{"id":7062,"date":"2015-12-22T05:55:49","date_gmt":"2015-12-22T05:55:49","guid":{"rendered":"http:\/\/revoscience.com\/en\/?p=7062"},"modified":"2015-12-22T05:55:49","modified_gmt":"2015-12-22T05:55:49","slug":"new-device-uses-carbon-nanotubes-to-snag-molecules","status":"publish","type":"post","link":"https:\/\/www.revoscience.com\/en\/new-device-uses-carbon-nanotubes-to-snag-molecules\/","title":{"rendered":"New device uses carbon nanotubes to snag molecules"},"content":{"rendered":"

Nanotube \u201cforest\u201d in a microfluidic channel may help detect rare proteins and viruses<\/strong><\/em><\/span><\/p>\n

\"A<\/a>
A patterned and cylindrical structure made up of carbon nanotubes.
Courtesy of the researchers<\/figcaption><\/figure>\n

CAMBRIDGE, Mass.<\/strong> —\u00a0Engineers at MIT have devised a new technique for trapping hard-to-detect molecules, using forests of carbon nanotubes.<\/span><\/p>\n

The team modified a simple microfluidic channel with an array of vertically aligned carbon nanotubes \u2014 rolled lattices of carbon atoms that resemble tiny tubes of chicken wire. The researchers had previously devised a method for standing carbon nanotubes on their ends, like trees in a forest. With this method, they created a three-dimensional array of permeable carbon nanotubes within a microfluidic device, through which fluid can flow.<\/span><\/p>\n

Now, in a study published in the\u00a0Journal of Microengineering and Nanotechnology,\u00a0<\/em>the researchers have given the nanotube array the ability to trap certain particles. To do this, the team coated the array, layer by layer, with polymers of alternating electric charge.<\/span><\/p>\n

\u201cYou can think of each nanotube in the forest as being concentrically coated with different layers of polymer,\u201d says Brian Wardle, professor of aeronautics and astronautics at MIT. \u201cIf you drew it in cross-section, it would be like rings on a tree.\u201d<\/span><\/p>\n

[pullquote]Depending on the number of layers deposited, the researchers can create thicker or thinner nanotubes and thereby tailor the porosity of the forest to capture larger or smaller particles of interest.\u00a0[\/pullquote]<\/p>\n

Depending on the number of layers deposited, the researchers can create thicker or thinner nanotubes and thereby tailor the porosity of the forest to capture larger or smaller particles of interest.\u00a0<\/span><\/p>\n

The nanotubes\u2019 polymer coating may also be chemically manipulated to bind specific bioparticles flowing through the forest. To test this idea, the researchers applied an established technique to treat the surface of the nanotubes with antibodies that bind to prostate specific antigen (PSA), a common experimental target. The polymer-coated arrays captured 40 percent more antigens, compared with arrays lacking the polymer coating.<\/span><\/p>\n

Wardle says the combination of carbon nanotubes and multilayer coatings may help finely tune microfluidic devices to capture extremely small and rare particles, such as certain viruses and proteins.<\/span><\/p>\n

\u201cThere are smaller bioparticles that contain very rich amounts of information that we don\u2019t currently have the ability to access in point-of-care [medical testing] devices like microfluidic chips,\u201d says Wardle, who is a co-author on the paper. \u201cCarbon nanotube arrays could actually be a platform that could target that size of bioparticle.\u201d<\/span><\/p>\n

The paper\u2019s lead author is Allison Yost, a former graduate student who is currently an engineer at Accion Systems. Others on the paper include graduate student Setareh Shahsavari; postdoc Roberta Polak; School of Engineering Professor of Teaching Innovation Gareth McKinley; professor of materials science and engineering Michael Rubner, and Raymond A. And Helen E. St. Laurent Professor of Chemical Engineering Robert Cohen.<\/span><\/p>\n

A porous forest<\/strong><\/span><\/p>\n

Carbon nanotubes have been a subject of intense scientific study, as they possess exceptional electrical, mechanical, and optical properties. While their use in microfluidics has not been well explored, Wardle says carbon nanotubes are an ideal platform because their properties may be manipulated to attract certain nanometer-sized molecules. Additionally, carbon nanotubes are 99 percent porous, meaning a nanotube is about 1 percent carbon and 99 percent air.<\/span><\/p>\n

