>Prepare NaOH solution dissolving 1 g of NaOH in 100 ml of water. Stir for 10 min.</li>
	<li>Prepare 10 mM Phosphate buffer dissolving 600 mg of NaH2PO4 in 1 L of water. Add carefully 0.34 ml of phosphoric acid and S...

<ol>
	<li>Patel, D. N., Bailey, S. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nanotechnology+in+cardiovascular+medicine.">Nanotechnology in cardiovascular medicine.</a> Catheter. Cardiovasc. Interv. Off. J. Soc. Card. Angiogr. Interv. 69, 643-654 (2007).</li><li>Zhao, X., Zhao, H., Chen, Z., Lan, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ultrasmall+superparamagnetic+iron+oxide+nanoparticles+for+magnetic+resonance+imaging+contrast+agent.">Ultrasmall superparamagnetic iron oxide nanoparticles for magnetic resonance imaging contrast agent.</a> J. Nanosci. Nanotechnol. 14, 210-220 (2014).</li><li>Lee, D. E., 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=Multifunctional+nanoparticles+for+multimodal+imaging+and+theragnosis.">Multifunctional nanoparticles for multimodal imaging and theragnosis.</a> Chem. Soc. Rev. 41, 2656 (2012).</li><li>Osborne, E. A., 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=Rapid+microwave-assisted+synthesis+of+dextran-coated+iron+oxide+nanoparticles+for+magnetic+resonance+imaging.">Rapid microwave-assisted synthesis of dextran-coated iron oxide nanoparticles for magnetic resonance imaging.</a> Nanotechnology. 23, (2012).</li><li>Pellico, J., 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=Microwave-driven+synthesis+of+bisphosphonate+nanoparticles+allows+in+vivo+visualisation+of+atherosclerotic+plaque.">Microwave-driven synthesis of bisphosphonate nanoparticles allows in vivo visualisation of atherosclerotic plaque.</a> RSC Adv. 5, 1661-1665 (2015).</li><li>Lin, M. M., Kim, D. K., El Haj, A. J., Dobson, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+superparamagnetic+iron+oxide+nanoparticles+(SPIONS)+for+translation+to+clinical+applications.">Development of superparamagnetic iron oxide nanoparticles (SPIONS) for translation to clinical applications.</a> IEEE Trans. Nanobioscience. 7, 298-305 (2008).</li><li>Gupta, A. K., Gupta, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+and+surface+engineering+of+iron+oxide+nanoparticles+for+biomedical+applications.">Synthesis and surface engineering of iron oxide nanoparticles for biomedical applications.</a> Biomaterials. 26, 3995-4021 (2005).</li><li>Liu, F., Laurent, S., Fattahi, H., Vander Elst, L., Muller, R. N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Superparamagnetic+nanosystems+based+on+iron+oxide+nanoparticles+for+biomedical+imaging.">Superparamagnetic nanosystems based on iron oxide nanoparticles for biomedical imaging.</a> Nanomed. 6, 519-528 (2011).</li><li>Carenza, E., 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=Rapid+synthesis+of+water-dispersible+superparamagnetic+iron+oxide+nanoparticles+by+a+microwave-assisted+route+for+safe+labeling+of+endothelial+progenitor+cells.">Rapid synthesis of water-dispersible superparamagnetic iron oxide nanoparticles by a microwave-assisted route for safe labeling of endothelial progenitor cells.</a> Acta Biomater. 10, 3775-3785 (2014).</li><li>Osborne, E. A., 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=Rapid+microwave-assisted+synthesis+of+dextran-coated+iron+oxide+nanoparticles+for+magnetic+resonance+imaging.">Rapid microwave-assisted synthesis of dextran-coated iron oxide nanoparticles for magnetic resonance imaging.</a> Nanotechnology. 23, 215602 (2012).</li><li>Gatti, D., Rossini, M., Viapiana, O., Idolazzi, L., Adami, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+development+of+neridronate:+potential+for+new+applications.">Clinical development of neridronate: potential for new applications.</a> Ther. Clin. Risk Manag. 9, 139-147 (2013).</li><li>Drake, M. T., Clarke, B. L., Khosla, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Bisphosphonates:+mechanism+of+action+and+role+in+clinical+practice.">Bisphosphonates: mechanism of action and role in clinical practice.</a> Mayo Clin Proc. 83, 1032-1045 (2008).</li><li>Devogelaer, J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Treatment+of+bone+diseases+with+bisphosphonates,+excluding+osteoporosis.">Treatment of bone diseases with bisphosphonates, excluding osteoporosis.</a> Curr. Opin. Rheumatol. 12, 331-335 (2000).</li><li>Pascu, O., 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=Surface+Reactivity+of+Iron+Oxide+Nanoparticles+by+Microwave-Assisted+Synthesis;+Comparison+with+the+Thermal+Decomposition+Route.">Surface Reactivity of Iron Oxide Nanoparticles by Microwave-Assisted Synthesis; Comparison with the Thermal Decomposition Route.</a> J. Phys. Chem. C. 116, 15108-15116 (2012).</li><li>Sun, S., Zeng, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Size-Controlled+Synthesis+of+Magnetite+Nanoparticles.">Size-Controlled Synthesis of Magnetite Nanoparticles.</a> J. Am. Chem. Soc. 124, 8204-8205 (2002).</li><li>Hyeon, T., Lee, S. S., Park, J., Chung, Y., Na, H. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Synthesis+of+highly+crystalline+and+monodisperse+maghemite+nanocrystallites+without+a+size-selection+process.">Synthesis of highly crystalline and monodisperse maghemite nanocrystallites without a size-selection process.</a> J. Am. Chem. Soc. 123, 12798-12801 (2001).</li><li>Herranz, F., Morales, M. P., Roca, A. G., Vilar, R., Ruiz-Cabello, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+method+for+the+aqueous+functionalization+of+superparamagnetic+Fe+2+O+3+nanoparticles.">A new method for the aqueous functionalization of superparamagnetic Fe 2 O 3 nanoparticles.</a> Contrast Media Mol. Imaging. 3, 215-222 (2008).</li><li>Herranz, F., Morales, M. P., Roca, A. G., Desco, M., Ruiz-Cabello, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+method+for+the+rapid+synthesis+of+water+stable+superparamagnetic+nanoparticles.">A new method for the rapid synthesis of water stable superparamagnetic nanoparticles.</a> Chem. Weinh. Bergstr. Ger. 14, 9126-9130 (2008).</li><li>Herranz, F., 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=Superparamagnetic+iron+oxide+nanoparticles+conjugated+to+a+grass+pollen+allergen+and+an+optical+probe.">Superparamagnetic iron oxide nanoparticles conjugated to a grass pollen allergen and an optical probe.</a> Contrast Media Mol. Imaging. 7, 435-439 (2012).</li></ol>

