Name: fabrication of three-dimensional paper-based microfluidic devices for immunoassays
Uploaded: 2017-03-09T14:00:00
Description: Watch this Scientific Journal Video about Fabrication of Three-dimensional Paper-based Microfluidic Devices for Immunoassays at JoVE.com

This work was supported by Tufts University and by a generous gift from Dr. James Kanagy. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. (DGE-1325256) that was awarded to S.C.F. D.J.W. was supported by a U.S. Department of Education GAANN fellowship. We thank Dr. Jeremy Schonhorn (JanaCare), Dr. Jason Rolland (Carbon3D), and Rachel Deraney (Brown University) for helping develop the design of the three-dimensional paper-based microfluidic device and immunoassay.

1. Preparation of Paper-based Microfluidic Device Layers
<ol>
	<li>Prepare patterns for layers of paper, nylon, and adhesive using a graphic design software program.6 Each layer may have a different pattern. 
	NOTE: The pattern may include alignment holes that are not required for a functional paper-based immunoassay, but assist with the reproducible manufacture of three-dimensional devices. Placement of these holes will differ if devices are assembled individually, in strips, or as full sh...

<ol>
	<li>Martinez, A. W., Phillips, S. T., Wiley, B. J., Gupta, M., Whitesides, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FLASH:+A+rapid+method+for+prototyping+paper-based+microfluidic+devices.">FLASH: A rapid method for prototyping paper-based microfluidic devices.</a> Lab Chip. 8 (12), 2146-2150 (2008).</li><li>Carrilho, E., Martinez, A. W., Whitesides, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Understanding+wax+printing:+a+simple+micropatterning+process+for+paper-based+microfluidic+devices.">Understanding wax printing: a simple micropatterning process for paper-based microfluidic devices.</a> Anal. Chem. 81 (16), 7091-7095 (2009).</li><li>Martinez, A. W., Phillips, S. T., Butte, M. J., Whitesides, G. 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K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Microfluidic+paper-based+analytical+devices+(&#181;PADs)+and+micro+total+analysis+systems+(&#181;TAS):+Development,+applications+and+future+trends.">Microfluidic paper-based analytical devices (&#181;PADs) and micro total analysis systems (&#181;TAS): Development, applications and future trends.</a> Chromatographia. 76, 1201-1214 (2013).</li><li>Pollock, N. R., 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=A+paper-based+multiplexed+transaminase+test+for+low-cost,+point-of-care+liver+function+testing.">A paper-based multiplexed transaminase test for low-cost, point-of-care liver function testing.</a> Sci. Transl. Med. 4 (152), 152ra129 (2012).</li><li>Mentele, M. M., Cunningham, J., Koehler, K., Volckens, J., Henry, C. 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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=Measuring+markers+of+liver+function+using+a+micro-patterned+paper+device+designed+for+blood+from+a+fingerprick.">Measuring markers of liver function using a micro-patterned paper device designed for blood from a fingerprick.</a> Anal Chem. 84 (6), 2883-2891 (2012).</li><li>Nie, Z., Deiss, F., Liu, X., Akbulut, O., Whitesides, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integration+of+paper-based+microfluidic+devices+with+commercial+electrochemical+readers.">Integration of paper-based microfluidic devices with commercial electrochemical readers.