This work was supported by grants from the National Institutes of Health, including a microphysiological systems consortium grant from the National Center for Advancing Translational Sciences (UH2TR000503), a Ruth L. Kirschstein National Research Service Award Postdoctoral Fellowship (F32DK098905 for WJM) and pathway to independence award (DK095984 for AB) from the National Institute of Diabetes and Digestive and Kidney Diseases.

Yerli Çözünür Kolajen Çözüm 1. Hazırlık <ol><li> Hazırlama ya da 1-3 mg / örneğin Piez ve arkadaşları tarafından rapor edildiği gibi standart ayırma protokollerini kullanarak ml. 15 de sıçan kuyrukları kolajen asitleştirildi çözünür, tip 200 mg satın </li><li> Modifiye edilen kollajen çözeltilerinin istenen son hacmine bağlı olarak, başlangıç ​​malzemesinin miktarını Scale. Yaklaşık çözünebilir doğal kolajen 200 mg, 3 mg / ml metile edilmiş 25-30 ml ve süksinillenmiş kolajen çözeltilerinin 25-30 ml her biri tercih. </li></ol> 2. Kolajen Metilasyon <ol><li> Buz soğukluğunda steril su ile mi, 0.5 mg / lik bir konsantrasyon yerli asitlendirildi (pH 2-3), kolajen çözeltisi, 100 mg seyreltilir ve jelleşmesini önlemek için buz üzerinde çözüm tutmak. </li><li> 1 N NaOH ile birkaç damla 9-10 kolajen çözeltisinin pH değeri ayarlamak ve 30 dakika boyunca oda sıcaklığında karıştırıldı. Bulanık olma çözüm neden kollajen çökelti gözlemleyin. </li&gt; <li> 25 dakika boyunca 3000 x g&#39;de çöktürülmüş kollajen çözüm aşağı doğru döndürün. Berrak bir jel-benzeri çökelti tüplerin alt görünür olmalıdır. Aspire ve düzgün süpernatant sıvı atmayın. </li><li> 0.1 N HCI ile metanol içinde 200 ml çökelmiş kollajen yeniden süspanse edin ve metilasyon reaksiyonu 4 gün boyunca oda sıcaklığında karıştırma ile oluştuğu sağlar. Kollajen erimesi olmaz, ama çözüm bulutlu hale getirecek çok küçük görünür parçalar halinde parçalayın gerekir. </li><li> Metilasyon sonra santrifüj 25 dakika boyunca 3000 x g&#39;de çözüm metıle kollajen pelet. Aspire ve asitli metanol süpernatant atın. </li><li> Tekrar pipetleme ile yaklaşık 3 mg / ml&#39;lik bir konsantrasyona vererek, steril PBS 25 ml metile edilmiş kolajen çözündürülür ve bir 60 um&#39;lik bir hücre süzgecinden çözelti filtre edin. 1 N NaOH ile 20 ul artışlarını kullanarak 7.3-7.4 çözeltinin pH ayarlayın. </li><li> Concentratio değerlendirinticari bir sıçan kolajen ELISA kiti ya da hidroksiprolin tahlil kiti kullanılarak çözümün n. 3 mg / steril PBS ile ml çözeltisi ile seyreltilir. </li><li> Dikkatli bir şekilde şişenin altındaki kloroform 3 ml katman, bir vidalı başlık ile cam bir şişe aktararak metillenmiş kolajen çözeltisi sterilize, şişe, 4 ° C, O / N ayarlayın ve daha sonra aseptik olarak kaldırıp saklamak için izin metıle kollajen olan üst kat. </li><li> 1 ay içinde kullanım için 4 ° C&#39;da, çözelti saklayın. </li></ol> 3. Kolajen Succinylation <ol><li> Buz soğukluğunda steril su ile mi, 0.5 mg / lik bir konsantrasyon yerli asitlendirildi (pH 2-3), kolajen çözeltisi, diğer 100 mg seyreltilir ve jelleşmesini önlemek için buz üzerinde çözüm tutmak. </li><li> 1 N NaOH ile birkaç damla 9-10 kolajen çözeltisinin pH değeri ayarlamak ve 30 dakika boyunca oda sıcaklığında karıştırıldı. Kollajen bulanık olma çözüm neden çöktürmek gerekir. </li><li> Suc 40 mg çözülür(kolajen çözeltisinin hacmi inci 20/01) 10 ml aseton içinde cinic anhidrid (kolajen mg&#39;ı başına 0.4 mg) eklenir. Yavaş yavaş (yaklaşık 0.5 mi artışlarla) sürekli pH değerine karıştırılarak kolajen çözeltisi bu karışıma ekleyin. PH 9.0 yaklaşırken 1 N NaOH, 1 veya 2 damla eklenerek pH 9.0&#39;ın üzerinde muhafaza edin. </li><li> Aseton