这项研究由科学、ICT 和未来规划部 (NRF-2014R1A1A2057527 和 NRF-2016R1D1A1B03934418) 资助的韩国国家研究基金会 (NRF) 支持。

1. 通过孔阵列铝板和磁铁阵列的制备
<ol><li>准备两个50毫米 x 50 毫米 (或更大) 的铝板。每个板材的厚度为300µm, 是珠粒直径的一半。</li>
	<li>在其中一个铝板上形成一个 30 x 30 通孔阵列, 使用带有Φ550µm 微钻头的 CNC 旋转雕刻机, 其转速为30毫米/秒, 主轴速度为 8000 RPM。每个孔之间的距离 (中心到中心) 是 1 mm (图 1a和图 2a, i)。</li>
	<li>使用与 1.2 (图 1a和图 2a, ii) 中描述的程序相同的步骤, 在其他铝板上形成一个 30 x 30 阵列的Φ750-µm 通孔。</li>
	<li>在两个铝板的四角上, 使用粘胶带和形成Φ3 mm 对齐孔, 以彼此连接这两个板块。</li>
	<li>在15% 硫酸中浸泡12小时的铝板以清洁其表面。由于铝表面的薄层氧化铝使其具有耐腐蚀性, 因此该酸处理不会改变板材的孔径和厚度。</li>
	<li>形成一个 30 x 30 阵列的1个 1 x 1 毫米钕磁铁 (具有磁性强度为 0.363 N)。确保每个磁铁是相反的极性对它的邻居。为了防止磁体阵列的破裂或散射, 使用双面胶带 (图 2a、 iii 和嵌入图 2) 将 30 x 30 mm 的铝板连接到磁体阵列的底部。</li>
</ol>2. 磁珠捕集工艺
<ol><li>对齐和堆叠两个铝板 (顶板: 750-µm 孔板, 底板: 550-µm 孔板) 使用准备的对准孔在每个板块的四角 (图 1b)。</li>
	<li>通过将 M3 螺栓插入对准孔中, 将两个板锁定在一起, 然后用螺母固定螺栓 (图 1b)。</li>
	<li>堆叠在准备好的磁铁阵列上的铝板组件 (图 1b, 2b和2c)。在堆叠过程中, 将磁体阵列与铝板上的孔阵列对齐。然后使用粘胶带固定磁铁阵列的位置。</li>
	<li>在板组件上放置足够数量的φ mm SUJ2 钢珠, 并使用丙烯 (或非金属) 板对珠子进行操作, 使珠子在每个孔 (图 1c、 1d和1e) 同时被困住去除未在孔中的多余的珠子。</li>
	<li>小心取下顶部板, 以避免不必要的散射和错位的珠子 (图 1f)。</li>
</ol>3. 凹微制造
<ol><li>移动凹微模具, 生产步骤2.1 至 2.5, 以上, 以培养皿。</li>
	<li>混合烷 (硅橡胶) 单体和固化剂根据制造商的指示19与一个硅氧烷单体: 固化剂比10:1。</li>
	<li>通过使用干燥和真空泵来除去在该混合物中被困住的气泡, 以消除气体的混合物。</li>
	<li>使用与 3.3 (图 1f) 中描述的过程相同的步骤, 将该混合物倒入凹微模和脱气中。</li>
	<li>在80° c 的板上烘烤 2 h 的硅氧烷混合物, 形成一个珠嵌入的硅橡胶衬底 (图 1g)。</li>
	<li>从模具 (图 1g) 中卸下固化的硅基板。在去除过程中, 用洗涤瓶喷涂甲醇从模具中分离出硅烷基板。</li>
	<li>使用 15 mm x 2 mm 磁铁, 从硅基板上取下被夹住的钢珠 (图 1h)。在这个过程中, 任何足够强的磁铁从硅氧烷基板中提取珠子都可以使用。</li>
</ol>4. 球体培养
<ol><li>在本研究中, 用 24-井板上的Φ14 mm 活检穿孔, 切割凹微图案的硅橡胶衬底。</li>
	<li>在121° c 和 15 psi 的高压灭菌器中消毒所产生的Φ14 mm 的硅基板。</li>
	<li>将灭菌后的硅基板置于24井盘中。</li>
	<li>用 4% (w/v) pluronic F-127 溶液将整个硅烷基板涂上一整夜, 防止细胞附着在微表面。在涂层过程中, 通过移或使用超声波清洗器, 去除凹 microwells 中的气泡。</li>
	<li>使用磷酸盐缓冲盐水 (PBS) 冲洗 F-127 溶液三次。</li>
	<li>种子1毫升的细胞介质 (Dulbecco 氏改良的鹰培养基) 解决方案 (其中包含 2 x 106细胞) 在硅烷基板上。请注意, 播种密度可以根据目标球体的大小和/或目标细胞类型而改变。在这里, 脂肪来源的干细胞 (ASC) 被使用。</li>
	<li>用1000µL 吸管抽吸1毫升培养基, 以去除未被困在 microwells 中的多余细胞 (图 3)。</li>
	<li>孵育的细胞在36.5 ° c, 湿度的 > 95%, 和 5% CO2条件。在我们的研究中使用的陶瓷的情况下, 细胞聚集到一个球体在48小时。</li>
</ol>

