This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (MEST) [NRF-2015R1D1A1A01060397] and Bio &#38; Medical Technology Development Program of the NRF funded by the Ministry of Science, ICT &#38; Future Planning [NRF-2017M3A9C6029563].

This study was approved by the Institutional Review Board at Korea University Anam Hospital (IRB No. ED170495). All procedures were carried out in accordance with the Helsinki Declaration and its later amendments.
1. Preparation of Aluminum (Al) Substrate by Electropolishing
Caution: Electropolishing solution is corrosive and toxic. Wear personal protective equipment including nitrile gloves, goggles and lab coat. Perform this step in a fume hood....

<ol>
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Fabrication of an AAO often suffers from defects such as cracks, irregular shapes of pores, and burning. The main reason for these defects is called an electrolytic breakdown, which is strongly affected by the nature of the metal substrates being anodized and the resistivity of the electrolyte21. Since the resistivity of the electrolyte varies depending on its temperature, eliminating heat continuously from electrodes is the critical point to maintain the locational temperature of the electrolyte ...

Recently, the response of cells by the physical stimulation of surface topography has been spotlighted in the field of cell engineering1,2,3,4. Therefore, more attention has been focused on three-dimensional nanostructures at the cell attachment surface5. It has been reported that the integrin, which is the surface recognition device of the cell, transmits the physical stimulus driven by the micro-nano structures of ECM through mechano-transduction6. This mechanical stimulation regulates cell behavior through contact guidance7 and induces cytoskeletal reorganization to change shape, in addition to focal adhesions and stiffness of cells8.
Human endothelial progenitor cells (hEPCs) in the body closely interact with the microenvironment of the surrounding ECM9. This indicates that the physical state of the ECM acts as an important parameter for specific cell-matrix adhesion complex formation as much as shear stress derived from blood flow10. It is reported that surface nanotopography enhances the in vitro formation of extensive capillary tube networks of hEPCs11 and that an ECM/bio soluble factor combined system enables hEPCs to recognize dysfunctional substrates and promotes wound healing12,13. Nonetheless, the relationship between ECM and hEPCs is not clearly understood.
Although many researchers tried to clarify the relationship between cell responses and physical cues from different substrates14,15,16, these studies used only the fixed size of a nanostructure or nanopatterns with irregular arrangements that have a limitation to elucidate the relationship between the size of the nanostructure and cell behavior. The problem here is a lack of suitable tools for screening cellular responses that can replace existing tedious and iterative approaches to find the optimum size of the nanostructure. Therefore, a straightforward technique is required for screening cell reactions on physical stimulations without repetition.
Here, we describe a method used in our previous reports17,18,19 to produce a gradient nanopattern in which the diameter of the arranged nanopillars gradually increases. In addition, we also described how to cultivate and analyze the behavior of hECFCs on gradient nanopattern plates to determine the effect of physical stimuli on the cells. A mild anodization, gradual etching, and anti-sticking layer coating method were used to fabricate gradient AAO mold. By adopting a thermal imprinting lithography technique, identical polystyrene gradient nanopatterns were produced in a cost-effective and facile way. Using gradient nanopatterns, it is feasible to determine which size of nanostructure has a great effect on cell behavior in one set of experiment. We expect that this gradient nanopattern will be helpful in understanding the interaction mechanisms between blood-derived hECFC or other cells and various sizes of nanostructures.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Perchloric acid 60%</td>
			<td>Daejung Chemicals &#38; Metals</td>
			<td>6512-4100</td>
			<td></td>
		</tr>
		<tr>
			<td>Ethyl alcohol, absolute 99.9%</td>
			<td>Daejung Chemicals &#38; Metals</td>
			<td>4118-4100</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphoric acid 85%</td>
			<td>Daejung Chemicals &#38; Metals</td>
			<td>6532-4400</td>
			<td></td>
		</tr>
		<tr>
			<td>Methyl alcohol 99.5%</td>
			<td>Daejung Chemicals &#38; Metals</td>
			<td>5558-4400</td>
			<td></td>
		</tr>
		<tr>
			<td>Chromium(VI) oxide</td>
			<td>Daejung Chemicals &#38; Metals</td>
			<td>2558-4400</td>
			<td></td>
		</tr>
		<tr>
			<td>Sulfuric acid 95%</td>
			<td>Daejung Chemicals &#38; Metals</td>
			<td>7781-4100</td>
			<td></td>
		</tr>
		<tr>
			<td>Hydrogen peroxide 30%</td>
			<td>Daejung Chemicals &#38; Metals</td>
			<td>4104-4400</td>
			<td></td>
		</tr>
		<tr>
			<td>n-hexane 95%</td>
			<td>Daejung Chemicals &#38; Metals</td>
			<td>4081-4400</td>
			<td></td>
		</tr>
		<tr>
			<td>Toluene 99.5%</td>
			<td>Daejung Chemicals &#38; Metals</td>
			<td>8541-4400</td>
			<td></td>
		</tr>
		<tr>
