Name: preparation of chitosan-based injectable hydrogels and its application in 3d cell culture
Uploaded: 2017-09-29T14:00:00
Description: Watch this Scientific Journal Video about Preparation of Chitosan-based Injectable Hydrogels and Its Application in 3D Cell Culture at JoVE.com

This research was supported by the National Science Foundation of China (21474057 and 21604076).

CAUTION: Please consult all relevant material safety data sheets (MSDS) before use. Please use appropriate safety practices when performing chemistry experiments, including the use of a fume hood and personal protective equipment (safety glasses, protective gloves, lab coat, etc.). The protocol requires standard cell handling techniques (sterilizing, cell recovery, cell passaging, cell freezing, cell staining, etc.).
1. Preparation of Hydrogels
<ol>
	<li>Synthesis o...

<ol>
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The hydrogel presented in this protocol (Figure 1) has two main components: the natural polymer glycol chitosan and a synthetic benzaldehyde terminated polymer gelator DF PEG, which are both biocompatible materials. Synthesis of DF PEG is presented using a one-step modification reaction. PEG of molecular weight 4,000 was chosen in this protocol in concerns of solubility, modification efficiency, as well as hydrogel stiffness. A series of hydrogels with different mechanical strengths were pre...

Hydrogels are crosslinked polymer materials with large amounts of water and soft mechanical properties, and they have been used in many bio-medical applications1,2. Hydrogels can offer a soft and wet environment, which is very similar to the physiological surroundings for cells in vivo. Therefore, hydrogels have become one of the most popular scaffolds for 3D cell culture3,4. Compared to 2D Petri dish cell culture, 3D cell culture has advanced quickly to offer an extracellular matrix (ECM) mimicked microenvironment for cells to contact and assemble for proliferation and differentiation purposes5. Additionally, hydrogels containing natural polymers could offer bio-compatible and promoting environments for cells to proliferate and differentiate3. Hydrogels derived from synthetic polymers are preferred for their simple and clear components, which exclude complex influences like animal-origin proteins or viruses. Among all the hydrogel candidates for 3D cell culture, hydrogels that are easily prepared and have a consistent property are always preferred. The facility to adjust the hydrogel&#39;s properties to fit different research requirements is important as well6.
Here we introduce a facile preparation of a glycol chitosan-based hydrogel using dynamic imine chemistry, which becomes a versatile hydrogel platform for 3D cell culture7. In this method, well-known bio-compatible glycol chitosan are used to establish frames of the hydrogel&#39;s networks. Its amino groups are reacted with a benzaldehyde terminated polyethylene glycol as the polymer gelator to form dynamic imine bonds as crosslinkages of hydrogels8. Dynamic imine bonds can form and decompose reversibly and responsively to surroundings, endowing the hydrogels with mechanically adjustable crosslinked networks9,10,11. Due to its high water contents, bio-compatible materials, and adjustable mechanical strengths, the hydrogel is successfully applied as a scaffold for L929 cells in 3D cell culture12,13. The protocol here details the procedures, including polymer gelator synthesis, hydrogel preparation, cell embedding, and 3D cell culturing.
The hydrogel also shows several other features due to its dynamic imine crosslinkages, including its multi-responsive to various bio-stimuli (acid/pH, vitamin B6 derivative pyridoxal, protein papain, etc.), indicating that the hydrogel could be induced to decompose under physiological conditions8. The hydrogel is also self-healable and injectable, which means the hydrogel could be administrated via a minimal invasive injection method and gain an advantage in drug and cell deliveries14,15. By adding functional additives or specific predesigned polymer gelators, the hydrogel is compatible to gaining specific properties like magnetic, temperature, pH responsive, etc.16,17, which could fulfill a wide range of research requirements. Those properties reveal the hydrogel&#39;s potential capacity to be an injectable multiple carriers for drugs and cells in both in vitro and in vivo bio-medical research and applications.