<ol>
	<li>Fennema, E., Rivron, N., Rouwkema, J., van Blitterswijk, C., de Boer, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Spheroid+culture+as+a+tool+for+creating+3D+complex+tissues.">Spheroid culture as a tool for creating 3D complex tissues.</a> Trends Biotechnol. 31 (2), 108-115 (2013).</li><li>Djordjevic, B., Lange, C. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Hybrid+spheroids+as+a+tool+for+prediction+of+radiosensitivity+in+tumor+therapy.">Hybrid spheroids as a tool for prediction of radiosensitivity in tumor therapy.</a> Indian J Exp Biol. 42 (5), 443-447 (2004).</li><li>Takezawa, T., Yamazaki, M., Mori, Y., Yonaha, T., Yoshizato, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphological+and+immuno-cytochemical+characterization+of+a+hetero-spheroid+composed+of+fibroblasts+and+hepatocytes.">Morphological and immuno-cytochemical characterization of a hetero-spheroid composed of fibroblasts and hepatocytes.</a> J Cell Sci. 101 (3), 495-501 (1992).</li><li>Gottfried, E., Kunz-Schughart, L. A., Andreesen, R., Kreutz, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Brave+little+world:+spheroids+as+an+in+vitro+model+to+study+tumor-immune-cell+interactions.">Brave little world: spheroids as an in vitro model to study tumor-immune-cell interactions.</a> Cell Cycle. 5 (7), 691-695 (2006).</li><li>Zhang, X., 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=Development+of+an+in+vitro+multicellular+tumor+spheroid+model+using+microencapsulation+and+its+application+in+anticancer+drug+screening+and+testing.">Development of an in vitro multicellular tumor spheroid model using microencapsulation and its application in anticancer drug screening and testing.</a> Biotechnol Prog. 21 (4), 1289-1296 (2005).</li><li>Kim, B. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microwell-mediated+micro+cartilage-like+tissue+formation+of+adipose-derived+stem+cell.">Microwell-mediated micro cartilage-like tissue formation of adipose-derived stem cell.</a> Macromol Res. 22 (3), 287-296 (2014).</li><li>Fatehullah, A., Tan, S. H., Barker, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Organoids+as+an+in+vitro+model+of+human+development+and+disease.">Organoids as an in vitro model of human development and disease.</a> Nature cell biology. 18 (3), 246-254 (2016).</li><li>Yuhas, J. M., Li, A. P., Martinez, A. O., Ladman, A. 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+simplified+method+for+production+and+growth+of+multicellular+tumor+spheroids.">A simplified method for production and growth of multicellular tumor spheroids.</a> Cancer Res. 37 (10), 3639-3643 (1977).</li><li>Hamilton, G. A., Westmoreland, C., George, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+medium+composition+on+the+morphology+and+function+of+rat+hepatocytes+cultured+as+spheroids+and+monolayers.">Effects of medium composition on the morphology and function of rat hepatocytes cultured as spheroids and monolayers.</a> In Vitro Cell Dev Biol-Animal. 37 (10), 656-667 (2001).</li><li>Nyberg, S. L., 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,+large-scale+formation+of+porcine+hepatocyte+spheroids+in+a+novel+spheroid+reservoir+bioartificial+liver.">Rapid, large-scale formation of porcine hepatocyte spheroids in a novel spheroid reservoir bioartificial liver.</a> Liver Transplant. 11 (8), 901-910 (2005).</li><li>Lazar, 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=Extended+liver-specific+functions+of+porcine+hepatocyte+spheroids+entrapped+in+collagen+gel.">Extended liver-specific functions of porcine hepatocyte spheroids entrapped in collagen gel.</a> In Vitro Cell Dev Biol-Animal. 31 (5), 340-346 (1995).</li><li>Kelm, J. M., Timmins, N. E., Brown, C. J., Fussenegger, M., Nielsen, L. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Method+for+generation+of+homogeneous+multicellular+tumor+spheroids+applicable+to+a+wide+variety+of+cell+types.">Method for generation of homogeneous multicellular tumor spheroids applicable to a wide variety of cell types.