Name: the synthesis of rgd-functionalized hydrogels as a tool for therapeutic applications
Uploaded: 2016-10-07T14:00:00
Description: Watch this Scientific Journal Video about The Synthesis of RGD-functionalized Hydrogels as a Tool for Therapeutic Applications at JoVE.com

Autoren möchte Prof. Maurizio Masi für eine fruchtbare Diskussion und Fräulein Chiara Allegretti für Lektur danken. Autoren Forschung wird von Bando Giovani Ricercatori 2010 (Ministero della Salute GR-2010- 2312573) unterstützt.

Anmerkung: Die verwendeten Chemikalien sind wie empfangen. Linear RGD gekauft wird , aber es kann durch Standard - Fmoc - Festphasen - Peptidsynthese 16,19 hergestellt werden. Lösungsmittel sind von analytischer Qualität. Die Dialyse erfordert die Verwendung von Membran mit einem M w cut-off gleich 3.500 Da. Die synthetisierten Verbindungen werden durch 1 H - NMR - Spektren wurden auf einem 400 MHz - Spektrometer unter Verwendung von Chloroform (CDCl 3) oder Deuteriumoxid (D...

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The PAA post-polymerization modification with alkyne moieties and the RGD functionalization with the azide group guarantee the formation of a stable bond between the polymer and the peptide. Indeed, triazole serves as a rigid linking unit among the carbon atoms, attached to the 1,4 positions of the 1,2,3-triazole ring and it cannot be cleaved hydrolytically or otherwise. In addition, triazole is extremely difficult to oxidize and reduce, unlike other cyclic structures such as benzenoids and related aromatic heterocycles<...