içinde süksinik anhidrit katan 120 dakika boyunca oda sıcaklığında karıştırmaya devam edin. Süksinillenmiş kollajen erir olarak açık hale çözüm gözlemleyin. Periyodik olarak 9.0 üstünde kalmasını sağlamak için pH değeri kontrol edin. </li><li> 1 N HCI 20 ul artışlarla 4.0 çözeltinin pH ayarlayın. Süksinillenmiş kollajen çökeltiler gibi yine bulutlu çözüm gözlemleyin. </li><li> Succinylation sonra santrifüj 25 dakika boyunca 3000 x g&#39;de çözüm süksinillenmiş kollajen pelet. Aspire ve reaksiyona girmemiş süksinik anhidrit ile asidifiye süpernatant atın. </li><li> Succinylated kolajen çözülürsteril PBS, 25 ml, 60 mikron hücre süzgecinden çözeltisi tekrar pipetle ml / yaklaşık 3 mg&#39;lık bir konsantrasyonunu vermek ve filtre bölgesi. 1 N NaOH ile 20 ul artışlarını kullanarak 7.3-7.4 çözeltinin pH ayarlayın. </li><li> Ticari bir kollajen sıçan ELISA kiti ya da hidroksiprolin tahlil kiti kullanılarak çözeltinin konsantrasyonunu değerlendirin. 3 mg / steril PBS ile ml çözeltisi ile seyreltilir. </li><li> Dikkatli bir şekilde şişenin altındaki kloroform 3 ml katman, bir vidalı başlık ile cam bir şişe aktararak süksinillenmiş kolajen çözeltisi sterilize, şişe, 4 ° C, O / N ayarlayın ve daha sonra aseptik olarak kaldırıp saklamak için izin süksinillenmiş kollajen olan üst kat. </li><li> 1 ay içinde kullanım için 4 ° C&#39;da, çözelti saklayın. </li></ol> Kollajen Değişiklikler 4. Doğrulama <ol><li> Doğal olarak metile edilmiş ve süksinillenmiş kollajen çözeltilerin her birinden 1 mi örnekleri hazırlayın ve konsantre seyreltinHidrojen iyonu titrasyon için steril saf su ile 0,1 mg / ml arasında entration. Bundan başka, en azından 4 saat için her 10 kDa kesme membraneusing 3 çözeltisi değişiklikler ile suya karşı diyaliz ile tampon, en az 1000 kat seyreltilir. </li><li> NaOH ve HCl az miktarda 7.3 çözeltilerin pH ayarlayın. Doğal olarak metile edilmiş ve süksinillenmiş kolajen çözeltileri için titrasyon eğrilerini oluşturmak için Tanford 16 tarafından tarif edildiği gibi rasgele bir referans olarak pH 7.3 kullanarak, örneğin her biri hidrojen iyon titrasyonu yapın. </li><li> Asit hacminin ilişkili H +, molekül başına elektron sayısına karşı eklenirler pH değişimine çizilir. Yüksek pH &quot;Amino&quot; sınıfı, nötr noktasına doğru süksinillenmiş kolajen bir kayma (amin gruplarının kaybı) göstermelidir ve düşük pH &quot;karboksil&quot; sınıfı için metile kollajen sola doğru bir kayma (karboksil gruplarının kaybı göstermelidir ) ve süksinillenmiş kollajen bir sağa kayışı (karboksil grubunda bir kazançs), doğal kolajen ile karşılaştırıldığında. </li><li> Standart protokoller 17,18 takiben, 2,4,6-trinitrobenzen sülfonik asit (TNBA) kolorimetrik yöntem kullanılarak succinylation ile ikame nativ kollajen amino gruplarının% belirleyerek succinylation reaksiyonunun etkinliğini değerlendirmek. </li></ol> Mikroakışkan Cihazlar ve Hücre Yayımlamak 5. Fabrikasyon <ol><li> Standart yöntemler kullanılarak 9 mikroakışkan cihazları imal. 100 mikron boyunda 0,4-1,5 mm genişliğinde ve hücre büyümesi için uzun kanallar 1-10 mm mikroakışkan hücre kültürü oda oluşturmak için fotolitografi kullanarak tanımlanan silikon üzerinde SU-8 ustaları PDMS çoğaltma kalıp kullanın. </li><li> Cihaz ve bir bardak slayt yüzeyini okside plazma temizleyici kullanın ve sonra bağ birlikte basın. En az 30 dakika boyunca UV ışığına maruz bırakılarak sterilize aygıtı sonra steril PBS içinde 50 ug / ml fibronektin bölmeyi doldurup, 45 dakika boyunca 37 ° C&#39;de inkübe edin. </li&gt; <li> Fenotipinde veya farklılaşma hali stabilizasyonu için kolajen jel gerektiren primer sıçan