</a> Biotechnol Bioeng. 83 (2), 173-180 (2003).</li><li>Lin, R. Z., Chang, H. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Recent+advances+in+three-dimensional+multicellular+spheroid+culture+for+biomedical+research.">Recent advances in three-dimensional multicellular spheroid culture for biomedical research.</a> Biotechnol J. 3 (9-10), 1172-1184 (2008).</li><li>Choi, Y. Y., 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=Controlled-size+embryoid+body+formation+in+concave+microwell+arrays.">Controlled-size embryoid body formation in concave microwell arrays.</a> Biomaterials. 31 (15), 4296-4303 (2010).</li><li>Hwang, J. W., 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=Functional+clustering+of+pancreatic+islet+cells+using+concave+microwell+array.">Functional clustering of pancreatic islet cells using concave microwell array.</a> Macromol Res. 19 (12), 1320-1326 (2011).</li><li>Wong, S. 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=Concave+microwell+based+size-controllable+hepatosphere+as+a+three-dimensional+liver+tissue+model.">Concave microwell based size-controllable hepatosphere as a three-dimensional liver tissue model.</a> Biomaterials. 32 (32), 8087-8096 (2011).</li><li>Yeon, S. 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=Application+of+concave+microwells+to+pancreatic+tumor+spheroids+enabling+anticancer+drug+evaluation+in+a+clinically+relevant+drug+resistance+model.">Application of concave microwells to pancreatic tumor spheroids enabling anticancer drug evaluation in a clinically relevant drug resistance model.</a> PloS one. 8 (9), (2013).</li><li>Park, J. Y., Hwang, C. M., Lee, S. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ice-lithographic+fabrication+of+concave+microwells+and+a+microfluidic+network.">Ice-lithographic fabrication of concave microwells and a microfluidic network.</a> Biomed Microdevices. 11 (1), 129-133 (2009).</li><li>Corning, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Sylgard 184 Silicone Elastomer. Technical Data Sheet. , (2008).</li><li>Giang, U. B. T., Lee, D., King, M. R., DeLouise, L. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfabrication+of+cavities+in+polydimethylsiloxane+using+DRIE+silicon+molds.">Microfabrication of cavities in polydimethylsiloxane using DRIE silicon molds.</a> Lab on a Chip. 7 (12), 1660-1662 (2007).</li><li>Choi, J. S., 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=Capture+and+culturing+of+single+microalgae+cells,+and+retrieval+of+colonies+using+a+perforated+hemispherical+microwell+structure.">Capture and culturing of single microalgae cells, and retrieval of colonies using a perforated hemispherical microwell structure.</a> RSC Advances. 4 (106), 61298-61304 (2014).</li><li>Zhong, K., Gao, Y., Li, F., Zhang, Z., Luo, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fabrication+of+PDMS+microlens+array+by+digital+maskless+grayscale+lithography+and+replica+molding+technique.">Fabrication of PDMS microlens array by digital maskless grayscale lithography and replica molding technique.</a> Optik. 125 (10), 2413-2416 (2014).</li><li>Lai, D., 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=Simple+multi-level+microchannel+fabrication+by+pseudo-grayscale+backside+diffused+light+lithography.">Simple multi-level microchannel fabrication by pseudo-grayscale backside diffused light lithography.</a> RSC advances. 3 (42), 19467-19473 (2013).</li><li>Pan, 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=Fabrication+of+a+3D+hair+follicle-like+hydrogel+by+soft+lithography.">Fabrication of a 3D hair follicle-like hydrogel by soft lithography.</a> J Biomed MAter Res A. 101 (11), 3159-3169 (2013).</li><li>Mori, R., Sakai, Y., Nakazawa, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Micropatterned+organoid+culture+of+rat+hepatocytes+and+HepG2+cells.">Micropatterned organoid culture of rat hepatocytes and HepG2 cells.</a> J Biosci Bioeng. 106 (3), 237-242 (2008).</li></ol>