			<td>(heptadecafluoro-1,1,2,2,-tetrahydrodecyl)dimethylchlorosilane</td>
			<td>Gelest</td>
			<td>SIH5840.4</td>
			<td>Moisture sensitive</td>
		</tr>
		<tr>
			<td>Methoxynonafluorobutane 99%</td>
			<td>Sigma aldrich</td>
			<td>464309</td>
			<td></td>
		</tr>
		<tr>
			<td>Collagen solution</td>
			<td>Stemcell</td>
			<td>#4902</td>
			<td></td>
		</tr>
		<tr>
			<td>Gelatin</td>
			<td>Sigma aldrich</td>
			<td>G1890</td>
			<td>Protein coating solution</td>
		</tr>
		<tr>
			<td>Ficoll-Paque</td>
			<td>GE Heathcare</td>
			<td>17-1440-03</td>
			<td>Hydrophilic polysaccharide solution</td>
		</tr>
		<tr>
			<td>EGM-2MV</td>
			<td>Lonza</td>
			<td>CC-3202</td>
			<td>Endothelial cell expansion medium</td>
		</tr>
		<tr>
			<td>Penicillin-Streptomycin</td>
			<td>Gibco</td>
			<td>15140-122</td>
			<td></td>
		</tr>
		<tr>
			<td>Phosphate buffered saline</td>
			<td>Gibco</td>
			<td>10010031</td>
			<td></td>
		</tr>
		<tr>
			<td>Fetal bovine serum</td>
			<td>Gibco</td>
			<td>12483-020</td>
			<td></td>
		</tr>
		<tr>
			<td>Paraformaldehyde</td>
			<td>Sigma aldrich</td>
			<td>P6148</td>
			<td></td>
		</tr>
		<tr>
			<td>Glutaraldehyde</td>
			<td>Sigma aldrich</td>
			<td>G5882-100ML</td>
			<td></td>
		</tr>
		<tr>
			<td>Osmium tetroxide</td>
			<td>Sigma aldrich</td>
			<td>201030-1G</td>
			<td></td>
		</tr>
		<tr>
			<td>Hexamethyldisilazane</td>
			<td>Sigma aldrich</td>
			<td>440191</td>
			<td></td>
		</tr>
		<tr>
			<td>Triton X-100</td>
			<td>Sigma aldrich</td>
			<td>X100-100ML</td>
			<td>Octylphenol ethoxylate&#160;</td>
		</tr>
		<tr>
			<td>Goat serum</td>
			<td>Gibco</td>
			<td>26050-088</td>
			<td></td>
		</tr>
		<tr>
			<td>anti-human vinculin primary antibody&#160;</td>
			<td>Sigma aldrich</td>
			<td>V9131</td>
			<td></td>
		</tr>
		<tr>
			<td>F-actin probe</td>
			<td>Molecular Probes</td>
			<td>A12379</td>
			<td>Fluorescence-conjugated phalloidin</td>
		</tr>
		<tr>
			<td>Alexa Fluor 488-conjugated anti-mouse&#160;IgG antibody</td>
			<td>Molecular Probes</td>
			<td>A11001</td>
			<td>Fluorescence-conjugated secondary antibody&#160;</td>
		</tr>
		<tr>
			<td>4&#39;,6-diamidino-2-phenylindole&#160;</td>
			<td>Sigma aldrich</td>
			<td>D9542</td>
			<td></td>
		</tr>
		<tr>
			<td>Mounting medium</td>
			<td>DAKO</td>
			<td>S3023</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-human vWF primary antibody&#160;</td>
			<td>DAKO</td>
			<td>A0082</td>
			<td></td>
		</tr>
		<tr>
			<td>Anti-human&#160;CD144 primary antibody&#160;</td>
			<td>BD Biosciences</td>
			<td>#555661</td>
			<td></td>
		</tr>
		<tr>
			<td>Eponate 12&#8482; Embedding Kit, with BDMA</td>
			<td>Ted Pella</td>
			<td>18012</td>
			<td>Epoxy resin</td>
		</tr>
		<tr>
			<td>Uranyl Acetate, 25g</td>
			<td>Ted Pella</td>
			<td>19481</td>
			<td></td>
		</tr>
		<tr>
			<td>Lead Citrate, Trihydrate, 10g</td>
			<td>Ted Pella</td>
			<td>19312</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultra pure aluminum plate</td>
			<td>Goodfellow</td>
			<td>26050-088</td>
			<td></td>
		</tr>
		<tr>
			<td>Polystyrene sheet</td>
			<td>Goodfellow</td>
			<td>ST313120</td>
			<td></td>
		</tr>
		<tr>
			<td>8.0&#34; silicon wafer</td>
			<td>Siltron</td>
			<td>29-01024-03</td>
			<td>Single side polished, 725 &#181;m thick</td>
		</tr>
		<tr>
			<td>Vacuum desiccator, 4.4 L</td>
			<td>Kartell</td>
			<td>KA.230</td>
			<td></td>
		</tr>
		<tr>
			<td>Vacuum pump</td>
			<td>Vacuumer</td>
			<td>V3.VOP100</td>
			<td></td>
		</tr>
		<tr>
			<td>Power supply</td>
			<td>Unicorntech</td>
			<td>UDP-3003</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnetic stirrer</td>
			<td>Daihan scientific</td>
			<td>SL.SMS03022</td>
			<td></td>
		</tr>
		<tr>
			<td>Overhead stirrer</td>
			<td>Daihan scientific</td>
			<td>HT120DX</td>
			<td></td>
		</tr>
		<tr>
			<td>Circulator</td>
			<td>Daihan scientific</td>
			<td>WCR-P12</td>
			<td></td>
		</tr>
		<tr>
			<td>Linear moving stage</td>
			<td>Zaber</td>
			<td>A-LSQ300A-E01-KT07</td>
			<td></td>
		</tr>
		<tr>
			<td>Angle bracket, 90 degrees</td>
			<td>Zaber</td>
			<td>AB90M</td>
			<td>Accessory of the linear moving stage</td>
		</tr>
		<tr>
			<td>PMP forcep, 145 mm</td>
			<td>Vitlab</td>
			<td>67995</td>
			<td>Nonmetallic tweezer</td>
		</tr>
		<tr>
			<td>PTFE beaker, 250 mL</td>
			<td>Cowie</td>
			<td>CW007.25</td>
			<td></td>
		</tr>
		<tr>
			<td>Ultrasonic cleaner</td>
			<td>Branson</td>
			<td>B2510MTH</td>
			<td></td>
		</tr>
		<tr>
			<td>PCB cutter</td>
			<td>Hozan Tool Industrial</td>
			<td>K-110</td>
			<td></td>
		</tr>
		<tr>
			<td>Nanoimprint device</td>
			<td>Nanonex</td>
			<td>NX-2000</td>
			<td></td>
		</tr>
		<tr>
			<td>Oxygen plasma generator</td>
			<td>Femto Science</td>
			<td>CUTE</td>
			<td></td>
		</tr>
		<tr>
			<td>Low temperature sterilizer</td>
			<td>Lowtem</td>
			<td>Crystal 50</td>
			<td></td>
		</tr>
		<tr>
			<td>CO2 Incubator</td>
			<td>Panasonic</td>
			<td>MCO-18AC</td>
			<td></td>
		</tr>
		<tr>
			<td>Confoal laser scanning microscope</td>
			<td>Carl Zeiss</td>
			<td>LSM700</td>
			<td></td>
		</tr>
		<tr>
			<td>Scanning electron microscope</td>
			<td>JEOL</td>
			<td>JSM6701</td>
			<td></td>
		</tr>
		<tr>
			<td>Transmission electron microscope</td>
			<td>Hitachi</td>
			<td>H-7500</td>
			<td></td>
		</tr>
	</tbody>
</table>