ya da insan hepatositleri gibi hücreler, cihazı Tohum. Bu cihaz başına 14 x 10 6 hücre / ml&#39;de tohumlanmıştır taze izole edilmiş fare primer hepatositlerinde 7,19 ya da ticari olarak temin edilebilir dondurulan primer insan hepatositleri 20 ul kullanımı. </li><li> Hücreler 4-6 saat takmak ve ardından serbest hücrelerin yıkayın ve büyüme ortamı ile kaplama medya yerine izin verin. Yayılma, tam hücre sağlamak ve hücrelerin konfluent tek tabaka oluşturmak için O / N inkübe edin. </li></ol> 6. katman-katman, bir kollajen depolanmasının <ol><li> Laminer akış, doku kültürü kaputu, cihaz başına her çözeltinin 10 uygulamalar için metil ve süksinillenmiş kolajen çözeltileri, yeterli miktarda, yanı sıra ortam birkaç ml hazırlar. Buz üzerinde çözüm tutun. Biz cihaz başına katmanın başına kollajen 20 ul (10-15 kat, toplam cihaz hacmi) kullanın. </li><li> Olmakmetilatlanmış (Polikatyonik) çözümü ile çırçır, daha sonra 20 metillenmiş bir ul ve sahip cihazlar yıkama alternatif her uygulama arasında 1 dakika bekledikten kolajen çözümleri succinylated. Aygıtı yaklaşık 20 dakika sürer solüsyon başına 10 kez, toplam yıkayın. Hücreler medya olmadan süreyi en aza indirmek için hızlı bir şekilde çalışın. </li><li> Yavaş yavaş büyüklüğüne bağlı olarak giriş / çıkışında biriken kollajen gözlemleyin. Sıvı Akış arttıkça direnci, medya ile bir veya iki kez aygıtı yıkayın ve sonra katmanlarını devam edin. </li><li> Tüm katmanları uygulandıktan sonra, taze medya ile iki kez cihazı durulayın ve inkübatör dönmek. Hücre tipine bağlı olarak, hepatositler geliştirilmiş polarizasyon gibi hücre dışı matris ile indüklenen morfolojik değişiklikler, bir kaç saat içinde görünür olmalıdır. </li><li> Kollajen matrisin mevcudiyetini doğrulamak için standart yöntemler kullanılarak 9 transmisyon elektron mikroskopisi için temsili cihazlar hazırlayınkültürlenmiş hücrelerin üzerine montajı. </li></ol> Hücre Fenotip ve Fonksiyon 7. Stabilizasyon <ol><li> Resim hücre tipi için standart yöntemler kullanılarak hücre morfolojisi, canlılık ve polaritesi. Hepatositlerde için, kollajen birikimi etkilerini göstermek için apikal polarizasyon faz mikroskobu, canlılığı için LIVE / DEAD boyama ve CMFDA boya kullanılarak 14 gün boyunca görüntüleri toplamak. </li><li> Hücre morfolojisi için, durulama, 20 ul PBS ve görüntüyü faz kontrast mikroskopisi kullanılarak cihazı enjekte PBS 20 ul ile pipetle giriş boyunca cihazı yıkayın. </li><li> Ölü / canlı boyama için, durulama, üretici talimatlarına göre hazırlanır DAPI ile ölü / canlı boyama çözeltisi 20 ul enjekte etmek için PBS 20 ul ile pipetle giriş boyunca aygıtı temizleme, 37 ° C&#39;de 30 dakika inkübe edilir, durulama Cihaz tekrar 20 PBS ul ve görüntünün floresan mikroskobu kullanarak cihazı ile. </li><li> Safra Canaliculi boyama, imalatçının talimatları izlenerek, 37 ° C de 30 dakika inkübe hazırlanan DAPI ile 2 uM CMFDA boyama çözeltisi 20 ul enjekte etmek için durulama PBS 20 ul ile pipetle giriş boyunca aygıtı temizleme ile tekrar cihazı yıkayın 20 ul PBS ve görüntü floresan mikroskobu kullanarak cihazı. </li><li> Harcanan ortam toplamak ve hücre fonksiyonunu belirlemek için, kültür süresi boyunca uygun zaman noktalarında hücresel metabolik ürünlerini ölçmek. Hepatositler için, harcanan ortam içinde albumin ve üre miktarını ölçer. </li><li> Böyle değerlendirmek enzim aktivite düzeyleri, antikor boyama ya da RNA analiz gibi hücreler kendilerini, üzerinde son nokta fonksiyonel analizler gerçekleştirin. Hepatositlerde için, neden ve sitokrom P450 enzim faaliyetleri veya faz II konjugasyon enzim glutatyon S-transferaz ölçün. </li></ol>