作者没有利益冲突透露。

这种制作方法面临的主要挑战是在铝板的通孔阵列中的珠子的安全固定。为了解决这一难题, 以 30 x 30 磁铁阵列的形式使用磁力来稳固地固定珠子, 如图 6和7所示。磁体阵列的磁通密度与极性相反, 在每个磁体表面的中心最强。因为磁力的强度取决于磁通密度, 所以珠子被引导到每个磁铁的顶面中心, 在那里他们被放置在位置。如果使用一个大尺寸的磁铁 (5 厘米 x 5 cm x 1 厘?...

生长成球状形态的细胞比二维平面区域性1更类似于实体组织。考虑到这一优势, 采用椭球的方法来改善细胞与细胞相互作用的研究2,3, 免疫激活4, 药物筛选5, 和差异性6。此外, 椭球结合多种细胞类型最近已应用于 organoids (近生理三维 (3D) 组织), 这是非常有用的研究人类发展和疾病7。几种方法已被用于生产椭球。最简单的方法是利用非粘合表面, 使细胞聚集在一起, 形成椭球。培养皿可以用牛血清白蛋白、pluronic F-127 或疏水性聚合物 (如聚 2-乙甲基丙烯酸酯) 来处理, 使其表面不粘附8, 9。微调烧瓶方法是另一种众所周知的生产大量椭球10,11的方式。在这种方法中, 细胞通过搅拌来保持悬浮, 以防止它们附着在基体上。相反, 浮动单元格聚合以形成椭球。无粘结面法和微调瓶法均能产生大量的椭球。但是, 它们受到限制, 包括控制球体尺寸的困难, 以及每个球体的跟踪和监测。作为对此类问题的一种补救方法, 另一种球形生产方式, 即悬挂跌落法可以采用12。这包括将细胞悬浮液沉淀在培养皿盖子的下侧。这些下落通常是15到30µL 在大小并且包含大约300到3000个细胞13。当盖子是倒置的, 下落由表面张力举行。每个下落的微重力环境集中细胞, 然后形成唯一椭球在自由的液体空气接口。悬挂下降法的优点是它提供了一个受控的大小分布, 而它很容易跟踪和监测每个球体, 相对于非胶粘剂表面和微调烧瓶的方法。然而, 这种方法在椭球的大量生产和生产过程本身是过度劳动密集型的情况下产生了一个不利因素。
微阵列是一个平板, 有许多微尺寸的井, 每一个直径不等, 从100到1000µm。在使用 microwells 时, 球体的生产原理与非粘性表面方法相似。好处包括 microwells 提供空间之间的 microwells 分离的细胞或椭球, 这样, 它是易于控制的球体大小, 同时也使它易于监测每个单一的球体。随着大量的 microwells, 高吞吐量球体的生产也成为可能。microwells 的另一个优势是根据用户独特的实验目的, 选择不同形状的水井 (六面体、圆柱形、三角形棱柱)。然而, 一般来说, 一个三维 (3D) 凹 (或半球) 形状被认为是最适合生产统一尺寸的单椭球。因此, 凹 microwells 的用处已经报告了许多细胞生物学研究, 如那些检测胚胎干细胞分化的心肌细胞14, 胰岛细胞簇的胰岛素分泌,15,肝细胞酶活性为16, 肿瘤耐药性椭球17。
不幸的是, 制作 microwells 往往需要专门的微设施;传统的光刻方法需要曝光和开发设备, 而反应离子蚀刻的方法需要等离子和离子束设备。这类设备费用高昂, 加上复杂的制作过程, 给无法进入微的生物学家带来了高门槛。为了克服这些问题, 提出了其他成本效益高的方法, 如冰光刻18 (使用冷冻水滴) 和柔性膜法14 (使用膜、通孔衬底和真空)。然而, 这些方法也有严重的缺点, 如难以控制的模式大小, 实现高宽比, 和生产大面积 microwells。
为了克服上述问题, 我们提出了一种新的凹微制造方法, 利用孔基板、钢珠和磁铁阵列。利用这种方法, 利用磁力辅助的自锁金属珠 (图 1) 的机理, 可以制作数以百计的凹球形 microwells。制作过程涉及使用极少数昂贵和复杂的设施, 不需要许多先进的技能。因此, 即使是不熟练的人也很容易承担这种制作方法。为了证明所提出的方法, 在凹 microwells 培养人脂肪干细胞, 产生椭球。

<table border="0" cellpadding="0" cellspacing="0" width="612">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">CNC rotary engraver</td>
			<td style="width:111px;">Roland DGA</td>
			<td style="width:119px;">EGX-350</td>
			<td style="width:167px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Micro drill bit</td>
			<td style="width:111px;">HAM Pr&#228;zision</td>
			<td style="width:119px;">30-1301 TA</td>
			<td>&#934; 0.55 and 0.75 mm</td>
		</tr>
		<tr height="84">
			<td height="84" style="height:84px;width:216px;">Sulfuric acid 98%</td>
			<td style="width:111px;">Daejung</td>
			<td style="width:119px;">7683-4100</td>
			<td style="width:167px;">For cleaning aluminum plate. 
			Dilute with distilled water with 15% solution</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Neodymium magnet</td>
			<td style="width:111px;">Supermagnete</td>
			<td>W-01-N</td>
			<td>1 x 1 x 1 mm</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Bearing ball</td>
			<td style="width:111px;">Agami Modeling</td>
			<td style="width:119px;">SUJ2</td>
			<td>&#934; 600 &#956;m steel bead</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Polydimethylsiloxane (PDMS)</td>
			<td style="width:111px;">Dowcorning</td>
			<td style="width:119px;">Sylgard 184</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Pluronic F-127</td>
			<td style="width:111px;">Sigma Aldrich</td>
			<td style="width:119px;">p2443</td>
			<td>Dilute with phosphate buffered saline to 4% (w/v) solution</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Dulbecco&#39;s modified eaggle&#39;s medium (DMEM)</td>
			<td style="width:111px;">ATCC</td>
			<td style="width:119px;">30-2002</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Dulbecco&#39;s phosphate buffered saline (D-PBS)</td>
			<td style="width:111px;">ATCC</td>
			<td style="width:119px;">30-2200</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Fetal bovine serum</td>
			<td style="width:111px;">ATCC</td>
			<td style="width:119px;">30-2020</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Adipose-derived mesenchymal stem cells</td>
			<td style="width:111px;">ATCC</td>
			<td style="width:119px;">ATCC PCS-500-011</td>
			<td></td>
		</tr>
	</tbody>
</table>