fabrication of gradient nanopattern by thermal nanoimprinting technique and screening of the response of human endothelial colony-forming cells

Nanotopography can be found in various extracellular matrices (ECMs) around the body and is known to have important regulatory actions upon cellular reactions. However, it is difficult to determine the relation between the size of a nanostructure and the responses of cells owing to the lack of proper screening tools. Here, we show the development of reproducible and cost-effective gradient nanopattern plates for the manipulation of cellular responses. Using anodic aluminum oxide (AAO) as a master mold, gradient nanopattern plates with nanopillars of increasing diameter ranges [120-200&#8239;nm (GP 120/200), 200-280&#8239;nm (GP 200/280), and 280-360&#8239;nm (GP 280/360)] were fabricated by a thermal imprinting technique. These gradient nanopattern plates were designed to mimic the various sizes of nanotopography in the ECM and were used to screen the responses of human endothelial colony-forming cells (hECFCs). In this protocol, we describe the step-by-step procedure of fabricating gradient nanopattern plates for cell engineering, techniques of cultivating hECFCs from human peripheral blood, and culturing hECFCs on nanopattern plates.

Figure 1 shows SEM images of the fabricated gradient AAO molds according to their type and position. Figure 2 shows SEM images of gradient nanopattern plates with regular-rounded nanopillars, and Figure 3 is quantification data of the nanopillar diameter. Table 1 lists the characteristics of the fabricated nanopillars.
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Watch this Scientific Journal Video about Fabrication of Gradient Nanopattern by Thermal Nanoimprinting Technique and Screening of the Response of Human Endothelial Colony-forming Cells at JoVE.com

Fabrication of Gradient Nanopattern by Thermal Nanoimprinting Technique and Screening of the Response of Human Endothelial Colony-forming Cells

Here, we present a protocol for the fabrication of gradient nanopattern plates via thermal nanoimprinting and the method of screening responses of human endothelial progenitor cells to the nanostructures. By using the described technology, it is possible to produce a scaffold that can manipulate cell behavior by physical stimuli.