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The authors have nothing to disclose.

Ultra ince saf kolajen düzenekleri değiştirilmiş kolajenlerin katman-katman birikimi ile şarj hücreleri veya malzeme yüzeylerinde yatırılabilir. Bu çalışmanın sonuçları, metilasyon ve yerli kolajen succinylation hücreleri (Şekil 2) ile ilgili ultra ince kollajen matris, derlemeleri yatırmak için katman-katman tekniği kullanılabilir (Şekil 1) ve diğer yüklü polikatyonik ve polianyonik kolajen çözümleri oluşturmak göstermektedir Malzeme yüzeyler. Böyle ultr...

Although microfluidics allows for the exquisite control of the cellular microenvironment, culturing cells, especially primary cells, within microfluidic devices can be challenging. Many traditional cell culture techniques have been developed to sustain and stabilize cell function when cultured in tissue culture plates, but translating those techniques to microfluidic devices is often difficult. 
One such technique is the culture of cells on or sandwiched between collagen gels as a model of the physiological 3D cell environment.1 Type I collagen is one of the most frequently used proteins for biomaterials applications because of its ubiquity in extracellular matrix, natural abundance, robust cell attachment sites, and biocompatibility.2 Many cells benefit from 3D culture with collagen, including cancer cells3,45, microvascular endothelial cells6, and hepatocytes7, among others. While the use of collagen gels is easy in open formats, such as tissue culture plates, the limited channel dimensions and enclosed nature of microfluidic devices makes the use of liquids that gel impractical without blocking the entire channel.
To overcome this problem, we combined the layer-by-layer deposition technique8 with chemical modifications of native collagen solutions to create ultrathin collagen assemblies on top of cells cultured in microfluidic devices. These layers can stabilize cell morphology and function similar to collagen gels and can be deposited on cells in microfluidic devices without blocking the channels with polymerized matrix. The goal of this method is to modify native collagen to create polycationic and polyanionic collagen solutions and to stabilize cells in microfluidic culture by depositing thin collagen matrix assemblies onto the cells. This technique has been used to stabilize the morphology and function of primary hepatocytes in microfluidic devices.9
Although layer-by-layer deposition has previously been reported with natural and synthetic polyelectrolytes10 to cover hepatocytes in plate culture11,12 and as a seeding layer for hepatocytes in microfluidic devices13,14, this method describes the deposition of a pure collagen layer on top of hepatocytes, mimicking the 3D collagen culture techniques. In this protocol, we use hepatocytes as example cells that can be maintained using 3D collagen layers. The many other types of cells that benefit from 3D culture in collagen may similarly benefit from culture after layer-by-layer deposition of an ultrathin collagen matrix assembly.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>collagen type I, rat tail</td>
			<td>Life Technologies</td>
			<td>A1048301</td>
			<td>option for concentrated rat tail collagen</td>
		</tr>
		<tr>
			<td>collagen type I, rat tail</td>
			<td>Sigma-Aldrich</td>
			<td>C3867-1VL</td>
			<td>option for concentrated rat tail collagen</td>
		</tr>
		<tr>
			<td>collagen type I, rat tail</td>
			<td>EMD Millipore</td>
			<td>08-115</td>
			<td>option for concentrated rat tail collagen</td>
		</tr>
		<tr>
			<td>collagen type I, rat tail</td>
			<td>R%D Systems</td>
			<td>3440-100-01</td>
			<td>option for concentrated rat tail collagen</td>
		</tr>
		<tr>
			<td>succinic anhydride</td>
			<td>Sigma-Aldrich</td>
			<td>239690-50G</td>
			<td>succinylation reagent</td>
		</tr>
		<tr>
			<td>anhydrous methanol</td>
			<td>Sigma-Aldrich</td>
			<td>322415-100ML</td>
			<td>methylation reagent</td>
		</tr>
		<tr>
			<td>sodium hydroxide</td>
			<td>Sigma-Aldrich</td>
			<td>S5881-500G</td>
			<td>pH precipitation reagent</td>
		</tr>
		<tr>
			<td>hydrochloric acid</td>
			<td>Sigma-Aldrich</td>
			<td>320331-500ML</td>
			<td>pH precipitation reagent</td>
		</tr>
		<tr>
			<td>rat collagen type I ELISA</td>
			<td>Chondrex</td>
			<td>6013</td>
			<td>option for detecting collagen content</td>
		</tr>
		<tr>
			<td>hydroxyproline assay kit</td>
			<td>Sigma-Aldrich</td>
			<td>MAK008-1KT</td>
			<td>option for detecting collagen content</td>
		</tr>
		<tr>
			<td>hydroxyproline assay kit</td>
			<td>Quickzyme Biosciences</td>
			<td>QZBtotcol1</td>
			<td>option for detecting collagen content</td>
		</tr>
	</tbody>
</table>

layer-by-layer collagen deposition in microfluidic devices for microtissue stabilization

Although microfluidics provides exquisite control of the cellular microenvironment, culturing cells within microfluidic devices can be challenging. 3D culture of cells in collagen type I gels helps to stabilize cell morphology and function, which is necessary for creating microfluidic tissue models in microdevices. Translating traditional 3D culture techniques for tissue culture plates to microfluidic devices is often difficult because of the limited channel dimensions. In this method, we describe a technique for modifying native type I collagen to generate polycationic and polyanionic collagen solutions that can be used with layer-by-layer deposition to create ultrathin collagen assemblies on top of cells cultured in microfluidic devices. These thin collagen layers stabilize cell morphology and function, as shown using primary hepatocytes as an example cell, allowing for the long term culture of microtissues in microfluidic devices.

Yerli kollajen tabakası-katman birikimi kullanmak için polikatyonik ve polianyonik kollajen çözümleri oluşturmak için metilasyon ve succinylation kullanılarak değiştirilebilir. Succinylation sukkinil grupları ile nativ kollajen ε-amino grupları değiştirir ve metilasyon, bir metil grubu (Şekil 1A) ile saf kollajenine karboksil gruplarını değiştirir. Kollajen proteini amino asit yan zincirlerine Bu modifikasyonlar çözeltiler pH titrasyon eğrilerini değiştirebilir. Metilasyon, amin...