Hydrogele sind dreidimensionale Netzwerke durch hydrophile vernetzte Polymere gebildet werden, die natürlich oder synthetisch sind, und die durch eine ausgeprägte dreidimensionale Struktur aus. Diese Geräte sind zunehmend attraktiv in den biomedizinischen Bereichen Medikamentenabgabe, Tissue Engineering, Genträger und intelligente Sensoren 1,2. Tatsächlich ihres hohen Wassergehaltes sowie ihre rheologischen und mechanischen Eigenschaften machen sie geeignete Kandidaten Weichgewebe Mikroumgebungen zu imitieren und sie wirksame Werkzeuge für wasserlösliche Zytokin oder Wachstumsfaktor-Lieferung. Einer der vielversprechendsten ist die Verwendung als injizierbare Biomaterial Zellen und bioaktiven Verbindungen trägt. Hydrogele können das Überleben von Zellen und Kontrollstammzell Schicksal durch Halten und präzise Abgabe Stammzellregulationssignale in einer physiologisch relevanten Art und Weise verbessern, wie 3,4 in in vitro und in in vivo Experimenten beobachtet. Der führende Vorteil hierbei ist die Möglichkeit,injizierten Zellen innerhalb der Zone der Impfung (in situ), Minimierung der Menge an Zellen zu erhalten, die das Gebiet und Extravasate in den Kreis Strom verlässt, über den ganzen Körper der Migration und dem angestrebten Ziel 5 zu verlieren. Die Stabilität der dreidimensionalen Netzwerke Hydrogels ist aufgrund seiner Vernetzungsstellen, gebildet durch kovalente Bindungen oder Kohäsionskräfte zwischen den Polymerketten 6. In diesem Rahmen angewendet orthogonal selektive Chemie an Polymerketten ist ein vielseitiges Werkzeug in der Lage 7 Hydrogel Leistungen zu verbessern. Tatsächlich könnte die Modifikation von Polymeren mit geeigneten chemischen Gruppen helfen, geeignete chemische, physikalische und mechanische Eigenschaften bereitzustellen Lebensfähigkeit der Zellen und deren Verwendung in der Gewebebildung zu verbessern. In gleicher Weise zu den Techniken Zellen oder Wachstumsfaktoren innerhalb der Gelmatrix, die Verwendung des RGD-Peptid ermöglicht Verbesserungen in der Zelladhäsion und das Überleben zu laden. RGD ist ein Tripeptid zusammengesetztvon Arginin, Glycin und Asparaginsäure, die bei weitem das wirksamste und oft eingesetzt Tripeptid aufgrund seiner Fähigkeit , mehr als eine Zelladhäsion - Rezeptor und seine biologische Wirkung auf die Zellverankerung, Verhalten und Überleben 8,9 zu adressieren ist. In dieser Arbeit wird die Synthese von RGD-funktionalisierten Hydrogele mit dem Ziel der Netzwerke durch ausreichende biochemische Eigenschaften für eine gastliche Zelle Mikro gekennzeichnet Gestaltung studiert. Die Verwendung von Mikrowellenstrahlung in Hydrogel - Synthese bietet ein einfaches Verfahren , um Nebenreaktionen zu minimieren und höhere Reaktionsgeschwindigkeiten und Ausbeuten in kürzerer Zeit im Vergleich zu den herkömmlichen thermischen Verfahren 10 erhalten. Dieses Verfahren erfordert keine Reinigungsstufen und Ausbeuten sterile Hydrogele aufgrund der Wechselwirkungen der Polymere und der Abwesenheit eines organischen Lösungsmittels in dem Reaktionssystem 11. Daher gewährleistet es einen hohen Prozentsatz von RGD gebunden an das polymere Netzwerk, da kein modkationen werden den Polymer chemischen Gruppen erforderlich Gelbildung beteiligt. Carboxygruppen, von PAA und Carbomer, und Hydroxylgruppen von PEG und Agarose, führen zu dem Hydrogel dreidimensionale Struktur durch eine Polykondensationsreaktion. Die genannten Polymere werden für die Synthese von Hydrogelen in die Rückenmarksverletzung Reparaturbehandlungen 12 verwendet. Diese Geräte, wie in den vorangegangenen berichtet arbeitet 13,14, zeigen eine hohe Biokompatibilität sowie mechanischen und physikalisch - chemische Eigenschaften, die denen von vielen lebenden Geweben und in thixotropen Natur ähneln. Außerdem