Iron oxide nanoparticles (IONP) are one of the most important nanomaterials and it has been used for different applications from long time ago. The use of these materials as contrast agent for magnetic resonance imaging (MRI) is a well-established field. However, the routes of synthesis often take several time and the setting is complicated. Due to dramatically reduce reaction times and enhances reproducibility the use of microwave-driven synthesis seems to be a good alternative for the production of high quality nanopar...

Atherosclerosis is a multifactorial chronic inflammatory disease of the arterial wall resulting from a deregulated lipid metabolism and a defective inflammatory response. Due to the prevalence and the economical and social costs of this and related cardiovascular diseases there is a growing interest in addressing the pathology with new tools, of which nanotechnology is one of the most promising.1-3 However there are very few examples of fast production and characterization of probes which is basic for translation to the clinic.4 In this protocol we use a microwave synthesis of iron oxide nanoparticle for further functionalization with a bisphosphonate and in vivo detection of atherosclerosis in ApoE-/- mice in 1 hr.5&#160; Iron oxide nanoparticles (IONP) are a well-known nanomaterial and its use as a contrast agent for Magnetic Resonance Imaging (MRI) has been established for the detection of different diseases in the last years.6-8
Microwave synthesis (MWS), allows synthesizing nanoparticles in extremely short times with high reproducibility and enhanced yields.9,10 In our protocol we obtain IONP with plaque targeting capabilities in three steps. The final one is the attachment of an aminobisphosphonate, Neridronate, which is key in our strategy due to its calcium-binding properties. Due to their natural analogue pyrophosphate (PPi), Neridronate has been used in the treatment of Osteogenesis Imperfecta (OI) and Paget&#39;s disease of bone (PDB) for their high affinity towards bone mineral.11-13
The three steps of the protocol are summarized in scheme 1. Steps one and two are carried out using microwave technology. First step provide oleic acid-coated iron oxide nanoparticles (OA-IONP) by a modification of published methods.14 The protocol is an adaptation to microwave synthesis of the traditional thermal decomposition synthesis.15,16 A mixture containing Fe(acac)3, oleic acid, oleylamine and 1,2-dodecanediol is dissolved in benzyl alcohol and subjected at two heating processes. Purification is carried out washing with EtOH and collecting the particles with a Nd-Fe-B magnet to eliminate the excess of surfactants in the supernatant. Then, OA-IONP are stabilized in CHCl3. As expected, due to the very fast heating, anticipated results showed that the nanoparticles synthesized by microwave are smaller in terms of core (3.7 &#177; 0.8 nm) and hydrodynamic size (7.5 nm) in comparison with traditional thermal decomposition; however, nanoparticles still present an excellent crystallinity.
The second step consists in a direct chemical modification of the double bond, present in the oleic acid, using a strong oxidant like KMnO4, the original methodology developed in our group was modified for MW conditions.17 A first stage forms the complexes between MnO4- and the double bond. Then, a second stage in acidic conditions, produce the cleavage of the oleic acid molecule giving Azelaic acid-IONP. After these two stages of 9 min each, the sample is purified, first washing with NaHSO3 1% to reduce the excess of MnO4- to MnO2 and then with NaOH 1% to neutralize the acid.
After the purification step, Azelaic-IONP are stabilized in 10 mM phosphate buffer pH = 7.2. This buffer is the best environment for the colloidal stability of the particles similarly to what happened in the original, thermal reaction.18 The use of microwave for the direct oxidation of the double bond contained in OA-IONP is a very good example of the advantages of using this technology in the synthesis of nanoparticles. With the classical method the reaction takes 24 hr, the utilization of microwave decrease the reaction time to 18 min. Moreover, the microwave-driven protocol shows an excellent reproducibility giving nanoparticles with 30 &#177; 5 nm of hydrodynamic size after 4 repetitions. Apart of the change in the hydrodynamic size, the zeta potential is a good parameter to quickly check the successful of the reaction. Due to the presence of the new carboxylic groups in Azelaic-IONP, the value for the zeta potential is around -44 mV, very similar to the value obtained by the thermal approach.