Nanotopography can be found in various extracellular matrices (ECMs) around the body and is known to have important regulatory actions upon cellular ...

The main advantage of this technique is that it can produce gradient patterns with high reproducibility and allowed the screening of cell response to parasites observational structures. The response observes to physical stimulation is not yet fully discovered. We believe that our method will be an essential tool to uncover these unknown mechanisms.To begin, connect a double jacket beaker containing the electropolishing solution to a circulator and set the temperature at seven degrees Celsius. Leave the solution under stirring for at least 30 minutes until the temperature drops to seven degrees Celsius. Immerse the ultra-pure aluminum plate and carbon counter electrode into the electropolishing solution using crocodile clips and copper wire.Adjust the position of the aluminum plate in the carbon counter electrode to face each other. Connect the aluminum plate to the positive terminal and connect the carbon counter electrode to the negative terminal of a direct current power supply. After applying a voltage of 20 volts, the aluminum plate goes from having a rough lustreless surface to having a mirror-like surface silver in color.To perform the primary anodization, pour one liter of the electrolyte into a two liter double jacket beaker. Immersed the polished aluminum plate and carbon counter electrode into the solution with crocodile clips in copper wire. Install a vertical shaft on a u-shaped pedestal.Attach an overhead stirrer and an impeller using metal clamps. Position the propeller of the impeller near the lower end of both electrodes. Set the rotation speed of the overhead stir between 200 and 300 rpm and apply a voltage of 195 volts under stirring for 16 hours.Following primary anodization, the color of the aluminum plate changes from silver to gray. To perform alumina itching, immerse the anodized aluminum plate in the etching solution. Sealed the top of the beaker with aluminum foil and allowed to stir for at least 10 hours.During the etching step, the color of the aluminum plate changes from gray to white. For the secondary anodization, set up the same experimental conditions as the primary anodization and again apply a voltage of 195 volts for six hours. Following secondary anodization, the color of the aluminum plate changes from white back to gray.To perform the gradient pore widening, first connect the double jacket beaker containing a phosphoric acid solution to the circulator and set the temperature at 30 degrees Celsius. Place a linear moving stage vertically next to the beaker and attach a bracket to the moving part of the linear stage. Set the moving part of the linear stage to the home position.Attach the clip of the bracket and load the anodized aluminum plate. Manipulate the position of the aluminum plate manually so that the aluminum plate will come right above the surface of the solution. Gradually immerse the aluminum plate into the solution at a speed of four point eight six microns per second for 120 minutes to make a 35-millimeter AAO mold with a size gradient from 120 nanometers to 200 nanometers.Start a stopwatch at the moment the aluminum plate touches the surface of the solution. After 100 minutes have passed, half of the AAO mold should be in the solution. To make GP 200 to 280 and GP 280 to 360 molds, Immersed the entire area of GP 120 to 200 mold in the pore widening solution for two to four hours respectively.Immerse the AAO mold and piranha solution for 30 seconds using a non-metallic tweezer. Rinse the AAO mold several times with deionized water. Soak the mold in deionized water for 30 minutes and put in methyl alcohol for another 30 minutes.Completely dried the AAO mold under vacuum for three hours. For self-assembled monolayers deposition, immerse the AAO mold in 57 milliliters of filtered and hexane and a 100 milliliter beaker. Then add three milliliters of HDFS stock solution to the N hexane to make a 2.9 millimolar HDFS solution and wait 10 minutes for the reaction to proceed.After transferring the AAO mold to fresh and hexane, soaked the AAO mold in 60 milliliters of methoxy-nonafluorobutane. Ultrasonically clean the AAO mold in a beaker for 10 seconds per one time to remove physically adsorbed HDFS molecules. Repeat the cleaning procedure 10 times before drying the AAO mold under vacuum for 24 hours.Cut a one point one millimeter thick polystyrene sheet to a size of two point nine millimeters wide by three point seven millimeters long using a printed circuit board cutter. Working in a clean room, cut the AAO mold 35 millimeters from the bottom using a nipper. Mark the sample name and data manufacturer on the back.Clean an eight point zero inch wafer with the small dose of ethyl alcohol, then put the polystyrene sheets on the wafer and mount the AAO mold. Next, put the bottom film in the drawer of a thermal imprinter and attach the top film to the gasket, then put the wafer on the bottom film and place the gasket on the wafer. Make sure that there is no dust on the wafer.After closing the drawer of the thermal and printer apply 165 degrees Celsius of heat and 620 point five/two kilopascal of pressure from 100 seconds. Then cool the sample to room temperature. Once cool, vent the chamber and the pressure will go down to zero kilo Pascal.Gently twist the polystyrene sheet to release the AAO mold. Collect 50 milliliters of human blood using a heparin inhibitor tube. Put six milliliters of hydrophilic polysaccharide solution in a 15 milliliter tube and add eight milliliters of blood to the hydrophilic polysaccharide solution.A blood needs to be collected immediately and slowly added on top of the hydrophilic polysaccharide solution. After centrifuging the tube at 1020 times G for 20 minutes to pellet the cells, harvest the opaque cell layer and transferred to a new 15 milliliter tube. At 10 milliliters of PBS containing 10%FBS in centrifuge the tube at 1020 times G for 10 minutes to pellet the cells.Remove the supernatant and add red blood cell lysis buffer. After incubating on ice for five minutes at PBS containing 10%FBS and centrifuge the tube at 1020 times G for five minutes to pellet the cells. Remove the supernatant and add one milliliter of endothelial cell expansion medium supplemented with 10%FBS.Seed eight point zero million cells per well for each collagen coded dish. Induce the human and ethereal colony forming cells as described in the text protocol and grow the cells to passage seven for further experiments. Next, coat the gradient nano pattern plates with one milliliter of zero point one percent protein coating solution in PBS for 10 minutes at room temperature.Make a suspension of human ECFCs from the culture dish by a standard cell splitting method using trypsin. After diluting the cell suspension to achieve the desired confluence, seed the human ECFCs cease on to the gradient nano pattern plates in a flat control. Culture the cells on flat or gradient nano pattern plates for two days in the incubator.These images show the AAO molds fabricated under three different pour widening conditions. One side with the shortest time immersed in the phosphoric acid etching solution has the smallest pore size, whereas the other side having the longest time in the etching solution has the largest pore size. Since the nano pattern was transferred to the polystyrene through the thermal imprinting method, nano pillar structures are generated on the polystyrene surface and the size gradient of the AAO mold is maintained in nano pattern plates.The confluent human ECFCs showed typical cobblestone like morphology inform a colony which can be easily distinguished under a phase contrast microscope. After two days of cultivation of human ECFCs on the flat in gradient nano pattern plates, significant filopodia outgrowth was observed in cells cultured on GP 120 to 200. Conversely, no remarkable change was observed in GP 200 to 280 or GP 280 to 360 in comparison with the flat control.This result indicates that the response of the cells is different depending on the size of the surface nano structure. There are many steps to fabricate a nano pattern plate. So it can be complicated at first, but once mastered, you will get down patterns with desires size gradient without any difficulties.After watching this video, you should have a great understanding of how to produce gradient nano pattern plates and the cultivate to human and the sillier colony-forming series on the nano pattern plate. Also this method is available to various types of series. This method can provide a bridge between material engineering and biotechnology that will help to understand the injections of cells and surface Nano topography.