a paired bead and magnet array for molding microwells with variable concave geometries

椭球区域性是理解细胞行为的有用工具, 因为它提供了一个在体内类似的三维环境。各种球体的生产方法, 如无粘结表面, 微调烧瓶, 悬挂滴, 和 microwells 已被用于研究细胞间的相互作用, 免疫活化, 药物筛选, 干细胞分化, 和化生成。在这些方法中, microwells 与三维凹几何已经得到了科学家和工程师的注意, 由于他们的优势, 统一大小的球体生成和轻松的反应, 个别椭球可以监测.尽管提出了使用柔性膜和冰光刻等成本效益高的方法, 但这些技术存在着严重的缺点, 如难以控制模式尺寸、实现较高的长宽比和生产大面积的 microwells。针对这些问题, 提出了一种在不需要复杂的高成本设备的情况下制作凹 microwells 的鲁棒方法。该方法利用了 30 x 30 通孔阵列、几百微米级的钢珠和磁力, 在 3 cm x 3 cm 烷 (microwells) 基底上制造了900个。为了证明我们的方法对细胞生物学应用的适用性, 我们培养脂肪干细胞3天, 成功地生产椭球使用我们的微平台。此外, 我们进行了一个静磁场模拟研究的机制, 即磁力被用来捕获钢珠在通孔。我们认为, 所提出的微制备方法可以应用于许多基于球体的细胞研究, 如药物筛选、组织再生、干细胞分化和肿瘤转移。

通过以下步骤2.1 到 3.7, 成功地制作了凸模和微模式。(图 4)。商业钢珠被困在 30 x 30 通孔阵列。珠子被紧紧地抱着, 珠子和相应的通孔之间没有缝隙 (图 4a)。预制凹微的形状为凹半球形, 直径为600µm, 与钢珠相同 (图 4b)。凹微的横截面 (图 4c) 显示相邻微的距离为1毫米 (中心至中心), 与?...

Watch this Scientific Journal Video about A Paired Bead and Magnet Array for Molding Microwells with Variable Concave Geometries at JoVE.com

A Paired Bead and Magnet Array for Molding Microwells with Variable Concave Geometries

本文介绍了一种在不需要复杂的高成本设备的情况下, 制作凹 microwells 的鲁棒方法。采用磁力、钢珠和通孔阵列, 在 3 cm x 3 cm 烷 (microwells) 衬底上形成几百个。

变凹形形状 Microwells 的配对磁珠和磁体阵列

A spheroid culture is a useful tool for understanding cellular behavior in that it provides an in vivo-like three-dimensional environment. Various ...

a-paired-bead-magnet-array-for-molding-microwells-with-variable

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8.6K 次观看.  Chung-Ang University. 本文介绍了一种在不需要复杂的高成本设备的情况下, 制作凹 microwells 的鲁棒方法。采用磁力、钢珠和通孔阵列, 在 3 cm x 3 cm 烷 (microwells) 衬底上形成几百个。

视频: A Paired Bead and Magnet Array for Molding Microwells with Variable Concave Geometries

Investigating Receptor-ligand Systems of the Cellulosome with AFM-based Single-molecule Force Spectroscopy