For the attachment of neridronate to Azelaic-IONP, traditional EDC/sulfo-NHS conjugation is used.19 This synthetic approach is well-established since employing an activated carboxylate with the sulfo-NHS ensures colloidal stability during the reaction. After the elimination of phosphate buffer the reaction with neridronate is carried out in 1 mM HEPES buffer (pH ~7). The reaction renders Neridronate-IONP with a hydrodynamic size of 40 &#177; 4 nm in a narrow size distribution and -24.1 mV of zeta-potential.
The procedure is described for fast synthesis of IONP for in vivo visualization of atherosclerotic plaque although the feasibility of the method allows the attachment of any peptide/antibody with free amines, using the same conditions, for different purposes within T2-weighted contrast agent MRI field.

<table border="0" cellpadding="0" cellspacing="0" width="1107">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Microwave Explorer/Discover Hybrid-12</td>
			<td style="width:176px;">CEM Corporation, USA</td>
			<td style="width:225px;"></td>
			<td style="width:311px;">Any microwave for chemical synthesis can be used</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Disposable PD-10 desalting columns&#160;</td>
			<td>GE Healthcare life sciences</td>
			<td>17-0851-01</td>
			<td>Any size exclusion column will work</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Amicon&#174;Ultra-0.5 ml&#160;</td>
			<td>Merck Millipore Ltd</td>
			<td style="width:225px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Calibrated pH meter&#160;</td>
			<td>SI analytics</td>
			<td>285105127</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Neodymium magnet&#160;</td>
			<td>Aiman Gz</td>
			<td>ND010B</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Vortex Genius 3&#160;</td>
			<td>IKA</td>
			<td>3340000</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">ZetaSizer Nano ZS&#160;</td>
			<td>Malvern Instruments</td>
			<td style="width:225px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Standard (macro) cell Optical glass&#160;</td>
			<td>Labbox</td>
			<td>11718</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Zetasizer nanoseries disponsable folded capillary cells DTS1070</td>
			<td>Malvern</td>
			<td style="width:225px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:395px;">Bruker Minispec mq60</td>
			<td style="width:176px;">Bruker</td>
			<td style="width:225px;"></td>
			<td></td>
		</tr>
	</tbody>
</table>

microwave-driven synthesis of iron oxide nanoparticles for fast detection of atherosclerosis

A fast and reproducible microwave-driven protocol has been developed for the synthesis of neridronate-functionalized nanoparticles. Starting from the synthesis of hydrophobic nanoparticles, our method is based on an adaptation from thermal decomposition method to microwave driven synthesis. The new methodology produces a decrease in the reaction times in comparison with traditional procedures. Moreover, the use of the microwave technology increases the reproducibility of the reactions, something important from the point of view of clinical applications. The novelty of this iron oxide nanoparticle is the attachment of Neridronate. The use of this molecule leads a bisphosphonate moiety towards the outside of the nanoparticle that provides Ca2+ binding properties in vitro and selective accumulation in vivo in the atheroma plaque. The protocol allows the synthesis and plaque detection in about 3 hr since the initial synthesis from organic precursors. Their accumulation in the atherosclerotic area in less than 1 hr provides a contrast agent particularly suitable for clinical applications.