bleiben sie in situ lokalisiert in der Zone der Injektion. In dieser Arbeit PAA Carboxylgruppen mit einem Alkin - Einheit (1) modifiziert und eine RGD-Azid - Verbindung synthetisiert wird , die Reaktivität des Tripeptids Endgruppe NH 2 mit einer vorbereiteten chemische Verbindung mit der Struktur zu nutzen (CH 2) n - N 3 (&lt;strong&gt; Abbildung 2). Anschließend reagiert das modifizierte PAA mit dem RGD-Azid - Derivat durch CuAAC Klick - Reaktion 15-17 (Abbildung 3). Die Verwendung eines Kupfer (I) -Katalysator führt zu wesentlichen Verbesserungen in sowohl die Reaktionsgeschwindigkeit und die Regioselektivität. Die CuAAC Reaktion wird in der organischen Synthese und in der Polymerwissenschaft weit verbreitet. Es verbindet einen hohen Wirkungsgrad und eine hohe Toleranz gegenüber den funktionellen Gruppen, und es ist unabhängig von der Verwendung von organischen Lösungsmitteln. Eine hohe Selektivität, eine schnelle Reaktionszeit und eine einfache Reinigungsverfahren ermöglichen die Gewinnung von Sternpolymeren, Blockcopolymere oder Ketten gewünschten Einheiten 18 Pfropfen. Dieser Klick-Strategie ermöglicht es, Polymere nach der Polymerisation zu modifizieren, um die physikalisch-chemischen Eigenschaften nach der endgültigen biochemischen Anwendung anpassen. Die CuAAC experimentellen Bedingungen sind leicht reproduzierbar (die Reaktion ist unempfindlich gegen Wasser, während Kupfer Oxidation minimal auftreten kann), und die Art dergebildet Triazol sorgt für Stabilität des Produkts. Die Verwendung von Kupfermetall kann ein kritischer Punkt, aufgrund seiner potentiellen toxischen Wirkung gegenüber Zellen und in der biologischen Mikroumgebung in Betracht gezogen werden, aber der Dialyse wird als Reinigungsverfahren verwendet, um die vollständige Entfernung von katalytischen Rückständen ermöglichen. Schließlich PAA modifizierte RGD in Hydrogel - Synthese (4) und die physikalisch - chemischen Eigenschaften der resultierenden Netzwerken verwendet wird untersucht, um die potentielle Funktionalität dieser Systeme als Zellen oder Drogen Träger zu überprüfen. <img alt="Abbildung 1" src="/files/ftp_upload/54445/54445fig1.jpg" /> Abbildung 1: PAA modifizierte Alkin Synthese ein Schema PAA Funktionalisierung mit Alkin - Gruppe;. &quot;n&quot; gibt die Monomere mit Carboxylgruppe mit Propargylamin reagieren. <a href="http://ecsource.jove.com/files/ftp_upload/54445/54445fig1large.jpg" target="_blank">Bitte klicken Sie hier um zu sehen</a>eine größere Version dieser Figur. <img alt="Figur 2" src="/files/ftp_upload/54445/54445fig2.jpg" /> Abbildung 2:.. RGD-Azid - Synthese Die Synthese von RGD-Azid - Derivat <a href="http://ecsource.jove.com/files/ftp_upload/54445/54445fig2large.jpg" target="_blank">Bitte hier klicken</a> , um <a href="http://ecsource.jove.com/files/ftp_upload/54445/54445fig2large.jpg" target="_blank">eine größere Version dieser Figur zu sehen.</a> <img alt="Figur 3" src="/files/ftp_upload/54445/54445fig3.jpg" /> Abbildung 3: Klicken Sie auf Reaktionsschema der Klick - Reaktion zwischen RGD-Azid - Derivat und Alkin-PAA.. <a href="http://ecsource.jove.com/files/ftp_upload/54445/54445fig3large.jpg" target="_blank">Bitte klicken Sie hier</a> , um <a href="http://ecsource.jove.com/files/ftp_upload/54445/54445fig3large.jpg" target="_blank">eine größere Version dieser Figur zu sehen.</a> <img alt="Abbildung 4" src="/files/ftp_upload/54445/54445fig4.jpg" /> Abbildung 4: Hydrogele synthesis. RGD funktionalisierten Hydrogel - Syntheseverfahren. <a href="http://ecsource.jove.com/files/ftp_upload/54445/54445fig4large.jpg" target="_blank">Bitte klicken Sie hier</a> , um <a href="http://ecsource.jove.com/files/ftp_upload/54445/54445fig4large.jpg" target="_blank">eine größere Version dieser Figur zu sehen.</a>