Cellulosomes are discrete multienzyme complexes used by a subset of anaerobic bacteria and fungi to digest lignocellulosic substrates. Assembly of the enzymes onto the noncatalytic scaffold protein is directed by interactions among a family of related receptor-ligand pairs comprising interacting cohesin and dockerin modules. The extremely strong binding between cohesin and dockerin modules results in dissociation constants in the low picomolar to nanomolar range, which may hamper accurate off-rate measurements with conventional bulk methods. Single-molecule force spectroscopy (SMFS) with the atomic force microscope measures the response of individual biomolecules to force, and in contrast to other single-molecule manipulation methods (i.e.&#160;optical tweezers), is optimal for studying high-affinity receptor-ligand interactions because of its ability to probe the high-force regime (&#62;120 pN). Here we present our complete protocol for studying cellulosomal protein assemblies at the single-molecule level. Using a protein topology derived from the native cellulosome, we worked with enzyme-dockerin and carbohydrate binding module-cohesin (CBM-cohesin) fusion proteins, each with an accessible free thiol group at an engineered cysteine residue. We present our site-specific surface immobilization protocol, along with our measurement and data analysis procedure for obtaining detailed binding parameters for the high-affinity complex. We demonstrate how to quantify single subdomain unfolding forces, complex rupture forces, kinetic off-rates, and potential widths of the binding well. The successful application of these methods in characterizing the cohesin-dockerin interaction responsible for assembly of multidomain cellulolytic complexes is further described.

Cellulosomes are multienzyme complexes designed for digesting cellulose. AFM-based SMFS was used to study the mechanical properties and folding configuration of cellulosome-associated protein assemblies. We present a complete workflow for protein immobilization, data acquisition, and data analysis to study the interactions of individual receptor-ligand complexes involved in cellulosome assembly.

调查纤维素酶与基于AFM的单分子力谱受体 - 配体系统

Cellulosomes are discrete multienzyme complexes used by a subset of anaerobic bacteria and fungi to digest lignocellulosic substrates. Assembly of the ...

科研

生物工程

Microfluidic Fabrication of Polymeric and Biohybrid Fibers with Predesigned Size and Shape

A &#8220;sheath&#8221; fluid passing through a microfluidic channel at low Reynolds number can be directed around another &#8220;core&#8221; stream and used to dictate the shape as well as the diameter of a core stream.&#160;Grooves in the top and bottom of a microfluidic channel were designed to direct the sheath fluid and shape the core fluid.&#160;By matching the viscosity and hydrophilicity of the sheath and core fluids, the interfacial effects are minimized and complex fluid shapes can be formed.&#160;Controlling the relative flow rates of the sheath and core fluids determines the cross-sectional area of the core fluid.&#160;Fibers have been produced with sizes ranging from 300 nm to ~1 mm, and fiber cross-sections can be round, flat, square, or complex as in the case with double anchor fibers. Polymerization of the core fluid downstream from the shaping region solidifies the fibers.&#160;Photoinitiated click chemistries are well suited for rapid polymerization of the core fluid by irradiation with ultraviolet light.&#160;Fibers with a wide variety of shapes have been produced from a list of polymers including liquid crystals, poly(methylmethacrylate), thiol-ene and thiol-yne resins, polyethylene glycol, and hydrogel derivatives. Minimal shear during the shaping process and mild polymerization conditions also makes the fabrication process well suited for encapsulation of cells and other biological components.

Two adjacent fluids passing through a grooved microfluidic channel can be directed to form a sheath around a prepolymer core; thereby&#160;determining both shape and cross-section. Photoinitiated polymerization, such as thiol click chemistry, is well suited for rapidly solidifying the core fluid into a microfiber with predetermined size and shape.

预设计尺寸和形状的聚合物纤维和生物贿赂纤维的微流体制造

A &#8220;sheath&#8221; fluid passing through a microfluidic channel at low Reynolds number can be directed around another &#8220;core&#8221; stream and ...

Rapid and Low-cost Prototyping of Medical Devices Using 3D Printed Molds for Liquid Injection Molding

Biologically inert elastomers such as silicone are favorable materials for medical device fabrication, but forming and curing these elastomers using traditional liquid injection molding processes can be an expensive process due to tooling and equipment costs. As a result, it has traditionally been impractical to use liquid injection molding for low-cost, rapid prototyping applications. We have devised a method for rapid and low-cost production of liquid elastomer injection molded devices that utilizes fused deposition modeling 3D printers for mold design and a modified desiccator as an injection system. Low costs and rapid turnaround time in this technique lower the barrier to iteratively designing and prototyping complex elastomer devices. Furthermore, CAD models developed in this process can be later adapted for metal mold tooling design, enabling an easy transition to a traditional injection molding process. We have used this technique to manufacture intravaginal probes involving complex geometries, as well as overmolding over metal parts, using tools commonly available within an academic research laboratory. However, this technique can be easily adapted to create liquid injection molded devices for many other applications.

We have devised a method for low-cost and rapid prototyping of liquid elastomer rubber injection molded devices by using fused deposition modeling 3D printers for mold design and a modified desiccator as a liquid injection system.

医疗器械的使用3D印刷模具的液体注射成型快速，低成本原型

Biologically inert elastomers such as silicone are favorable materials for medical device fabrication, but forming and curing these elastomers using ...