In this protocol, the synthesis of three different IONP is described. Starting from hydrophobic OA-IONP, aqueous stable nanoparticles are obtained with the help of microwave-driven synthesis. All nanoparticles presented ultra-small hydrodynamic size (Dh &#60;50 nm) in a very narrow size distribution (Figure 1c). The use of microwave technology renders ultra-small nanoparticles in terms of core sizes. Since microwave produce a fast heating, the rate of the nucleation incre...

Watch this Scientific Journal Video about Microwave-driven Synthesis of Iron Oxide Nanoparticles for Fast Detection of Atherosclerosis at JoVE.com

Microwave-driven Synthesis of Iron Oxide Nanoparticles for Fast Detection of Atherosclerosis

Microwave technology enables extremely fast synthesis of iron oxide nanoparticles for atherosclerosis plaque characterization. The use of an aminobisphosphonate in the external side of the nanoparticle provides a fast accumulation in the atherosclerotic area.

A fast and reproducible microwave-driven protocol has been developed for the synthesis of neridronate-functionalized nanoparticles. Starting from the ...

The overall goal of this protocol is the use of microwave technology for the rapid synthesis and functionalization of iron oxide nanoparticles with a bisphosphonate moiety for fast detection by MRI of atherosclerosis in mice models. The use of microwave technology in the synthesis and functionalization of iron oxide nanoparticles is still limited. However, we demonstrate how high quality nanoparticles and extremely fast protocols can be developed.The main advantage of this technique is that in extremely short times, high quality functionalized nanoparticles can be produced and used for catheterization of atherosclerosis plaque targeting microcalcifications. To begin this procedure, add 0.5 grams of iron 3-acetylacetenate, 1.4 milliliters of oleic acid, 0.6 milliliters of oleylamine, and 1.19 grams of 1, 2-Hexadodecanediol to a microwave-adapted flask. Add 10 milliliters of phenyl ether carefully down the flask wall using a graduated pipette.Following this, place the flask in a microwave reactor and start the microwave protocol by loading a dynamic study in the microwave. After the reaction is complete, and the flask has cooled to room temperature, transfer the reaction mixture to an Erlenmeyer flask using a glass pipette and add 10 milliliters of 98 percent ethanol. Place the flask on top of a neodymium niobium boron magnet and remove the supernatant with a glass pipette after 5 minutes.Next, add 10 milliliters of ethanol to the flask. Sonicate the sample at 40 kilohertz for two minutes at room temperature. When finished, place the sample on the magnet and remove the supernatant.Disperse the oleic acid coated nanoparticles in 30 milliliters of chloroform and sonicate at 40 kilohertz for five minutes at room temperature. Following sonication, transfer 0.5 milliliters of the nanoparticles in a glass cuvette and add 0.5 milliliters of chloroform. Check the hydrodynamic size in a zetasizer per the manufacturer's instructions.At this point, dissolve 44.3 milligrams of potassium permanganate and 150.4 milligrams of benzoyl trimethyl ammonium chloride in a three to two mixture of water and chloroform. Add the resultant solution to a 5 milliliter Aliquat of the oleic-acid coated nanoparticles in a microwave-adapted flask. Start the microwave protocol for azelaic acid nanoparticles by setting the temperature to 105 degrees Celsius, the time to nine minutes, the pressure to 250 psi, and the power to 300 watts.Following this, add 10 milliliters of pH 2.9 phosphate buffer to the flask. After repeating the microwave protocol, and removing the supernatant, add 10 milliliters of water to the flask and transfer the mixture to an Erlenmeyer flask. The most critical step is purification of azelaic acid nanoparticles.Next, add 5 milliliters of 10 percent sodium bisulphate to the Erlenmeyer flask and sonicate at 40 kilohertz for two minutes at 25 degrees Celsius. After collecting the particles, and removing the supernatant, wash the nanoparticles three more times with 1 percent sodium hydroxide. Redisperse the particles in 5 milliliters of pH 7.2 phosphate buffer.To check the hydrodynamic size and zeta potential, transfer 0.7 milliliters of the azelaic acid nanoparticles to a disposable, folded capillary cell and place it in the zetasizer for analysis. Add 12 milligrams of EDC and 15 milligrams of sulfo-NHS in a centrifuge tube with a 2 milliliter Aliquat of the azelaic acid nanoparticles. Vortex the mixture at room temperature for 35 minutes.After placing a magnet below the centrifuge tube to destabilize the nanoparticles, aspirate the supernatant and wash the particles with 1.5 milliliters of 1 millimolar hepes buffer. Then, add 5 milligrams of neridronate and vortex the mixture for two hours. Separate the nanoparticles with a magnet and wash with 1 millimolar hepes buffer.Finally, disperse the neridronate nanoparticles in 2 milliliters of 1 millimolar hepes buffer. To check the hydrodynamic size and zeta potential, add 0.7 milliliters of the neridronate nanoparticles to a disposable folded capillary cell and place it in the zetsizer for analysis. All nanoparticles presented small hydrodynamic size in a very narrow size distribution.The particles present excellent crystallinity as shown in the TEM images. Additionally, the same results for hydrodynamic size and distribution were obtained after four repetitions of the synthesis, demonstrating one of the most important aspects of the microwave approach, its reproducability. The calcium ion binding properties due to bisphosphonates present in the neridronate nanoparticles were checked by relaxometry and demonstrated that T2 relaxation time increments linearly with the calcium ion amount and incubation time due to the formation of nanoparticle clusters whereas nanoparticles without calcium ion remained stable.In vivo MRI experiments were performed in 48-week old apoe knockout mice and at one hour post injection, the signal from the plaque was hypointense in comparison to the basal images. Additionally, the plaque to muscle ratio was significantly different between the basal and one hour post injection images. The signal in the liver was also monitored after injection of the neridronate nanoparticles which were completely cleared from circulation after 20 minutes, confirming the selective accumulation of these nanoparticles towards atherosclerotic plaque.Ex vivo imaging and histology were performed and imaging of aortas, with and without nanoparticles, showed differences in the signal intensity in agreement with the in vivo experiments. Once mastered, the microwave technology allows for the synthesis characterization and plaque detection in a total time of 3 hours if properly performed. Another advantage of this method is that, with a small modification other imaging techniques, like thermography can be performed, in order to answer additional questions like quantification of atherosclerosis.After its development, this technique paved the way for researchers in the field of cardiovascular imaging to explore the early diagnosis of atherosclerosis with an experimental setup that can be easily adapted to clinical needs. After watching this video, you should have a good understanding of how to produce hydrophilic iron oxide nanoparticles with microwave and its application in cardiovascular imaging. Don't forget that working with microwave ovens can be hazardous depending on the oven used, and precautions such as pressure control of the cistern should always be taken while performing this procedure.