</a> Lab Chip. 10 (22), 3163-3169 (2010).</li><li>Martinez, A. 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=Programmable+diagnostic+devices+made+from+paper+and+tape.">Programmable diagnostic devices made from paper and tape.</a> Lab Chip. 10 (19), 2499-2504 (2010).</li><li>Connelly, J. T., Rolland, J. P., Whitesides, G. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=&#34;Paper+machine&#34;+for+molecular+diagnostics.">&#34;Paper machine&#34; for molecular diagnostics.</a> Anal. Chem. 87 (15), 7595-7601 (2015).</li><li>Schonhorn, J. E., Fernandes, S. C., Rajaratnam, A., Deraney, R. N., Rolland, J. P., Mace, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+device+architecture+for+three-dimensional,+patterned+paper+immunoassays.">A device architecture for three-dimensional, patterned paper immunoassays.</a> Lab Chip. 14 (24), 4653-4658 (2014).</li><li>Fernandes, S. C., Logounov, G. S., Munro, J. B., Mace, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+three+indirect+immunoassay+formats+on+a+common+paper-based+microfluidic+device+architecture.">Comparison of three indirect immunoassay formats on a common paper-based microfluidic device architecture.</a> Anal. Methods. 8 (26), 5204-5211 (2016).</li><li>Deraney, R. N., Mace, C. R., Rolland, J. P., Multiplexed Schonhorn, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=patterned-paper+immunoassay+for+detection+of+malaria+and+dengue+fever.">patterned-paper immunoassay for detection of malaria and dengue fever.</a> Anal. Chem. 88 (12), 6161-6165 (2016).</li><li>Abramoff, M., Magalhaes, P. J., Ram, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Image+processing+with+ImageJ.">Image processing with ImageJ.</a> Biophotonics Int. 11 (7), 36-42 (2004).</li><li>Derda, R., 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=Multizone+paper+platform+for+3D+cell+cultures.">Multizone paper platform for 3D cell cultures.</a> PLoS ONE. 6 (5), e18940 (2011).</li><li>Mace, C. R., Deraney, R. 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Soc. 133 (44), 17564-17566 (2011).</li><li>Kalish, B., Tsutsui, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Using+Adhesive+patterning+to+construct+3D+paper+microfluidic+devices.">Using Adhesive patterning to construct 3D paper microfluidic devices.</a> J. Vis. Exp. (110), e53805 (2016).</li><li>Scida, K., Cunningham, J. C., Renault, C., Richards, I., Crooks, R. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Simple,+sensitive,+and+quantitative+electrochemical+detection+method+for+paper+analytical+devices.">Simple, sensitive, and quantitative electrochemical detection method for paper analytical devices.</a> Anal. Chem. 86 (13), 6501-6507 (2014).</li><li>Lewis, G. G., DiTucci, M. J., Baker, M. S., Phillips, S. 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Identifying a reproducible manufacturing strategy is an essential component of assay development.22 We use a sequential, layer-by-layer approach to manufacture three-dimensional paper-based microfluidic devices. In contrast to those methods that apply folding or origami techniques to produce multilayer devices from a single sheet of paper23,24 additive manufacturing offers a number of advantages: (i) Multiple materials can be incorporated ...