Bead Aggregation Assays for the Characterization of Putative Cell Adhesion Molecules

Cell-cell adhesion is fundamental to multicellular life and is mediated by a diverse array of cell surface proteins. However, the adhesive interactions for many of these proteins are poorly understood. Here we present a simple, rapid method for characterizing the adhesive properties of putative homophilic cell adhesion molecules. Cultured HEK293 cells are transfected with DNA plasmid encoding a secreted, epitope-tagged ectodomain of a cell surface protein. Using functionalized beads specific for the epitope tag, the soluble, secreted fusion protein is captured from the culture medium. The coated beads can then be used directly in bead aggregation assays or in fluorescent bead sorting assays to test for homophilic adhesion. If desired, mutagenesis can then be used to elucidate the specific amino acids or domains required for adhesion. This assay requires only small amounts of expressed protein, does not require the production of stable cell lines, and can be accomplished in 4 days.

Here we present a simple, rapid method for characterizing the intrinsic adhesive properties of putative cell adhesion molecules. The secreted, epitope-tagged ectodomain of a cell adhesion molecule is captured from the culture medium on small, uniform functionalized beads. These beads can then be used immediately in simple bead aggregation assays.

珠聚集测定假定的细胞粘附分子的表征

Cell-cell adhesion is fundamental to multicellular life and is mediated by a diverse array of cell surface proteins. However, the adhesive interactions ...

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.

聚合物微针阵列制造用光刻

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

Multi-step Variable Height Photolithography for Valved Multilayer Microfluidic Devices

Microfluidic systems have enabled powerful new approaches to high-throughput biochemical and biological analysis. However, there remains a barrier to entry for non-specialists who would benefit greatly from the ability to develop their own microfluidic devices to address research questions. Particularly lacking has been the open dissemination of protocols related to photolithography, a key step in the development of a replica mold for the manufacture of polydimethylsiloxane (PDMS) devices. While the fabrication of single height silicon masters has been explored extensively in literature, fabrication steps for more complicated photolithography features necessary for many interesting device functionalities (such as feature rounding to make valve structures, multi-height single-mold patterning, or high aspect ratio definition) are often not explicitly outlined. 
Here, we provide a complete protocol for making multilayer microfluidic devices with valves and complex multi-height geometries, tunable for any application. These fabrication procedures are presented in the context of a microfluidic hydrogel bead synthesizer and demonstrate the production of droplets containing polyethylene glycol (PEG diacrylate) and a photoinitiator that can be polymerized into solid beads. This protocol and accompanying discussion provide a foundation of design principles and fabrication methods that enables development of a wide variety of microfluidic devices. The details included here should allow non-specialists to design and fabricate novel devices, thereby bringing a host of recently developed technologies to their most exciting applications in biological laboratories.

Multilayer microfluidic devices often involve the fabrication of master molds with complex geometries for functionality. This article presents a complete protocol for multi-step photolithography with valves and variable height features tunable to any application. As a demonstration, we fabricate a microfluidic droplet generator capable of producing hydrogel beads.

多级可变高度的光刻多层带瓣微流体装置

Microfluidic systems have enabled powerful new approaches to high-throughput biochemical and biological analysis. However, there remains a barrier to ...

Microfluidic Platform with Multiplexed Electronic Detection for Spatial Tracking of Particles

Microfluidic processing of biological samples typically involves differential manipulations of suspended particles under various force fields in order to spatially fractionate the sample based on a biological property of interest. For the resultant spatial distribution to be used as the assay readout, microfluidic devices are often subjected to microscopic analysis requiring complex instrumentation with higher cost and reduced portability. To address this limitation, we have developed an integrated electronic sensing technology for multiplexed detection of particles at different locations on a microfluidic chip. Our technology, called Microfluidic CODES, combines Resistive Pulse Sensing with Code Division Multiple Access to compress 2D spatial information into a 1D electrical signal. In this paper, we present a practical demonstration of the Microfluidic CODES technology to detect and size cultured cancer cells distributed over multiple microfluidic channels. As validated by the high-speed microscopy, our technology can accurately analyze dense cell populations all electronically without the need for an external instrument. As such, the Microfluidic CODES can potentially enable low-cost integrated lab-on-a-chip devices that are well suited for the point-of-care testing of biological samples.

We demonstrate a microfluidic platform with an integrated surface electrode network that combines resistive pulse sensing (RPS) with code division multiple access (CDMA), to multiplex detection and sizing of particles in multiple microfluidic channels.

与复用电子检测的粒子的空间跟踪微流体平台

Microfluidic processing of biological samples typically involves differential manipulations of suspended particles under various force fields in order to ...