microwave-driven-synthesis-iron-oxide-nanoparticles-for-fast

Research

JoVE Journal

Bioengineering

High-throughput Synthesis of Carbohydrates and Functionalization of Polyanhydride Nanoparticles

Transdisciplinary approaches involving areas such as material design, nanotechnology, chemistry, and immunology have to be utilized to rationally design efficacious vaccines carriers. Nanoparticle-based platforms can prolong the persistence of vaccine antigens, which could improve vaccine immunogenicity1. Several biodegradable polymers have been studied as vaccine delivery vehicles1; in particular, polyanhydride particles have demonstrated the ability to provide sustained release of stable protein antigens and to activate antigen presenting cells and modulate immune responses2-12.
The molecular design of these vaccine carriers needs to integrate the rational selection of polymer properties as well as the incorporation of appropriate targeting agents. High throughput automated fabrication of targeting ligands and functionalized particles is a powerful tool that will enhance the ability to study a wide range of properties and will lead to the design of reproducible vaccine delivery devices.
The addition of targeting ligands capable of being recognized by specific receptors on immune cells has been shown to modulate and tailor immune responses10,11,13 C-type lectin receptors (CLRs) are pattern recognition receptors (PRRs) that recognize carbohydrates present on the surface of pathogens. The stimulation of immune cells via CLRs allows for enhanced internalization of antigen and subsequent presentation for further T cell activation14,15. Therefore, carbohydrate molecules play an important role in the study of immune responses; however, the use of these biomolecules often suffers from the lack of availability of structurally well-defined and pure carbohydrates. An automation platform based on iterative solution-phase reactions can enable rapid and controlled synthesis of these synthetically challenging molecules using significantly lower building block quantities than traditional solid-phase methods16,17.
Herein we report a protocol for the automated solution-phase synthesis of oligosaccharides such as mannose-based targeting ligands with fluorous solid-phase extraction for intermediate purification. After development of automated methods to make the carbohydrate-based targeting agent, we describe methods for their attachment on the surface of polyanhydride nanoparticles employing an automated robotic set up operated by LabVIEW as previously described10. Surface functionalization with carbohydrates has shown efficacy in targeting CLRs10,11 and increasing the throughput of the fabrication method to unearth the complexities associated with a multi-parametric system will be of great value (Figure 1a).

In this article, a high throughput method is presented for the synthesis of oligosaccharides and their attachment to the surface of polyanhydride nanoparticles for further use in targeting specific receptors on antigen presenting cells.

Transdisciplinary approaches involving areas such as material design, nanotechnology, chemistry, and immunology have to be utilized to rationally design ...