Paper is widely available in a range of formulations or grades, can be functionalized to tune its properties, and can transport fluids autonomously by capillary action or wicking. If paper is patterned with a hydrophobic substance (e.g., photoresist1 or wax2), the wicking of fluids can be controlled spatially within a layer of paper. For example, an applied aqueous sample can be directed into a number of different zones to react with chemical and biochemical reagents stored within the paper. These paper-based microfluidic devices have been demonstrated to be a useful platform for the development of portable and inexpensive analytical assays3,4,5,6,7. Applications of paper-based microfluidic devices include point-of-care diagnostics8, monitoring of environmental contaminants9, detection of counterfeit pharmaceuticals10, and delocalized healthcare (or &#34;telemedicine&#34;) in limited-resource settings11.
Multiple layers of patterned paper can be assembled into an integrated device where hydrophilic zones from neighboring layers (i.e., above or below) connect to form continuous fluidic networks whose inlets and outlets may be coupled or left independent.12 Each layer can comprise a unique pattern, which enables the spatial separation of reagents and multiple assays to be performed on a single device. The resulting three-dimensional microfluidic device is not only capable of wicking fluids to enable analytical assays (e.g., liver function tests13 and electrochemical detection of small molecules14), but it can also support a number of sophisticated functions (e.g., valves15 and simple machines16) common to traditional microfluidic approaches. Importantly, because paper wicks fluids by capillary action, these devices can be operated with minimal effort from the user.
Since reagents can be stored within the three-dimensional architecture of a paper-based device, complex protocols can be reduced to a single addition of aqueous sample to a device. Recently, we introduced a general three-dimensional device architecture that can be used for the development of paper-based immunoassays using the wax-printing technique to create patterned layers.17,18 These studies focused on how aspects related to the design of the device-number of stacked layers used, composition of the layers, and the pattern of the three-dimensional microfluidic network-controlled the overall performance of the immunoassay. Ultimately, we were able to use these design rules to facilitate the rapid development of a multiplexed immunoassay19. In this manuscript, a previously developed immunoassay for human chorionic gonadotropin (hCG; pregnancy hormone)17 is used as an example to illustrate the strategies that we have developed for the assembly and manufacture of three-dimensional paper-based immunoassays. Accordingly, we focus on the assembly and operation of a device rather than the development of an assay.
In a sandwich immunoassay, which is the format used to detect hCG, a capture antibody specific to one subunit of the hormone is coated onto a solid substrate, which is then blocked to limit the non-specific adsorption of a sample or any subsequent reagent. This substrate is most often a polystyrene microwell plate (e.g., for an enzyme-linked immunosorbent assay or ELISA). The sample is then added to a well and allowed to incubate for a period of time. After rigorous washing, an antibody specific to the other subunit of hCG is added and allowed to incubate. This detection antibody may be conjugated to a colloidal particle, enzyme, or fluorophore in order to produce a measurable signal. The well is again washed prior to interpreting the results of an assay (e.g., using a plate reader). While commercial kits rely on this time-consuming multistep process, all of these steps can be performed rapidly in paper-based microfluidic devices with minimal intervention to the user.
The device used for the hCG immunoassay comprises six active layers, which are, from top to bottom, used for sample addition, conjugate storage, incubation, capture, wash, and blot (Figure 1). The sample addition layer is made from qualitative filter paper. It facilitates the introduction of a liquid sample and protects the reagents in the conjugate layer from contamination from the environment or accidental contact by the user. The conjugate layer (qualitative filter paper) holds the color-producing reagent (e.g., colloidal gold-labeled antibody) for the immunoassay. The incubation layer (qualitative filter paper) allows the sample to travel laterally within the plane of the paper to promote binding of the analyte with reagents before reaching the next layer, the capture layer. The capture layer (nylon membrane) contains ligands specific for the analyte adsorbed to the material. After the assay is completed, this layer is revealed to enable visualization of the completed immunocomplex. The wash layer (qualitative filter paper) draws excess fluids including free conjugate reagents away from the face of the capture layer into the blot layer (thick chromatography paper). The six-layer device is held together by five layers of patterned, double-sided adhesive: four layers of permanent adhesive maintain the integrity of the assembled device and one layer of removable adhesive facilitates peeling of the device to inspect the results of the immunoassay on the capture layer.
For the purpose of this manuscript, we use only negative and positive control samples of hCG (0 mIU/mL and 81 mIU/mL, respectively) to provide representative results of a paper-based immunoassay, which permits a dedicated discussion of the relationship between fabrication methods and the performance of a device. In addition to demonstrating how to manufacture devices successfully, we highlight several manufacturing errors that could lead to the failure of a device or irreproducible assay results. The protocol and discussion detailed in this manuscript will provide researchers with valuable insight into how paper-based immunoassays are designed and fabricated. While we focus our demonstration on immunoassays, we anticipate that the guidelines presented herein will be broadly useful for the manufacture of three-dimensional paper-based microfluidic devices.

