Tag Archives: Columbia University

Cartilage; the ‘official tissue’ of tissue engineering

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What is this fascination with cartilage? For the second time this week (see yesterday’s [April 30, 2014] posting: Replacement cartilage grown on laboratory chip)  there’s a news item about a team, this time from Columbia University School of Engineering and Applied Sciences (aka Columbia Engineering), growing cartilage. From an April 30, 2014 news item on ScienceDaily,

Researchers at Columbia Engineering announced today that they have successfully grown fully functional human cartilage in vitro from human stem cells derived from bone marrow tissue. Their study, which demonstrates new ways to better mimic the enormous complexity of tissue development, regeneration, and disease, is published in the April 28 Early Online edition of Proceedings of the National Academy of Sciences (PNAS).

“We’ve been able — for the first time — to generate fully functional human cartilage from mesenchymal stem cells by mimicking in vitro the developmental process of mesenchymal condensation,” says Gordana Vunjak-Novakovic, who led the study and is the Mikati Foundation Professor of Biomedical Engineering at Columbia Engineering and professor of medical sciences. “This could have clinical impact, as this cartilage can be used to repair a cartilage defect, or in combination with bone in a composite graft grown in lab for more complex tissue reconstruction.”

An April 30, 2014 Columbia Engineering news release by Holly Evans, which originated the news item, provides some insight into the issues associated with tissue engineering and cartilage,

For more than 20 years, researchers have unofficially called cartilage the “official tissue of tissue engineering,” Vunjak-Novakovic observes. [emphasis mine] Many groups studied cartilage as an apparently simple tissue: one single cell type, no blood vessels or nerves, a tissue built for bearing loads while protecting bone ends in the joints. While there has been great success in engineering pieces of cartilage using young animal cells, no one has, until now, been able to reproduce these results using adult human stem cells from bone marrow or fat, the most practical stem cell source. Vunjak-Novakovic’s team succeeded in growing cartilage with physiologic architecture and strength by radically changing the tissue-engineering approach.

The general approach to cartilage tissue engineering has been to place cells into a hydrogel and culture them in the presence of nutrients and growth factors and sometimes also mechanical loading. But using this technique with adult human stem cells has invariably produced mechanically weak cartilage. So Vunjak-Novakovic and her team, who have had a longstanding interest in skeletal tissue engineering, wondered if a method resembling the normal development of the skeleton could lead to a higher quality of cartilage.

(I love the combination of “unofficially” with “official.”) Getting back to the cartilage research, the news release goes on to describe a new technique for engineering cartilage,

Sarindr Bhumiratana, postdoctoral fellow in Vunjak-Novakovic’s Laboratory for Stem Cells and Tissue Engineering, came up with a new approach: inducing the mesenchymal stem cells to undergo a condensation stage as they do in the body before starting to make cartilage. He discovered that this simple but major departure from how things were usually being done resulted in a quality of human cartilage not seen before.

Gerard Ateshian, Andrew Walz Professor of Mechanical Engineering, professor of biomedical engineering, and chair of the Department of Mechanical Engineering, and his PhD student, Sevan Oungoulian, helped perform measurements showing that the lubricative property and compressive strength—the two important functional properties—of the tissue-engineered cartilage approached those of native cartilage. The researchers then used their method to regenerate large pieces of anatomically shaped and mechanically strong cartilage over the bone, and to repair defects in cartilage.

“Our whole approach to tissue engineering is biomimetic in nature, which means that our engineering designs are defined by biological principles,” Vunjak-Novakovic notes. “This approach has been effective in improving the quality of many engineered tissues—from bone to heart. Still, we were really surprised to see that our cartilage, grown by mimicking some aspects of biological development, was as strong as ‘normal’ human cartilage.”

The team plans next to test whether the engineered cartilage tissue maintains its structure and long-term function when implanted into a defect.