Harmonic Nanoparticles for Regenerative Research

In this visualized experiment, protocol details are provided for in vitro labeling of human embryonic stem cells (hESC) with second harmonic generation nanoparticles (HNPs). The latter are a new family of probes recently introduced for labeling biological samples for multi-photon imaging. HNPs are capable of doubling the frequency of excitation light by the nonlinear optical process of second harmonic generation with no restriction on the excitation wavelength.
Multi-photon based methodologies for hESC differentiation into cardiac clusters (maintained as long term air-liquid cultures) are presented in detail. In particular, evidence on how to maximize the intense second harmonic (SH) emission of isolated HNPs during 3D monitoring of beating cardiac tissue in 3D is shown. The analysis of the resulting images to retrieve 3D displacement patterns is also detailed.

Protocol details are provided for in vitro labeling human embryonic stem cells with second harmonic generating nanoparticles. Methodologies for hESC investigation by multi-photon microscopy and their differentiation into cardiac clusters are also presented.

In this visualized experiment, protocol details are provided for in vitro labeling of human embryonic stem cells (hESC) with second harmonic generation ...

Fabrication of a Functionalized Magnetic Bacterial Nanocellulose with Iron Oxide Nanoparticles

In this study, bacterial nanocellulose (BNC) produced by the bacteria Gluconacetobacter xylinus is synthesized and impregnated in situ with iron oxide nanoparticles (IONP) (Fe3O4) to yield a magnetic bacterial nanocellulose (MBNC). The synthesis of MBNC is a precise and specifically designed multi-step process. Briefly, bacterial nanocellulose (BNC) pellicles are formed from preserved G. xylinus strain according to our experimental requirements of size and morphology. A solution of iron(III) chloride hexahydrate (FeCl3&#183;6H2O) and iron(II) chloride tetrahydrate (FeCl2&#183;4H2O) with a 2:1 molar ratio is prepared and diluted in deoxygenated high purity water. A BNC pellicle is then introduced in the vessel with the reactants. This mixture is stirred and heated at 80 &#176;C in a silicon oil bath and ammonium hydroxide (14%) is then added by dropping to precipitate the ferrous ions into the BNC mesh. This last step allows forming in situ magnetite nanoparticles (Fe3O4) inside the bacterial nanocellulose mesh to confer magnetic properties to BNC pellicle. A toxicological assay was used to evaluate the biocompatibility of the BNC-IONP pellicle. Polyethylene glycol (PEG) was used to cover the IONPs in order to improve their biocompatibility. Scanning electron microscopy (SEM) images showed that the IONP were located preferentially in the fibril interlacing spaces of the BNC matrix, but some of them were also found along the BNC ribbons. Magnetic force microscope measurements performed on the MBNC detected the presence magnetic domains with high and weak intensity magnetic field, confirming the magnetic nature of the MBNC pellicle. Young&#39;s modulus values obtained in this work are also in a reasonable agreement with those reported for several blood vessels in previous studies.

Here, we present a protocol to make a bacterial nanocellulose (BNC) magnetic for applications in damaged blood vessel reconstruction. The BNC was synthesized by G. xylinus strain. On the other hand, magnetization of the BNC was realized through in situ precipitation of Fe2+ and Fe3+ ferrous ions inside the BNC mesh.

In this study, bacterial nanocellulose (BNC) produced by the bacteria Gluconacetobacter xylinus is synthesized and impregnated in situ with iron oxide ...

Cell Labeling and Targeting with Superparamagnetic Iron Oxide Nanoparticles

Targeted delivery of cells and therapeutic agents would benefit a wide range of biomedical applications by concentrating the therapeutic effect at the target site while minimizing deleterious effects to off-target sites. Magnetic cell targeting is an efficient, safe, and straightforward delivery technique. Superparamagnetic iron oxide nanoparticles (SPION) are biodegradable, biocompatible, and can be endocytosed into cells to render them responsive to magnetic fields. The synthesis process involves creating magnetite (Fe3O4) nanoparticles followed by high-speed emulsification to form a poly(lactic-co-glycolic acid) (PLGA) coating. The PLGA-magnetite SPIONs are approximately 120 nm in diameter including the approximately 10 nm diameter magnetite core. When placed in culture medium, SPIONs are naturally endocytosed by cells and stored as small clusters within cytoplasmic endosomes. These particles impart sufficient magnetic mass to the cells to allow for targeting within magnetic fields. Numerous cell sorting and targeting applications are enabled by rendering various cell types responsive to magnetic fields. SPIONs have a variety of other biomedical applications as well including use as a medical imaging contrast agent, targeted drug or gene delivery, diagnostic assays, and generation of local hyperthermia for tumor therapy or tissue soldering.