<table border="0" cellpadding="0" cellspacing="0" width="1059">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">Illustrator CC</td>
			<td style="width:135px;">Adobe</td>
			<td style="width:175px;"></td>
			<td style="width:304px;">to design patterns for layers of paper and adhesive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">Xerox ColorQube 8580 printer</td>
			<td style="width:135px;">Amazon</td>
			<td style="width:175px;">B00R92C9DI</td>
			<td>to print wax patterns onto layers of paper and Nylon</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">Isotemp General Purpose Heating and Drying Oven</td>
			<td style="width:135px;">Fisher Scientific</td>
			<td style="width:175px;">15-103-0509</td>
			<td>to melt wax into paper</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Artograph LightTracer</td>
			<td style="width:135px;">Amazon</td>
			<td style="width:175px;">B000KNHRH6</td>
			<td>to assist with alignment of layers</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">Apache AL13P laminator</td>
			<td style="width:135px;">Amazon</td>
			<td style="width:175px;">B00AXHSZU2</td>
			<td>to laminate layers together</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Graphtec CE6000 Cutting Plotter</td>
			<td style="width:135px;">Graphtec America</td>
			<td style="width:175px;">CE6000-40</td>
			<td>to pattern adhesive films</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Swingline paper cutter</td>
			<td style="width:135px;">Amazon</td>
			<td style="width:175px;">B0006VNY4C</td>
			<td>to cut paper or devices</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Epson Perfection V500 photo scanner</td>
			<td style="width:135px;">Amazon</td>
			<td style="width:175px;">B000VG4AY0</td>
			<td>to scan images of readout layer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">economy plier-action hole punch</td>
			<td style="width:135px;">McMaster-Carr</td>
			<td>3488A9</td>
			<td>to remove alignment holes&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">Whatman chromatogrpahy paper, Grade 4</td>
			<td style="width:135px;">Sigma Aldrich</td>
			<td>WHA1004917</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">Fisherbrand chromatography paper (thick)&#160;</td>
			<td style="width:135px;">Fisher Scientific</td>
			<td>05-714-4</td>
			<td>to function as blot layer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">Immunodyne ABC (0.45 &#181;m pore size )</td>
			<td style="width:135px;">Pall Corporation</td>
			<td>NBCHI3R</td>
			<td>to function as material for capture layer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">removable/permanent adhesive-double faced liner</td>
			<td style="width:135px;">FLEXcon</td>
			<td style="width:175px;">DF021621</td>
			<td>to facilitate peeling</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">permanent adhesive-double faced liner</td>
			<td style="width:135px;">FLEXcon</td>
			<td style="width:175px;">DF051521</td>
			<td></td>
		</tr>
		<tr height="18">
			<td height="18" style="height:19px;width:447px;">wax liner</td>
			<td style="width:135px;">FLEXcon</td>
			<td style="width:175px;">FLEXMARK 80 D/F PFW LINER</td>
			<td>to assist with patterning adhesive</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">acrylic sheet</td>
			<td style="width:135px;">McMaster-Carr</td>
			<td style="width:175px;">8560K266&#160;</td>
			<td>to fabricate frame</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">self-adhesive sheets</td>
			<td style="width:135px;">Fellowes</td>
			<td style="width:175px;">CRC52215</td>
			<td>to use as protective slip</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">absolute ethanol</td>
			<td style="width:135px;">VWR</td>
			<td style="width:175px;">89125-172</td>
			<td>to sanitize work area</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">bovine serum albumin</td>
			<td style="width:135px;">AMRESCO</td>
			<td style="width:175px;">0332</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sekisui Diagnostics OSOM hCG Urine Controls</td>
			<td style="width:135px;">Fisher Scientific</td>
			<td>22-071-066</td>
			<td>to use as positive and negative samples</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">anti-&#946;-hCG monoclonal antibody colloidal gold conjugate (clone 1)</td>
			<td style="width:135px;">Arista Biologicals&#160;</td>
			<td>CGBCG-0701</td>
			<td>to treat conjugate layer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">goat anti-&#945;-hCG antibody</td>
			<td style="width:135px;">Arista Biologicals&#160;</td>
			<td>ABACG-0500</td>
			<td>to treat capture layer</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">10X phosphate buffered saline</td>
			<td style="width:135px;">Fisher Scientific</td>
			<td style="width:175px;">BP3991</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">Oxoid skim milk powder</td>
			<td style="width:135px;">Thermo Scientific</td>
			<td style="width:175px;">OXLP0031B</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:447px;">Tween 20</td>
			<td style="width:135px;">AMRESCO</td>
			<td style="width:175px;">M147</td>
			<td></td>
		</tr>
	</tbody>
</table>

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.

Obtaining reproducible assay performances in three-dimensional paper-based microfluidic devices relies on a fabrication method that ensures consistency among devices. Towards this goal, we have identified a number of manufacturing processes and material considerations, and discuss them here in the context of demonstrating a paper-based immunoassay. We use a wax printing method to form hydrophobic barriers within paper-based microfluidic devices (Figure 2A).<sup class="xre...

Watch this Scientific Journal Video about Fabrication of Three-dimensional Paper-based Microfluidic Devices for Immunoassays at JoVE.com

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

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.

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

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