Watch this Scientific Journal Video about Layer-by-layer Collagen Deposition in Microfluidic Devices for Microtissue Stabilization at JoVE.com

Layer-by-layer Collagen Deposition in Microfluidic Devices for Microtissue Stabilization

The creation of functional microtissues within microfluidic devices requires the stabilization of cell phenotypes by adapting traditional cell culture techniques to the limited spatial dimensions in microdevices. Modification of collagen allows the layer-by-layer deposition of ultrathin collagen assemblies that can stabilize primary cells, such as hepatocytes, as microfluidic tissue models.

Microtissue Sabitleme için mikroakışkan Cihazlar Katman-katman Kolajen Biriktirme

Although microfluidics provides exquisite control of the cellular microenvironment, culturing cells within microfluidic devices can be challenging. 3D ...

layer-layer-collagen-deposition-microfluidic-devices-for-microtissue

Research

JoVE Journal

Bioengineering

9.3K Görüntüleme.  Massachusetts General Hospital, Harvard Medical School. The creation of functional microtissues within microfluidic devices requires the stabilization of cell phenotypes by adapting traditional cell culture techniques to the limited spatial dimensions in microdevices. Modification of collagen allows the layer-by-layer deposition of ultrathin collagen assemblies that can stabilize primary cells, such as hepatocytes, as microfluidic tissue models.

Video: Layer-by-layer Collagen Deposition in Microfluidic Devices for Microtissue Stabilization

Separating Beads and Cells in Multi-channel Microfluidic Devices Using Dielectrophoresis and Laminar Flow

Microfluidic devices have advanced cell studies by providing a dynamic fluidic environment on the scale of the cell for studying, manipulating, sorting and counting cells. However, manipulating the cell within the fluidic domain remains a challenge and requires complicated fabrication protocols for forming valves and electrodes, or demands specialty equipment like optical tweezers. Here, we demonstrate that conventional printed circuit boards (PCB) can be used for the non-contact manipulation of cells by employing dielectrophoresis (DEP) for bead and cell manipulation in laminar flow fields for bioactuation, and for cell and bead separation in multichannel microfluidic devices. First, we present the protocol for assembling the DEP electrodes and microfluidic devices, and preparing the cells for DEP. Then, we characterize the DEP operation with polystyrene beads. Lastly, we show representative results of bead and cell separation in a multichannel microfluidic device. In summary, DEP is an effective method for manipulating particles (beads or cells) within microfluidic devices.

Dielectrophoresis (DEP) is an effective method to manipulate cells. Printed circuit boards (PCB) can provide inexpensive, reusable and effective electrodes for contact-free cell manipulation within microfluidic devices. By combining PDMS-based microfluidic channels with coverslips on PCBs, we demonstrate bead and cell manipulation and separation within multichannel microfluidic devices.

Çok kanallı mikroakışkan Cihazlar ayırmak Boncuk ve Hücreler Dielectrophoresis ve Laminar Flow

Microfluidic devices have advanced cell studies by providing a dynamic fluidic environment on the scale of the cell for studying, manipulating, sorting ...

Biyomühendislik

Simple Microfluidic Devices for in vivo Imaging of C. elegans, Drosophila and Zebrafish

Micro fabricated fluidic devices provide an accessible micro-environment for in vivo studies on small organisms. Simple fabrication processes are available for microfluidic devices using soft lithography techniques 1-3. Microfluidic devices have been used for sub-cellular imaging 4,5, in vivo laser microsurgery 2,6 and cellular imaging 4,7. In vivo imaging requires immobilization of organisms. This has been achieved using suction 5,8, tapered channels 6,7,9, deformable membranes 2-4,10, suction with additional cooling 5, anesthetic gas 11, temperature sensitive gels 12, cyanoacrylate glue 13 and anesthetics such as levamisole 14,15. Commonly used anesthetics influence synaptic transmission 16,17 and are known to have detrimental effects on sub-cellular neuronal transport 4. In this study we demonstrate a membrane based poly-dimethyl-siloxane (PDMS) device that allows anesthetic free immobilization of intact genetic model organisms such as Caenorhabditis elegans (C. elegans), Drosophila larvae and zebrafish larvae. These model organisms are suitable for in vivo studies in microfluidic devices because of their small diameters and optically transparent or translucent bodies. Body diameters range from ~10 &mu;m to ~800 &mu;m for early larval stages of C. elegans and zebrafish larvae and require microfluidic devices of different sizes to achieve complete immobilization for high resolution time-lapse imaging. These organisms are immobilized using pressure applied by compressed nitrogen gas through a liquid column and imaged using an inverted microscope. Animals released from the trap return to normal locomotion within 10 min.
We demonstrate four applications of time-lapse imaging in C. elegans namely, imaging mitochondrial transport in neurons, pre-synaptic vesicle transport in a transport-defective mutant, glutamate receptor transport and Q neuroblast cell division. Data obtained from such movies show that microfluidic immobilization is a useful and accurate means of acquiring in vivo data of cellular and sub-cellular events when compared to anesthetized animals (Figure 1J and 3C-F 4).
Device dimensions were altered to allow time-lapse imaging of different stages of C. elegans, first instar Drosophila larvae and zebrafish larvae. Transport of vesicles marked with synaptotagmin tagged with GFP (syt.eGFP) in sensory neurons shows directed motion of synaptic vesicle markers expressed in cholinergic sensory neurons in intact first instar Drosophila larvae. A similar device has been used to carry out time-lapse imaging of heartbeat in ~30 hr post fertilization (hpf) zebrafish larvae. These data show that the simple devices we have developed can be applied to a variety of model systems to study several cell biological and developmental phenomena in vivo.