Targeted cell delivery is useful in a variety of biomedical applications. The goal of this protocol is to use superparamagnetic iron oxide nanoparticles (SPION) to label cells and thereby enable magnetic cell targeting approaches for a high degree of control over cell delivery and localization.

Targeted delivery of cells and therapeutic agents would benefit a wide range of biomedical applications by concentrating the therapeutic effect at the ...

Identification of Metal Oxide Nanoparticles in Histological Samples by Enhanced Darkfield Microscopy and Hyperspectral Mapping

Nanomaterials are increasingly prevalent throughout industry, manufacturing, and biomedical research. The need for tools and techniques that aid in the identification, localization, and characterization of nanoscale materials in biological samples is on the rise. Currently available methods, such as electron microscopy, tend to be resource-intensive, making their use prohibitive for much of the research community. Enhanced darkfield microscopy complemented with a hyperspectral imaging system may provide a solution to this bottleneck by enabling rapid and less expensive characterization of nanoparticles in histological samples. This method allows for high-contrast nanoscale imaging as well as nanomaterial identification. For this technique, histological tissue samples are prepared as they would be for light-based microscopy. First, positive control samples are analyzed to generate the reference spectra that will enable the detection of a material of interest in the sample. Negative controls without the material of interest are also analyzed in order to improve specificity (reduce false positives). Samples can then be imaged and analyzed using methods and software for hyperspectral microscopy or matched against these reference spectra in order to provide maps of the location of materials of interest in a sample. The technique is particularly well-suited for materials with highly unique reflectance spectra, such as noble metals, but is also applicable to other materials, such as semi-metallic oxides. This technique provides information that is difficult to acquire from histological samples without the use of electron microscopy techniques, which may provide higher sensitivity and resolution, but are vastly more resource-intensive and time-consuming than light microscopy.

Enhanced darkfield microscopy and hyperspectral imaging with spectral mapping enable screening, localization, and identification of nanoscale materials in histological samples with improved speed and accuracy over traditional methods. The goal of this paper is to provide methods for darkfield imaging and hyperspectral mapping of metal oxide nanoparticles in histological samples.

Nanomaterials are increasingly prevalent throughout industry, manufacturing, and biomedical research. The need for tools and techniques that aid in the ...

Fast Enzymatic Processing of Proteins for MS Detection with a Flow-through Microreactor

The vast majority of mass spectrometry (MS)-based protein analysis methods involve an enzymatic digestion step prior to detection, typically with trypsin. This step is necessary for the generation of small molecular weight peptides, generally with MW &#60; 3,000-4,000 Da, that fall within the effective scan range of mass spectrometry instrumentation. Conventional protocols involve O/N enzymatic digestion at 37 &#186;C. Recent advances have led to the development of a variety of strategies, typically involving the use of a microreactor with immobilized enzymes or of a range of complementary physical processes that reduce the time necessary for proteolytic digestion to a few minutes (e.g., microwave or high-pressure). In this work, we describe a simple and cost-effective approach that can be implemented in any laboratory for achieving fast enzymatic digestion of a protein. The protein (or protein mixture) is adsorbed on C18-bonded reversed-phase high performance liquid chromatography (HPLC) silica particles preloaded in a capillary column, and trypsin in aqueous buffer is infused over the particles for a short period of time. To enable on-line MS detection, the tryptic peptides are eluted with a solvent system with increased organic content directly in the MS ion source. This approach avoids the use of high-priced immobilized enzyme particles and does not necessitate any aid for completing the process. Protein digestion and complete sample analysis can be accomplished in less than ~3 min and ~30 min, respectively.

A quick protocol for proteolytic digestion with an in-house built flow-through tryptic microreactor coupled to an electrospray ionization (ESI) mass spectrometer is presented. The fabrication of the microreactor, the experimental setup and the data acquisition process are described.

The vast majority of mass spectrometry (MS)-based protein analysis methods involve an enzymatic digestion step prior to detection, typically with trypsin. ...

Synthesis of Cationized Magnetoferritin for Ultra-fast Magnetization of Cells

Many important biomedical applications, such as cell imaging and remote manipulation, can be achieved by labeling cells with superparamagnetic iron oxide nanoparticles (SPIONs). Achieving sufficient cellular uptake of SPIONs is a challenge that has traditionally been met by exposing cells to elevated concentrations of SPIONs or by prolonging exposure times (up to 72 hr). However, these strategies are likely to mediate toxicity. Here, we present the synthesis of the protein-based SPION magnetoferritin as well as a facile surface functionalization protocol that enables rapid cell magnetization using low exposure concentrations. The SPION core of magnetoferritin consists of cobalt-doped iron oxide with an average particle diameter of 8.2 nm mineralized inside the cavity of horse spleen apo-ferritin. Chemical cationization of magnetoferritin produced a novel, highly membrane-active SPION that magnetized human mesenchymal stem cells (hMSCs) using incubation times as short as one minute and iron concentrations as lows as 0.2 mM.