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Research

JoVE Journal

Bioengineering

Fabrication of Micro-tissues using Modules of Collagen Gel Containing Cells

This protocol describes the fabrication of a type of micro-tissues called modules.  The module approach generates uniform, scalable and vascularized tissues.  The modules can be made of collagen as well as other gelable or crosslinkable materials.  They are approximately 2 mm in length and 0.7 mm in diameter upon fabrication but shrink in size with embedded cells or when the modules are coated with endothelial cells.  The modules individually are small enough that the embedded cells are within the diffusion limit of oxygen and other nutrients but modules can be packed together to form larger tissues that are perfusable.  These tissues are modular in construction because different cell types can be embedded in or coated on the modules before they are packed together to form complex tissues.  There are three main steps to making the modules: (1) neutralizing the collagen and embedding cells in it, (2) gelling the collagen in the tube and cutting the modules and (3) coating the modules with endothelial cells.

Creation of micro-tissues using cylindrical collagen gels, called modules, that contain embedded cells and which surface is coated with endothelial cells.

This protocol describes the fabrication of a type of micro-tissues called modules.  The module approach generates uniform, scalable and vascularized ...

Human Cartilage Tissue Fabrication Using Three-dimensional Inkjet Printing Technology

Bioprinting, which is based on thermal inkjet printing, is one of the most attractive enabling technologies in the field of tissue engineering and regenerative medicine. With digital control&#160;cells, scaffolds, and growth factors can be precisely deposited to the desired two-dimensional (2D) and three-dimensional (3D) locations rapidly. Therefore, this technology is an ideal approach to fabricate tissues mimicking their native anatomic structures. In order to engineer cartilage with native zonal organization, extracellular matrix composition (ECM), and mechanical properties, we developed a bioprinting platform using a commercial inkjet printer with simultaneous photopolymerization capable for 3D cartilage tissue engineering. Human chondrocytes suspended in poly(ethylene glycol) diacrylate (PEGDA) were printed for 3D neocartilage construction via layer-by-layer assembly. The printed cells were fixed at their original deposited positions, supported by the surrounding scaffold in simultaneous photopolymerization. The mechanical properties of the printed tissue were similar to the native cartilage. Compared to conventional tissue fabrication, which requires longer UV exposure, the viability of the printed cells with simultaneous photopolymerization was significantly higher. Printed neocartilage demonstrated excellent glycosaminoglycan (GAG) and collagen type II production, which was consistent with gene expression. Therefore, this platform is ideal for accurate cell distribution and arrangement for anatomic tissue engineering.