<table border="0" cellpadding="0" cellspacing="0" width="1151">
	<tbody>
		<tr height="20">
			<td height="20" style="height:20px;width:276px;">Glycol chitosan</td>
			<td style="width:360px;">Wako Pure Chemical Industries</td>
			<td style="width:131px;">39280-86-9</td>
			<td style="width:385px;">90% degree of deacetylation</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">4-Carboxybenzaldehyde</td>
			<td>Shanghai Aladdin&#160;Bio-Chem Technology Co.,LTD</td>
			<td>619-66-9</td>
			<td>99%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">N, N&#39;-dicyclohexylcarbodiimide</td>
			<td>Shanghai Aladdin&#160;Bio-Chem Technology Co.,LTD</td>
			<td>538-75-0</td>
			<td>99%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Calcium chloride anhydrous</td>
			<td>Shanghai Aladdin&#160;Bio-Chem Technology Co.,LTD</td>
			<td>10043-52-4</td>
			<td>96%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">4-dimethylamiopryidine</td>
			<td>Shanghai Aladdin&#160;Bio-Chem Technology Co.,LTD</td>
			<td>1122-58</td>
			<td>99%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Polyethyleneglycol</td>
			<td>Sino-pharm Chemical Reagent</td>
			<td>5254-43-7</td>
			<td>99%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Tetrahydrofuran</td>
			<td>Sino-pharm Chemical Reagent</td>
			<td>109-99-9</td>
			<td>99%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Toluene</td>
			<td>Sino-pharm Chemical Reagent</td>
			<td>108-88-3</td>
			<td>99%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Ethyl ether</td>
			<td>Sino-pharm Chemical Reagent</td>
			<td>60-29-7</td>
			<td>99%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Acetic acid</td>
			<td>Sino-pharm Chemical Reagent</td>
			<td>64-19-7</td>
			<td>99%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Anhydrous CaCl2</td>
			<td>Sino-pharm Chemical Reagent</td>
			<td>10043-52-4</td>
			<td>99%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Fluorescein diacetate</td>
			<td>Sigma</td>
			<td>596-09-8</td>
			<td>99%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Propidium iodide&#160;</td>
			<td>Sigma</td>
			<td>25535-16-4</td>
			<td>94%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">RPMI-1640 culture media</td>
			<td>Gibco</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Fetal bovine serum</td>
			<td>Gibco</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Trypsin-EDTA</td>
			<td>Gibco</td>
			<td></td>
			<td>0.25%</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">PBS</td>
			<td>Solarbio</td>
			<td></td>
			<td>0.01 M</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Penicillin streptomycin solution</td>
			<td>Hyclone</td>
			<td></td>
			<td>10,000 U/mL</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Rheometer</td>
			<td>TA Instrument</td>
			<td></td>
			<td>AR-G2</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Confocal microscope</td>
			<td>Zeiss</td>
			<td></td>
			<td>710-3channel</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">L929 Cells</td>
			<td>ATCC</td>
			<td></td>
			<td>NCTC clone 929; L cell, L929, derivative of Strain L</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Evaporator</td>
			<td>EYELA</td>
			<td></td>
			<td>N-1100</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">48 guage needle</td>
			<td>ShanghaiZhiyu Medical Material Co., LTD</td>
			<td></td>
			<td>48-guage</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Microscope</td>
			<td>Leica</td>
			<td></td>
			<td>DM3000 B</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Microscope software</td>
			<td>Imaris</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Heat gun</td>
			<td>Confu</td>
			<td></td>
			<td>KF-5843&#160;</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Petri dish</td>
			<td>NEST</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

preparation of chitosan-based injectable hydrogels and its application in 3d cell culture

The protocol presents a facile, efficient, and versatile method to prepare chitosan-based hydrogels using dynamic imine chemistry. The hydrogel is prepared by mixing solutions of glycol chitosan with a synthesized benzaldehyde terminated polymer gelator, and hydrogels are efficiently obtained in several minutes at room temperature. By varying ratios between glycol chitosan, polymer gelator, and water contents, versatile hydrogels with different gelation times and stiffness are obtained. When damaged, the hydrogel can recover its appearances and modulus, due to the reversibility of the dynamic imine bonds as crosslinkages. This self-healable property enables the hydrogel to be injectable since it can be self-healed from squeezed pieces to an integral bulk hydrogel after the injection process. The hydrogel is also multi-responsive to many bio-active stimuli due to different equilibration statuses of the dynamic imine bonds. This hydrogel was confirmed as bio-compatible, and L929 mouse fibroblast cells were embedded following standard procedures and the cell proliferation was easily assessed by a 3D cell cultivation process. The hydrogel can offer an adjustable platform for different research where a physiological mimic of a 3D environment for cells is profited. Along with its multi-responsive, self-healable, and injectable properties, the hydrogels can potentially be applied as multiple carriers for drugs and cells in future bio-medical applications.

A schematic presentation of this protocol on hydrogel preparation and its use as 3D cell culture is offered in Figure 1. Information of the hydrogel&#39;s contents and ratios prepared with different mechanical strengths is summarized in Table 1. The hydrogel&#39;s self-healable and rheology property presents the hydrogel&#39;s stiffness by storage modulus versus frequency test in Figure 2. The cell confocal images and cell numbers with days of c...

Watch this Scientific Journal Video about Preparation of Chitosan-based Injectable Hydrogels and Its Application in 3D Cell Culture at JoVE.com

Preparation of Chitosan-based Injectable Hydrogels and Its Application in 3D Cell Culture

Here we describe a facile preparation of chitosan-based injectable hydrogels using dynamic imine chemistry. Methods to adjust the hydrogel&#8217;s mechanical strength and its application in 3D cell culture are presented.

The protocol presents a facile, efficient, and versatile method to prepare chitosan-based hydrogels using dynamic imine chemistry. The hydrogel is ...

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