A protocol for the synthesis and cationization of cobalt-doped magnetoferritin is presented, as well as a method to rapidly magnetize stem cells with cationized magnetoferritin.

Many important biomedical applications, such as cell imaging and remote manipulation, can be achieved by labeling cells with superparamagnetic iron oxide ...

Production of Metal Nanoparticles by Pulsed Laser-ablation in Liquids: A Tool for Studying the Antibacterial Properties of Nanoparticles

The emergence of multidrug-resistant bacteria is a global clinical concern leading some to speculate about our return to a "pre-antibiotics" era of medicine. In addition to efforts to identify novel small-molecule antimicrobial drugs, there has been great interest in the use of metal nanoparticles as coatings for medical devices, wound dressings, and consumer packaging, due to their antimicrobial properties. The wide variety of methods available for nanoparticle synthesis results in a broad spectrum of chemical and physical properties which can affect antibacterial efficacy. This manuscript describes the pulsed laser-ablation in liquids (PLAL) method to create nanoparticles. This approach allows for the fine tuning of nanoparticle size, composition, and stability using post-irradiation methods as well as the addition of surfactants or volume excluders. By controlling particle size and composition, a large range of physical and chemical properties of metal nanoparticles can be explored which may contribute to their antimicrobial efficacy thereby opening new avenues for antibacterial development.

The antimicrobial properties of metals such as copper and silver have been recognized for centuries. This protocol describes pulsed laser-ablation in liquids, a method of synthesizing metal nanoparticles that provides the ability to fine tune the properties of these nanoparticles to optimize their antimicrobial effects.

The emergence of multidrug-resistant bacteria is a global clinical concern leading some to speculate about our return to a "pre-antibiotics" era of ...

Synthesis of Monocyte-targeting Peptide Amphiphile Micelles for Imaging of Atherosclerosis

Atherosclerosis is a major contributor to cardiovascular disease, the leading cause of death worldwide, which claims 17.3 million lives annually. Atherosclerosis is also the leading cause of sudden death and myocardial infarction, instigated by unstable plaques that rupture and occlude the blood vessel without warning. Current imaging modalities cannot differentiate between stable and unstable plaques that rupture. Peptide amphiphiles micelles (PAMs) can overcome this drawback as they can be modified with a variety of targeting moieties that bind specifically to diseased tissue. Monocytes have been shown to be early markers of atherosclerosis, while large accumulation of monocytes is associated with plaques prone to rupture. Hence, nanoparticles that can target monocytes can be used to discriminate different stages of atherosclerosis. To that end, here, we describe a protocol for the preparation of monocyte-targeting PAMs (monocyte chemoattractant protein-1 (MCP-1) PAMs). MCP-1 PAMs are self-assembled through synthesis under mild conditions to form nanoparticles of 15 nm in diameter with near neutral surface charge. In vitro, PAMs were found to be biocompatible and had a high binding affinity for monocytes. The methods described herein show promise for a wide range of applications in atherosclerosis as well as other inflammatory diseases.

This paper presents a method involving the synthesis and characterization of monocyte-targeting peptide amphiphile micelles and the corresponding assays to test for biocompatibility and ability of the micelle to bind to monocytes.

Atherosclerosis is a major contributor to cardiovascular disease, the leading cause of death worldwide, which claims 17.3 million lives annually. ...

Synthesis of Multi-walled Carbon Nanotubes Modified with Silver Nanoparticles and Evaluation of Their Antibacterial Activities and Cytotoxic Properties

In this study, multi-walled carbon nanotubes (MWCNTs) were treated with an aqueous sulfuric acid solution to form an oxygen-based functional group. Silver MWCNTs were prepared by the reductive deposition of silver from an aqueous solution of AgNO3 on the oxidized MWCNTs. Given the unique color of the CNTs, it was not possible to apply them to the minimum inhibitory concentration or mitochondrial toxicity assays to evaluate the toxicity and antibacterial properties, since they would interfere with the assays. The inhibition zone and minimum bactericidal concentration for the Ag-MWCNTs were measured and Live/Dead and Trypan Blue assays were used to measure the toxicity and antibacterial properties without interfering with the color of the CNTs.

In this study, antimicrobial nanomaterials were synthesized by acidic oxidation of multiwalled carbon nanotubes and subsequent reductive deposition of silver nanoparticles. Antimicrobial activity and cytotoxicity tests were performed with the as-prepared nanomaterials.

In this study, multi-walled carbon nanotubes (MWCNTs) were treated with an aqueous sulfuric acid solution to form an oxygen-based functional group. Silver ...