The methods described in this paper show how to convert a commercial inkjet printer into a bioprinter with simultaneous UV polymerization. The printer is capable of constructing 3D tissue structure with cells and biomaterials. The study demonstrated here constructed a 3D neocartilage.

Bioprinting, which is based on thermal inkjet printing, is one of the most attractive enabling technologies in the field of tissue engineering and ...

Polymeric Microneedle Array Fabrication by Photolithography

This manuscript describes the fabrication of polymeric microneedle (MN) arrays by photolithography. It involves a simple mold-free process by using a photomask consisting of embedded micro-lenses. Embedded micro-lenses were found to influence MN geometry (sharpness). Robust MN arrays with tip diameters ranging between 41.5 &#181;m &#177; 8.4 &#181;m and 71.6 &#181;m &#177; 13.7 &#181;m, with two different lengths (1,336 &#181;m &#177; 193 &#181;m and 957 &#181;m &#177; 171 &#181;m) were fabricated. These MN arrays may provide potential applications in delivery of low molecular and macromolecular therapeutic agents through skin.

Here, we present a protocol describing a mold-free fabrication process of the polymeric microneedles by photolithography.

This manuscript describes the fabrication of polymeric microneedle (MN) arrays by photolithography. It involves a simple mold-free process by using a ...

Biomembrane Fabrication by the Solvent-assisted Lipid Bilayer (SALB) Method

In order to mimic cell membranes, the supported lipid bilayer (SLB) is an attractive platform which enables in vitro investigation of membrane-related processes while conferring biocompatibility and biofunctionality to solid substrates. The spontaneous adsorption and rupture of phospholipid vesicles is the most commonly used method to form SLBs. However, under physiological conditions, vesicle fusion (VF) is limited to only a subset of lipid compositions and solid supports. Here, we describe a one-step general procedure called the solvent-assisted lipid bilayer (SALB) formation method in order to form SLBs which does not require vesicles. The SALB method involves the deposition of lipid molecules onto a solid surface in the presence of water-miscible organic solvents (e.g., isopropanol) and subsequent solvent-exchange with aqueous buffer solution in order to trigger SLB formation. The continuous solvent exchange step enables application of the method in a flow-through configuration suitable for monitoring bilayer formation and subsequent alterations using a wide range of surface-sensitive biosensors. The SALB method can be used to fabricate SLBs on a wide range of hydrophilic solid surfaces, including those which are intractable to vesicle fusion. In addition, it enables fabrication of SLBs composed of lipid compositions which cannot be prepared using the vesicle fusion method. Herein, we compare results obtained with the SALB and conventional vesicle fusion methods on two illustrative hydrophilic surfaces, silicon dioxide and gold. To optimize the experimental conditions for preparation of high quality bilayers prepared via the SALB method, the effect of various parameters, including the type of organic solvent in the deposition step, the rate of solvent exchange, and the lipid concentration is discussed along with troubleshooting tips. Formation of supported membranes containing high fractions of cholesterol is also demonstrated with the SALB method, highlighting the technical capabilities of the SALB technique for a wide range of membrane configurations.

Biomembrane Fabrication by the Solvent-assisted Lipid Bilayer SALB Method

We present an experimental protocol to form a supported lipid bilayer on solid substrates without using lipid vesicles. We demonstrate a one-step method to form a lipid bilayer on silicon dioxide and gold as well as supported membranes with cholesterol-enriched domain for various biological applications.

In order to mimic cell membranes, the supported lipid bilayer (SLB) is an attractive platform which enables in vitro investigation of membrane-related ...

An Additive Manufacturing Technique for the Facile and Rapid Fabrication of Hydrogel-based Micromachines with Magnetically Responsive Components

Polyethylene glycol (PEG)-based hydrogels are biocompatible hydrogels that have been approved for use in humans by the FDA. Typical PEG-based hydrogels have simple monolithic architectures and often function as scaffolding materials for tissue engineering applications. More sophisticated structures typically take a long time to fabricate and do not contain moving components. This protocol describes a photolithography method that allows for facile and rapid microfabrication of PEG structures and devices. This strategy involves an in-house developed fabrication stage that allows for the rapid fabrication of 3D structures by building upwards in a layer-by-layer fashion. Independent moving components can also be aligned and assembled onto support structures to form integrated devices. These independent components are doped with superparamagnetic iron oxide nanoparticles that are sensitive to magnetic actuation. In this manner, the fabricated devices can be actuated using external magnets to yield movement of the components within. Hence, this technique allows for the fabrication of sophisticated MEMS-like devices (micromachines) that are composed entirely out of a biocompatible hydrogel, able to function without an onboard power source, and respond to a contact-less method of actuation. This manuscript describes the fabrication of both the fabrication set-up as well as the step-by-step method for the microfabrication of these hydrogels-based MEMS-like devices.