\u201cWhich is what you need,\u201d Wardle says. \u201cYou need to flow quantities of fluid through this material to shed all the millions of particles you don\u2019t want to find and grab the one you do want to find.\u201d<\/span><\/p>\n

What\u2019s more, Wardle says, a three-dimensional forest of carbon nanotubes would provide much more surface area on which target molecules may interact, compared with the two-dimensional surfaces in conventional microfluidics.<\/span><\/p>\n

\u201cThe capture efficiency would scale with surface area,\u201d Wardle notes.<\/span><\/p>\n

A versatile array<\/strong><\/span><\/p>\n

The team integrated a three-dimensional array of carbon nanotubes into a microfluidic device by using chemical vapor deposition and photolithography to grow and pattern carbon nanotubes onto silicon wafers. They then grouped the nanotubes into a cylinder-shaped forest, measuring about 50 micrometers tall and 1 millimeter wide, and centered the array within a 3 millimeter-wide, 7-millimeter long microfluidic channel.<\/span><\/p>\n

The researchers coated the nanotubes in successive layers of alternately charged polymer solutions in order to create distinct, binding layers around each nanotube. To do so, they flowed each solution through the channel and found they were able to create a more uniform coating with a gap between the top of the nanotube forest and the roof of the channel. Such a gap allowed solutions to flow over, then down into the forest, coating each individual nanotube. In the absence of a gap, solutions simply flowed around the forest, coating only the outer nanotubes.<\/span><\/p>\n

After coating the nanotube array in layers of polymer solution, the researchers demonstrated that the array could be primed to detect a given molecule, by treating it with antibodies that typically bind to prostate specific antigen (PSA). They pumped in a solution containing small amounts of PSA and found that the array captured the antigen effectively, throughout the forest, rather than just on the outer surface of a typical microfluidic element.<\/span><\/p>\n

Wardle says that the nanotube array is extremely versatile, as the carbon nanotubes may be manipulated mechanically, electrically, and optically, while the polymer coatings may be chemically altered to capture a wide range of particles. He says an immediate target may be biomarkers called exosomes, which are less than 100 nanometers wide and can be important signals of a disease\u2019s progression.<\/span><\/p>\n

\u201cScience is really picking up on how much information these particles contain, and they\u2019re sort of everywhere, but really hard to find, even with large-scale equipment,\u201d Wardle says. \u201cThis type of device actually has all the characteristics and functionality that would allow you to go after bioparticles like exosomes and things that really truly are nanometer scale.\u201d<\/span><\/p>\n

This research was funded, in part, by the National Science Foundation.<\/span><\/p>\n","protected":false},"excerpt":{"rendered":"

Engineers at MIT have devised a new technique for trapping hard-to-detect molecules, using forests of carbon nanotubes.<\/p>\n","protected":false},"author":6,"featured_media":7063,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[14,17],"tags":[],"class_list":["post-7062","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-innovation","category-research"],"featured_image_urls":{"full":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0.jpg",639,426,false],"thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0-150x150.jpg",150,150,true],"medium":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0-300x200.jpg",300,200,true],"medium_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0.jpg",639,426,false],"large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0.jpg",639,426,false],"1536x1536":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0.jpg",639,426,false],"2048x2048":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0.jpg",639,426,false],"ultp_layout_landscape_large":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0.jpg",639,426,false],"ultp_layout_landscape":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0.jpg",639,426,false],"ultp_layout_portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0.jpg",600,400,false],"ultp_layout_square":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0.jpg",600,400,false],"newspaper-x-single-post":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0.jpg",639,426,false],"newspaper-x-recent-post-big":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0.jpg",540,360,false],"newspaper-x-recent-post-list-image":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0.jpg",95,63,false],"web-stories-poster-portrait":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0.jpg",639,426,false],"web-stories-publisher-logo":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0.jpg",96,64,false],"web-stories-thumbnail":["https:\/\/www.revoscience.com\/en\/wp-content\/uploads\/2015\/12\/MIT-Nano-BioDetection-1_0.jpg",150,100,false]},"author_info":{"info":["Amrita Tuladhar"]},"category_info":"Innovation<\/a> Research<\/a>","tag_info":"Research","comment_count":"0","_links":{"self":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/7062","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/comments?post=7062"}],"version-history":[{"count":0,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/posts\/7062\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media\/7063"}],"wp:attachment":[{"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/media?parent=7062"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/categories?post=7062"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.revoscience.com\/en\/wp-json\/wp\/v2\/tags?post=7062"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}