Assembly and Tracking of Microbial Community Development within a Microwell Array Platform

The development of microbial communities depends on a combination of complex deterministic and stochastic factors that can dramatically alter the spatial distribution and activities of community members. We have developed a microwell array platform that can be used to rapidly assemble and track thousands of bacterial communities in parallel. This protocol highlights the utility of the platform and describes its use for optically monitoring the development of simple, two-member communities within an ensemble of arrays within the platform. This demonstration uses two mutants of Pseudomonas aeruginosa, part of a series of mutants developed to study Type VI secretion pathogenicity. Chromosomal inserts of either mCherry or GFP genes facilitate the constitutive expression of fluorescent proteins with distinct emission wavelengths that can be used to monitor community member abundance and location within each microwell. This protocol describes a detailed method for assembling mixtures of bacteria into the wells of the array and using time-lapse fluorescence imaging and quantitative image analysis to measure the relative growth of each member population over time. The seeding and assembly of the microwell platform, the imaging procedures necessary for the quantitative analysis of microbial communities within the array, and the methods that can be used to reveal interactions between microbial species area all discussed.

The development of microbial communities depends on a combination of factors, including environmental architecture, member abundance, traits, and interactions. This protocol describes a synthetic, microfabricated environment for the simultaneous tracking of thousands of communities contained in femtoliter wells, where key factors such as niche size and confinement can be approximated.

微孔阵列平台中微生物群落发展的组装与跟踪

The development of microbial communities depends on a combination of complex deterministic and stochastic factors that can dramatically alter the spatial ...

Visual Detection of Multiple Nucleic Acids in a Capillary Array

Multi-target, short time, and resource-affordable methodologies for the detection of multiple nucleic acids in a single, easy to operate test are urgently needed in disease diagnosis, microbial monitoring, genetically modified organism (GMO) detection, and forensic analysis. We have previously described the platform called CALM (Capillary Array-based Loop-mediated isothermal amplification for Multiplex visual detection of nucleic acids). Herein, we describe improved fabrication and performance processes for this platform. Here, we apply a small, ready-to-use cassette assembled by capillary array for multiplex visual detection of nucleic acids. The capillary array is pre-treated into a hydrophobic and hydrophilic pattern before fixing loop-mediated isothermal amplification (LAMP) primer sets in capillaries. After assembly of the loading adaptor, LAMP reaction mixture is loaded and isolated into each capillary, due to capillary force by a single pipetting step. The LAMP reactions are performed in parallel in the capillaries. The results are visually read out by illumination with a hand-held UV flashlight. Using this platform, we demonstrate monitoring of 8 frequently appearing elements and genes in GMO samples with high specificity and sensitivity. In summary, the platform described herein is intended to facilitate the detection of multiple nucleic acids. We believe it will be widely applicable in fields where high-throughput nucleic acid analysis is required.

This protocol describes the fabrication of a small, ready-to-use cassette that can be applied for visual detection of multiple nucleic acids in a single, test that is easy to operate. In this approach, a capillary array was used for multiplex and highly efficient detection of GMO targets.

毛细管阵列中多核酸的视觉检测

Multi-target, short time, and resource-affordable methodologies for the detection of multiple nucleic acids in a single, easy to operate test are urgently ...

Fabrication of a Multiplexed Artificial Cellular MicroEnvironment Array

Cellular microenvironments consist of a variety of cues, such as growth factors, extracellular matrices, and intercellular interactions. These cues are well orchestrated and are crucial in regulating cell functions in a living system. Although a number of researchers have attempted to investigate the correlation between environmental factors and desired cellular functions, much remains unknown. This is largely due to the lack of a proper methodology to mimic such environmental cues in vitro, and simultaneously test different environmental cues on cells. Here, we report an integrated platform of microfluidic channels and a nanofiber array, followed by high-content single-cell analysis, to examine stem cell phenotypes altered by distinct environmental factors. To demonstrate the application of this platform, this study focuses on the phenotypes of self-renewing human pluripotent stem cells (hPSCs). Here, we present the preparation procedures for a nanofiber array and the microfluidic structure in the fabrication of a Multiplexed Artificial Cellular MicroEnvironment (MACME) array. Moreover, overall steps of the single-cell profiling, cell staining with multiple fluorescent markers, multiple fluorescence imaging, and statistical analyses, are described.

This article describes the detailed methodology to prepare a Multiplexed Artificial Cellular MicroEnvironment (MACME) array for high-throughput manipulation of physical and chemical cues mimicking in vivo cellular microenvironments and to identify the optimal cellular environment for human pluripotent stem cells (hPSCs) with single-cell profiling.

多路人工细胞微环境阵列的制备

Cellular microenvironments consist of a variety of cues, such as growth factors, extracellular matrices, and intercellular interactions. These cues are ...