An additive manufacturing strategy for processing UV-crosslinkable hydrogels has been developed. This strategy allows for the layer-by-layer assembly of microfabricated hydrogel structures as well as the assembly of independent components, yielding integrated devices containing moving components that are responsive to magnetic actuation.

Polyethylene glycol (PEG)-based hydrogels are biocompatible hydrogels that have been approved for use in humans by the FDA. Typical PEG-based hydrogels ...

Fabrication of Decellularized Cartilage-derived Matrix Scaffolds

Osteochondral defects lack sufficient intrinsic repair capacity to regenerate functionally sound bone and cartilage tissue. To this extent, cartilage research has focused on the development of regenerative scaffolds. This article describes the development of scaffolds that are completely derived from natural cartilage extracellular matrix, coming from an equine donor. Potential applications of the scaffolds include producing allografts for cartilage repair, serving as a scaffold for osteochondral tissue engineering, and providing in vitro models to study tissue formation. By decellularizing the tissue, the donor cells are removed, but many of the natural bioactive cues are thought to be retained. The main advantage of using such a natural scaffold in comparison to a synthetically produced scaffold is that no further functionalization of polymers is required to drive osteochondral tissue regeneration. The cartilage-derived matrix scaffolds can be used for bone and cartilage tissue regeneration in both in vivo and in vitro settings.

Decellularized cartilage-derived scaffolds can be used as a scaffold to guide cartilage repair and as a means to regenerate osteochondral tissue. This paper describes the decellularization process in detail and provides suggestions to use these scaffolds in in vitro settings.

Osteochondral defects lack sufficient intrinsic repair capacity to regenerate functionally sound bone and cartilage tissue. To this extent, cartilage ...

Standardized and Scalable Assay to Study Perfused 3D Angiogenic Sprouting of iPSC-derived Endothelial Cells In Vitro

Pre-clinical drug research of vascular diseases requires in vitro models of vasculature that are amendable to high-throughput screening. However, current in vitro screening models that have sufficient throughput only have limited physiological relevance, which hinders the translation of findings from in vitro to in vivo. On the other hand, microfluidic cell culture platforms have shown unparalleled physiological relevancy in vitro, but often lack the required throughput, scalability and standardization. We demonstrate a robust platform to study angiogenesis of endothelial cells derived from human induced pluripotent stem cells (iPSC-ECs) in a physiological relevant cellular microenvironment, including perfusion and gradients. The iPSC-ECs are cultured as 40 perfused 3D microvessels against a patterned collagen-1 scaffold. Upon the application of a gradient of angiogenic factors, important hallmarks of angiogenesis can be studied, including the differentiation into tip- and stalk cell and the formation of perfusable lumen. Perfusion with fluorescent tracer dyes enables the study of permeability during and after anastomosis of the angiogenic sprouts. In conclusion, this method shows the feasibility of iPSC-derived ECs in a standardized and scalable 3D angiogenic assay that combines physiological relevant culture conditions in a platform that has the required robustness and scalability to be integrated within the drug screening infrastructure.

This method describes the culture of iPSC-derived endothelial cells as 40 perfused 3D microvessels in a standardized microfluidic platform. This platform enables the study of gradient-driven angiogenic sprouting in 3D, including anastomosis and stabilization of the angiogenic sprouts in a scalable and high-throughput manner.

Pre-clinical drug research of vascular diseases requires in vitro models of vasculature that are amendable to high-throughput screening. However, current ...

Applications for Open Source Microplate-Compatible Illumination Panels

Microplates are commonly used in the modern laboratory environment for a wide variety of tasks both in small-scale laboratory benchtop operations as well as large-scale high-throughput screening (HTS) campaigns. Though laboratory automation has greatly increased the utility of microplates there remain instances where automation-based instrumentation is not feasible, cost-effective or compatible with microplate formatting needs. In these cases, microplates must be manually prepared. Problematic to manual microplate manipulations is that a number of difficulties can arise pertaining to the accurate tracking of sample operations, data record keeping and quality control (QC) inspection for well artifacts or formatting errors. As microplate well densities increase (i.e., 96-well, 384-well, 1536-well) the potential for introducing errors also drastically increases.&#160; Moreover, for small bench-top laboratory operations there exists a need to improve the ease and accuracy of sample handling in a cost-effective fashion. Herein, we describe a system that acts as a semi-automated pipetting guide referred to as the Microplate Assistive Pipetting Light Emitter (M.A.P.L.E.). &#160;M.A.P.L.E. has multiple uses for supporting compound hit-picking and microplate preparation for assay development in high-throughput screening or laboratory benchtop operations, as well as QC/quality assurance (QA) diagnostic evaluation of microplate quality or visualizing well formatting errors.