Simple Microfluidic Devices for in vivo Imaging of C. elegans, Drosophila and Zebrafish

A simple microfluidic device has been developed to perform anesthetic free in vivo imaging of C. elegans, intact Drosophila larvae and zebrafish larvae. The device utilizes a deformable PDMS membrane to immobilize these model organisms in order to perform time lapse imaging of numerous processes such as heart beat, cell division and sub-cellular neuronal transport. We demonstrate the use of this device and show examples of different types of data collected from different model systems.

Için basit Mikroakışkan Cihazlar<em&gt; In vivo</emVe&gt; Görüntüleme<em&gt; C. elegans</em&gt;,<em&gt; Drosophila</em&gt; Ve Zebra balığı

Micro fabricated fluidic devices provide an accessible micro-environment for in vivo studies on small organisms. Simple fabrication processes are ...

Engineering 3D Cellularized Collagen Gels for Vascular Tissue Regeneration

Synthetic materials are known to initiate clinical complications such as inflammation, stenosis, and infections when implanted as vascular substitutes. Collagen has been extensively used for a wide range of biomedical applications and is considered a valid alternative to synthetic materials due to its inherent biocompatibility (i.e., low antigenicity, inflammation, and cytotoxic responses). However, the limited mechanical properties and the related low hand-ability of collagen gels have hampered their use as scaffold materials for vascular tissue engineering. Therefore, the rationale behind this work was first to engineer cellularized collagen gels into a tubular-shaped geometry and second to enhance smooth muscle cells driven reorganization of collagen matrix to obtain tissues stiff enough to be handled.
The strategy described here is based on the direct assembling of collagen and smooth muscle cells (construct) in a 3D cylindrical geometry with the use of a molding technique. This process requires a maturation period, during which the constructs are cultured in a bioreactor under static conditions (without applied external dynamic mechanical constraints) for 1 or 2 weeks. The &#8220;static bioreactor&#8221; provides a monitored and controlled sterile environment (pH, temperature, gas exchange, nutrient supply and waste removal) to the constructs. During culture period, thickness measurements were performed to evaluate the cells-driven remodeling of the collagen matrix, and glucose consumption and lactate production rates were measured to monitor the cells metabolic activity. Finally, mechanical and viscoelastic properties were assessed for the resulting tubular constructs. To this end, specific protocols and a focused know-how (manipulation, gripping, working in hydrated environment, and so on) were developed to characterize the engineered tissues.

In this work, we present a technique for the rapid fabrication of living vascular tissues by direct culturing of collagen, smooth muscle cells and endothelial cells. In addition, a new protocol for the mechanical characterization of engineered vascular tissues is described.

Vasküler Doku Rejenerasyon için Mühendislik 3D cellularized Kollajen jeller

Synthetic materials are known to initiate clinical complications such as inflammation, stenosis, and infections when implanted as vascular substitutes. ...

Microfluidic Genipin Deposition Technique for Extended Culture of Micropatterned Vascular Muscular Thin Films

The chronic nature of vascular disease progression requires the development of experimental techniques that simulate physiologic and pathologic vascular behaviors on disease-relevant time scales. Previously, microcontact printing has been used to fabricate two-dimensional functional arterial mimics through patterning of extracellular matrix protein as guidance cues for tissue organization. Vascular muscular thin films utilized these mimics to assess functional contractility. However, the microcontact printing fabrication technique used typically incorporates hydrophobic PDMS substrates. As the tissue turns over the underlying extracellular matrix, new proteins must undergo a conformational change or denaturing in order to expose hydrophobic amino acid residues to the hydrophobic PDMS surfaces for attachment, resulting in altered matrix protein bioactivity, delamination, and death of the tissues.
Here, we present a microfluidic deposition technique for patterning of the crosslinker compound genipin. Genipin serves as an intermediary between patterned tissues and PDMS substrates, allowing cells to deposit newly-synthesized extracellular matrix protein onto a more hydrophilic surface and remain attached to the PDMS substrates. We also show that extracellular matrix proteins can be patterned directly onto deposited genipin, allowing dictation of engineered tissue structure. Tissues fabricated with this technique show high fidelity in both structural alignment and contractile function of vascular smooth muscle tissue in a vascular muscular thin film model. This technique can be extended using other cell types and provides the framework for future study of chronic tissue- and organ-level functionality.

We present a method for microfluidic deposition of patterned genipin and fibronectin on PDMS substrates, allowing extended viability of vascular smooth muscle cell-dense tissues. This tissue fabrication method is combined with previous vascular muscular thin film technology to measure vascular contractility over disease-relevant time courses.