<table border="0" cellpadding="0" cellspacing="0" width="521">
	<tbody>
		<tr height="67">
			<td height="67" style="height:67px;width:183px;">Poly(acrylic acid) solution average Mw ~ 100,000, 35 wt % in H2O</td>
			<td style="width:108px;">Sigma Aldrich</td>
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the synthesis of rgd-functionalized hydrogels as a tool for therapeutic applications

The use of polymers as biomaterials has provided significant advantages in therapeutic applications. In particular, the possibility to modify and functionalize polymer chains with compounds that are able to improve biocompatibility, mechanical properties, or cell viability allows the design of novel materials to meet new challenges in the biomedical field. With the polymer functionalization strategies, click chemistry is a powerful tool to improve cell-compatibility and drug delivery properties of polymeric devices. Similarly, the fundamental need of biomedicine to use sterile tools to avoid potential adverse-side effects, such as toxicity or contamination of the biological environment, gives rise to increasing interest in the microwave-assisted strategy.
The combination of click chemistry and the microwave-assisted method is suitable to produce biocompatible hydrogels with desired functionalities and improved performances in biomedical applications. This work aims to synthesize RGD-functionalized hydrogels. RGD (arginylglycylaspartic acid) is a tripeptide that can mimic cell adhesion proteins and bind to cell-surface receptors, creating a hospitable microenvironment for cells within the 3D polymeric network of the hydrogels. RGD functionalization occurs through Huisgen 1,3-dipolar cycloaddition. Some PAA carboxyl groups are modified with an alkyne moiety, whereas RGD is functionalized with azido acid as the terminal residue of the peptide sequence. Finally, both products are used in a copper catalyzed click reaction to permanently link the peptide to PAA. This modified polymer is used with carbomer, agarose and polyethylene glycol (PEG) to synthesize a hydrogel matrix. The 3D structure is formed due to an esterification reaction involving carboxyl groups from PAA and carbomer and hydroxyl groups from agarose and PEG through microwave-assisted polycondensation. The efficiency of the gelation mechanism ensures a high degree of RGD functionalization. In addition, the procedure to load therapeutic compounds or biological tools within this functionalized network is very simple and reproducible.

Die PAA Alkin - Derivat effizient aus Polyacrylsäure und Propargylamin synthetisiert, wie in Abbildung 1 gezeigt , wobei n die Monomere , deren Carboxyl - Gruppen reagieren mit dem Amin - Etiketten. Die Identität des Produkts wird durch 1 H-NMR - Spektroskopie bestätigt. Abbildung 5 Die 1 H-NMR - Spektrum von PAA zeigt mit Dreifachbindung modifiziert. <img alt="Abbildung 5" src="/files/ftp_upl...

Watch this Scientific Journal Video about The Synthesis of RGD-functionalized Hydrogels as a Tool for Therapeutic Applications at JoVE.com

The Synthesis of RGD-functionalized Hydrogels as a Tool for Therapeutic Applications

We present a protocol for the synthesis of RGD-functionalized hydrogels as devices for cell and drug delivery. The procedure involves copper catalyzed alkyne-azide cycloaddition (CuAAC) between alkyne-modified polyacrylic acid (PAA) and a RGD-azide derivative. The hydrogels are formed using microwave-assisted polycondensation and their physicochemical properties are investigated.

Die Synthese von RGD-funktionalisierten Hydrogele als Werkzeug für therapeutische Anwendungen

The use of polymers as biomaterials has provided significant advantages in therapeutic applications. In particular, the possibility to modify and ...