Microplate Assistive Pipetting Light Emitter (M.A.P.L.E.) is a computer-driven device that systematically illuminates microtiter wells to provide guidance for the manual preparation of microplates.&#160; M.A.P.L.E. improves the accuracy of microplate preparation while automating data recordkeeping. &#160;In addition, it can assist with examining microplate quality or aid in the detection of errors.&#160; &#160;

Microplates are commonly used in the modern laboratory environment for a wide variety of tasks both in small-scale laboratory benchtop operations as well ...

Scalable Generation of Mature Cerebellar Organoids from Human Pluripotent Stem Cells and Characterization by Immunostaining

The cerebellum plays a critical role in the maintenance of balance and motor coordination, and a functional defect in different cerebellar neurons can trigger cerebellar dysfunction. Most of the current knowledge about disease-related neuronal phenotypes is based on postmortem tissues, which makes understanding of disease progression and development difficult. Animal models and immortalized cell lines have also been used as models for neurodegenerative disorders. However, they do not fully recapitulate human disease. Human induced pluripotent stem cells (iPSCs) have great potential for disease modeling and provide a valuable source for regenerative approaches. In recent years, the generation of cerebral organoids from patient-derived iPSCs improved the prospects for neurodegenerative disease modeling. However, protocols that produce large numbers of organoids and a high yield of mature neurons in 3D culture systems are lacking. The protocol presented is a new approach for reproducible and scalable generation of human iPSC-derived organoids under chemically-defined conditions using scalable single-use bioreactors, in which organoids acquire cerebellar identity. The generated organoids are characterized by the expression of specific markers at both mRNA and protein level. The analysis of specific groups of proteins allows the detection of different cerebellar cell populations, whose localization is important for the evaluation of organoid structure. Organoid cryosectioning and further immunostaining of organoid slices are used to evaluate the presence of specific cerebellar cell populations and their spatial organization.

This protocol describes a dynamic culture system to produce controlled size aggregates of human pluripotent stem cells and further stimulate differentiation in cerebellar organoids under chemically-defined and feeder-free conditions using a single-use bioreactor.

The cerebellum plays a critical role in the maintenance of balance and motor coordination, and a functional defect in different cerebellar neurons can ...

Manganese Oxide Nanoparticle Synthesis by Thermal Decomposition of Manganese(II) Acetylacetonate

For biomedical applications, metal oxide nanoparticles such as iron oxide and manganese oxide (MnO), have been used as biosensors and contrast agents in magnetic resonance imaging (MRI). While iron oxide nanoparticles provide constant negative contrast on MRI over typical experimental timeframes, MnO generates switchable positive contrast on MRI through dissolution of MnO to Mn2+ at low pH within cell endosomes to &#8216;turn ON&#8217; MRI contrast. This protocol describes a one-pot synthesis of MnO nanoparticles formed by thermal decomposition of manganese(II) acetylacetonate in oleylamine and dibenzyl ether. Although running the synthesis of MnO nanoparticles is simple, the initial experimental setup can be difficult to reproduce if detailed instructions are not provided. Thus, the glassware and tubing assembly is first thoroughly described to allow other investigators to easily reproduce the setup. The synthesis method incorporates a temperature controller to achieve automated and precise manipulation of the desired temperature profile, which will impact resulting nanoparticle size and chemistry. The thermal decomposition protocol can be readily adapted to generate other metal oxide nanoparticles (e.g., iron oxide) and to include alternative organic solvents and stabilizers (e.g., oleic acid). In addition, the ratio of organic solvent to stabilizer can be changed to further impact nanoparticle properties, which is shown herein. Synthesized MnO nanoparticles are characterized for morphology, size, bulk composition, and surface composition through transmission electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy, respectively. The MnO nanoparticles synthesized by this method will be hydrophobic and must be further manipulated through ligand exchange, polymeric encapsulation, or lipid capping to incorporate hydrophilic groups for interaction with biological fluids and tissues.

Manganese Oxide Nanoparticle Synthesis by Thermal Decomposition of ManganeseII Acetylacetonate

This protocol details a facile, one-pot synthesis of manganese oxide (MnO) nanoparticles by thermal decomposition of manganese(II) acetylacetonate in the presence of oleylamine and dibenzyl ether. MnO nanoparticles have been utilized in diverse applications including magnetic resonance imaging, biosensing, catalysis, batteries, and waste water treatment.

For biomedical applications, metal oxide nanoparticles such as iron oxide and manganese oxide (MnO), have been used as biosensors and contrast agents in ...