Micropatterned Vasküler Musküler İnce Filmlerin Genişletilmiş Kültür mikroakışkan Genipin Biriktirme Tekniği

The chronic nature of vascular disease progression requires the development of experimental techniques that simulate physiologic and pathologic vascular ...

Using Adhesive Patterning to Construct 3D Paper Microfluidic Devices

We demonstrate the use of patterned aerosol adhesives to construct both planar and nonplanar 3D paper microfluidic devices. By spraying an aerosol adhesive through a metal stencil, the overall amount of adhesive used in assembling paper microfluidic devices can be significantly reduced. We show on a simple 4-layer planar paper microfluidic device that the optimal adhesive application technique and device construction style depends heavily on desired performance characteristics. By moderately increasing the overall area of a device, it is possible to dramatically decrease the wicking time and increase device success rates while also reducing the amount of adhesive required to keep the device together. Such adhesive application also causes the adhesive to form semi-permanent bonds instead of permanent bonds between paper layers, enabling single-use devices to be non-destructively disassembled after use. Nonplanar 3D origami devices also benefit from the semi-permanent bonds during folding, as it reduces the likelihood that unrelated faces may accidently stick together. Like planar devices, nonplanar structures see reduced wicking times with patterned adhesive application vs uniformly applied adhesive.

We demonstrate the use of patterned aerosol adhesives to construct 3D paper microfluidic devices. This method of adhesive application forms semi-permanent bonds between layers, enabling single-use devices to be non-destructively disassembled after use and to ease folding complex nonplanar structures.

3D Kağıt mikroakışkan Cihazlar Construct Yapışkan Desenlendirme kullanma

We demonstrate the use of patterned aerosol adhesives to construct both planar and nonplanar 3D paper microfluidic devices. By spraying an aerosol ...

Designing Microfluidic Devices for Studying Cellular Responses Under Single or Coexisting Chemical/Electrical/Shear Stress Stimuli

Microfluidic devices are capable of creating a precise and controllable cellular micro-environment of pH, temperature, salt concentration, and other physical or chemical stimuli. They have been commonly used for in vitro cell studies by providing in vivo like surroundings. Especially, how cells response to chemical gradients, electrical fields, and shear stresses has drawn many interests since these phenomena are important in understanding cellular properties and functions. These microfluidic chips can be made of glass substrates, silicon wafers, polydimethylsiloxane (PDMS) polymers, polymethylmethacrylate (PMMA) substrates, or polyethyleneterephthalate (PET) substrates. Out of these materials, PMMA substrates are cheap and can be easily processed using laser ablation and writing. Although a few microfluidic devices have been designed and fabricated for generating multiple, coexisting chemical and electrical stimuli, none of them was considered efficient enough in reducing experimental repeats, particular for screening purposes. In this report, we describe our design and fabrication of two PMMA-based microfluidic chips for investigating cellular responses, in the production of reactive oxygen species and the migration, under single or coexisting chemical/electrical/shear stress stimuli. The first chip generates five relative concentrations of 0, 1/8, 1/2, 7/8, and 1 in the culture regions, together with a shear stress gradient produced inside each of these areas. The second chip generates the same relative concentrations, but with five different electric field strengths created within each culture area. These devices not only provide cells with a precise, controllable micro-environment but also greatly increase the experimental throughput.

Micro-fabricated devices integrated with fluidic components provide an in vitro platform for cell studies mimicking the in vivo micro-environment. We developed polymethylmethacrylate-based microfluidic chips for studying cellular responses under single or coexisting chemical/electrical/shear stress stimuli.

Tek ya da Eşlik Kimya / Elektrik / Kesme Stres Uyaranların altında Hücresel Yanıtları incelenmesi için mikroakışkan Cihazlar Tasarımı

Microfluidic devices are capable of creating a precise and controllable cellular micro-environment of pH, temperature, salt concentration, and other ...

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.

Ventilli Katmanlı mikroakışkan Cihazlar için çok adımlı Değişken Yükseklik Fotolitografi

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

Fabrication of Three-dimensional Paper-based Microfluidic Devices for Immunoassays

Paper wicks fluids autonomously due to capillary action. By patterning paper with hydrophobic barriers, the transport of fluids can be controlled and directed within a layer of paper. Moreover, stacking multiple layers of patterned paper creates sophisticated three-dimensional microfluidic networks that can support the development of analytical and bioanalytical assays. Paper-based microfluidic devices are inexpensive, portable, easy to use, and require no external equipment to operate. As a result, they hold great promise as a platform for point-of-care diagnostics. In order to properly evaluate the utility and analytical performance of paper-based devices, suitable methods must be developed to ensure their manufacture is reproducible and at a scale that is appropriate for laboratory settings. In this manuscript, a method to fabricate a general device architecture that can be used for paper-based immunoassays is described. We use a form of additive manufacturing (multi-layer lamination) to prepare devices that comprise multiple layers of patterned paper and patterned adhesive. In addition to demonstrating the proper use of these three-dimensional paper-based microfluidic devices with an immunoassay for human chorionic gonadotropin (hCG), errors in the manufacturing process that may result in device failures are discussed. We expect this approach to manufacturing paper-based devices will find broad utility in the development of analytical applications designed specifically for limited-resource settings.