The overall goal of this methodology is to synthesize hydrogels for tissue engineering applications very easily. This method can help answer key questions in the tissue engineering field, such as the possibility to maintain high cell viability in three dimensional cell culture systems. The main advantage of this technique is that is using quick reaction, we can easily modify hydrogel systems to improve their ability to maintain cell viable.The implications of this technique extend toward the therapy of spinal cord injury because the cells loaded within the scaffold can rebuild the damaged tissue. For this method can provide significant insight into cell therapies as regenerative medicine and their implication in many methodologies. It can also be applied in several other systems like bone, heart, and cartilage.To synthesize the RGD-azide derivative, dissolve 50 milligrams of RGD in one milliliter of one molar sodium hydroxide. Then dissolve 24 milligrams of 4-azidobutanoyl chloride in two milliliters of tetrahydrofuran. Add all of the RGD solution into the 4-azidobutanoyl chloride solution at zero degrees Celsius dropwise.Return to room temperature and stir overnight. Add one milliliter of one molar HCL. Remove the solvent under reduced pressure using a rotary evaporator.Characterize the obtained product by proton nuclear magnetic resonance spectroscopy, dissolving the sample in deuterium oxide or D2O. To perform the PAA alkine modification, dissolve 200 milligrams of 35%in weight PAA solution in 15 milliliters of distilled water. Add 15.4 milligrams of propargylamine hydrochloride.Then dissolve 42.8 milligrams of HOBt in 14 milliliters of a one to one ratio of acetonytryle distilled water solution by heating to 50 degrees Celsius. Add all of the HOBt solution to the PAA solution at room temperature. Next, add 53.6 milligrams of EDC to the reaction mixture.Use one molar HCL to adjust the PH to 5.5 and stir the reaction system overnight at room temperature. Next, dissolve 11.2 grams of sodium chloride in two liters of distilled water. And then add 200 microliters of 37%weight by weight HCL.Dialyze the solution using a membrane with a molecular weight cutoff of 3.5 kilodaltons. Perform dialysis for three days. Change the dialysis solution daily with two liters of freshly prepared distilled water containing 200 microliters of 37%weight by weight HCL.Store the final solution at minus 80 degrees Celsius. Characterize the functionalized polymer by proton nuclear magnetic resonance spectroscopy, dissolving the sample in D2O. To synthesize the PAA-RGD polymer, dissolve 78 milligrams of PAA modified alkine in 10 milliliters of distilled water.Then dissolve 25 milligrams of the RGD-azide derivative in five milliliters of tetrahydrafuran. Add all of the RGD solution to the polymeric solution. Next, add 2.2 milligrams of copper iodide.And 2.2 milligrams of sodium ascorbate. Reflux the resulting mixture overnight at 60 degrees Celsius with stirring. Cool the mixture to 25 degrees Celsius.To dialyze the solution, dissolve 11.2 grams of sodium chloride in two liters of distilled water and add 200 microliters of 37 percent weight by weight HCL. Perform dialysis for three days. Change the dialysis solution daily with two liters of freshly prepared distilled water containing 200 microliters of 37%weight by weight HCL.Then place the final solution at minus 80 degrees Celsius. Characterize and store the resulting PAA-RGD polymer as done for its constituents. Blend 40 milligrams of carbomer and 10 milligrams of the functionalized PAA in nine milliters of phosphate-buffered saline at room temperature until complete dissolution.Add 400 milligrams of PEG to the solution and keep stirring for 45 minutes. Stop the stirring and allow the system to settle for 30 minutes. Then use one molar sodium hydroxide to adjust the PH to 7.4.To five milliliters of the obtained mixture, add 25 milligrams of agarose powder. Irradiate the system with microwave radiation at 500 watts for 30 seconds to one minute until boiling. And electromagnetically heat up the solution to 80 degrees Celsius.Leave the mixture exposed to room temperature until its temperature decreases to 50 degrees Celsius. Then add five milliliters of PBS to obtain a solution at a one to one volumetric ratio. Prepare a 12-multiwell plate containing steel cylinders with a diameter of 1.1 centimeters.Take 500 microliters aliquots from the solution and place them into each steel cylinder. Leave the plate at rest for 45 minutes until complete gelification of the system. Remove the cylinders using stainless steel forceps to obtain the hydrogels.See the text protocol for characterizing the physicochemical properties of the RGD-functionalized hydrogels. Carbomer 974P, PAA-RGD, and PEG, together with agarose, take part in a statistical random polycondensation after microwave irradiation. Hydroxyl groups contained in PEG and agarose react with carboxyl groups present in Carbomer 947P and PAA-RGD to form ACPEG-RGD hydrogels.Considering rheological properties, the storage modulus was found to be approximately one order of magnitude higher than the loss modulus, indicating an elastic rather than viscous material. Moreover, it is clearly visible that hydrogel behavior is dominated at low strain values by the elastic modulus. Scanning electron microscopy shows the morphology of an RGD functionalized hydrogel sample and a hydrogel without functionalization.Both hydrogels revealed that they possess a highly entangled structure of interconnected pores, with some bigger pores containing small pores and some fibular networks on the pore walls. The similar properties indicate that the presence of RGD does not alter the polymer network. After this development, this technique paved the way for research in the field of tissue engineering to explore the stability of these cell culture systems in several other diseases.After watching this video, you should have a good understanding of how to functionalize hydrogels. Improving their ability to maintain viable stem cells.

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