We detail a method to fabricate three-dimensional paper-based microfluidic devices for use in the development of immunoassays. Our approach to device assembly is a type of multilayer, additive manufacturing. We demonstrate a sandwich immunoassay to provide representative results for these types of paper-based devices.

İmmüno için üç boyutlu Paper-based mikroakışkan Cihazlar İmalat

Paper wicks fluids autonomously due to capillary action. By patterning paper with hydrophobic barriers, the transport of fluids can be controlled and ...

Polydimethylsiloxane-polycarbonate Microfluidic Devices for Cell Migration Studies Under Perpendicular Chemical and Oxygen Gradients

This paper reports a microfluidic device made of polydimethylsiloxane (PDMS) with an embedded polycarbonate (PC) thin film to study cell migration under combinations of chemical and oxygen gradients. Both chemical and oxygen gradients can greatly affect cell migration in vivo; however, due to technical limitations, very little research has been performed to investigate their effects in vitro. The device developed in this research takes advantage of a series of serpentine-shaped channels to generate the desired chemical gradients and exploits a spatially confined chemical reaction method for oxygen gradient generation. The directions of the chemical and oxygen gradients are perpendicular to each other to enable straightforward migration result interpretation. In order to efficiently generate the oxygen gradients with minimal chemical consumption, the embedded PC thin film is utilized as a gas diffusion barrier. The developed microfluidic device can be actuated by syringe pumps and placed into a conventional cell incubator during cell migration experiments to allow for setup simplification and optimized cell culture conditions. In cell experiments, we used the device to study migrations of adenocarcinomic human alveolar basal epithelial cells, A549, under combinations of chemokine (stromal cell-derived factor, SDF-1&#945;) and oxygen gradients. The experimental results show that the device can stably generate perpendicular chemokine and oxygen gradients and is compatible with cells. The migration study results indicate that oxygen gradients may play an essential role in guiding cell migration, and cellular behavior under combinations of gradients cannot be predicted from those under single gradients. The device provides a powerful and practical tool for researchers to study interactions between chemical and oxygen gradients in cell culture, which can promote better cell migration studies in more in vivo-like microenvironments.

The control of chemical and oxygen gradients is essential for cell cultures. This paper reports a polydimethylsiloxane-polycarbonate (PDMS-PC) microfluidic device capable of reliably generating combinations of chemical and oxygen gradients for cell migration studies, which can be practically utilized in biological labs without sophisticated instrumentation.

Hücre Göç Çalışmaları altında Dik Kimya ve Oksijen Gradyanların için polidimetilsiloksan-polikarbonat mikroakışkan Cihazlar

This paper reports a microfluidic device made of polydimethylsiloxane (PDMS) with an embedded polycarbonate (PC) thin film to study cell migration under ...

A Microfluidic Flow Chamber Model for Platelet Transfusion and Hemostasis Measures Platelet Deposition and Fibrin Formation in Real-time

Microfluidic models of hemostasis assess platelet function under conditions of hydrodynamic shear, but in the presence of anticoagulants, this analysis is restricted to platelet deposition only. The intricate relationship between Ca2+-dependent coagulation and platelet function requires careful and controlled recalcification of blood prior to analysis. Our setup uses a Y-shaped mixing channel, which supplies concentrated Ca2+/Mg2+ buffer to flowing blood just prior to perfusion, enabling rapid recalcification without sample stasis. A ten-fold difference in flow velocity between both reservoirs minimizes dilution. The recalcified blood is then perfused in a collagen-coated analysis chamber, and differential labeling permits real-time imaging of both platelet and fibrin deposition using fluorescence video microscopy. The system uses only commercially available tools, increasing the chances of standardization. Reconstitution of thrombocytopenic blood with platelets from banked concentrates furthermore models platelet transfusion, proving its use in this research domain. Exemplary data demonstrated that coagulation onset and fibrin deposition were linearly dependent on the platelet concentration, confirming the relationship between primary and secondary hemostasis in our model. In a timeframe of 16 perfusion min, contact activation did not take place, despite recalcification to normal Ca2+ and Mg2+ levels. When coagulation factor XIIa was inhibited by corn trypsin inhibitor, this time frame was even longer, indicating a considerable dynamic range in which the changes in the procoagulant nature of the platelets can be assessed. Co-immobilization of tissue factor with collagen significantly reduced the time to onset of coagulation, but not its rate. The option to study the tissue factor and/or the contact pathway increases the versatility and utility of the assay.

This paper describes an experimental model of hemostasis that simultaneously measures platelet function and coagulation. Platelet and fibrin fluorescence is measured in real-time, and platelet adhesion rate, coagulation rate, and onset of coagulation are determined. The model is used to determine platelet procoagulant properties under flow in concentrates for transfusion.

Trombosit Transfüzyon ve Hemostaz için bir mikroakışkan Akış Odası Modeli Gerçek zamanlı Trombosit Birikimi ve Fibrin oluşumu Tedbirleri

Microfluidic models of hemostasis assess platelet function under conditions of hydrodynamic shear, but in the presence of anticoagulants, this analysis is ...