Here’s a link to and a citation for the research paper,

Large, stratified, and mechanically functional human cartilage grown in vitro by mesenchymal condensation by Sarindr Bhumiratana, Ryan E. Eton, Sevan R. Oungoulian, Leo Q. Wan, Gerard A. Ateshian, and Gordana Vunjak-Novakovic. Proceedings of the National Academy of Sciences, 2014; DOI: 10.1073/pnas.1324050111

This paper is behind a paywall.

I have an observation about both this and the other cartilage story (Replacement cartilage grown on laboratory chip) featured here. It looks to me as if these two areas of research could be complementary. The ‘laboratory chip’ story is about a new way to use 3D printing to produce cartilage more quickly where this Columbia Engineering story is about better mimicking processes in the body to engineer stronger, more resilient cartilage. Taken separately or together cartilage tissue engineering has had an exciting week.

World’s* smallest FM radio transmitter made out of graphene

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I’m always amazed at how often nanotechnology is paired with radio. The latest ‘nanoradio’ innovation is from the University of Columbia School of Engineering. According to a November 18, 2013 news item on ScienceDaily,

 A team of Columbia Engineering researchers, led by Mechanical Engineering Professor James Hone and Electrical Engineering Professor Kenneth Shepard, has taken advantage of graphene’s special properties — its mechanical strength and electrical conduction — and created a nano-mechanical system that can create FM signals, in effect the world’s smallest FM radio transmitter.

One of my first ‘nanorado’ stories (in 2007 and predating the existence of this blog) focused on carbon nanotubes and a Zettl Group (Alex Zettl) project at the University of California at Berkeley (from the Zettl Group’s Nanotube Radio: Supplementary materials webpage),

We have constructed a fully functional, fully integrated radio receiver, orders-of-magnitude smaller than any previous radio, from a single carbon nanotube. The single nanotube serves, at once, as all major components of a radio: antenna, tuner, amplifier, and demodulator. Moreover, the antenna and tuner are implemented in a radically different manner than traditional radios, receiving signals via high frequency mechanical vibrations of the nanotube rather than through traditional electrical means. We have already used the nanotube radio to receive and play music from FM radio transmissions such as Layla by Eric Clapton (Derek and the Dominos) and the Beach Boy’s Good Vibrations. The nanotube radio’s extremely small size could enable radical new applications such as radio controlled devices small enough to exist in the human bloodstream, or simply smaller, cheaper, and more efficient wireless devices such as cellular phones.

The group features four songs transmitted via their carbon nanotube radio (from the ‘supplementary materials’ webpage),

A high resolution transmission electron microscope allows us to observe the nanotube radio in action. We have recorded four videos from the electron microscope of the nanotube radio playing four different songs. At the beginning of each video, the nanotube radio is tuned to a different frequency than that of the transmitted radio signal. Thus, the nanotube does not vibrate, and only static noise can be heard. As the radio is brought into tune with the transmitted signal, the nanotube begins to vibrate, which blurs its image in the video, and at the same time, the music becomes audible. The four songs are Good Vibrations by the Beach Boys, Largo from the opera Xerxes by Handel (this was the first song ever transmitted using radio), Layla by Eric Clapton (Derek & the Dominos), and the Main Title from Star Wars by John Williams.

Good Vibrations (Quicktime, 8.06 MB)
Layla (Quicktime, 6.13 MB)
Largo (Quicktime, 8.73 MB)
Star Wars (Quicktime, 8.68 MB)

‘Layla’ is quite scrtachy and barely audible but it is there, if you care to listen to this 2007 carbon nanotube radio project. Now in 2013 we have a graphene radio receiver and this graphene radio project is intended to achieve some of the goals as the carbon nanotube radio project,. From the Nov. 17, 2013 University of Columbia news release on newswise and also on EurekAlert),

“This work is significant in that it demonstrates an application of graphene that cannot be achieved using conventional materials,” Hone says. “And it’s an important first step in advancing wireless signal processing and designing ultrathin, efficient cell phones. Our devices are much smaller than any other sources of radio signals, and can be put on the same chip that’s used for data processing.”

Graphene, a single atomic layer of carbon, is the strongest material known to man, and also has electrical properties superior to the silicon used to make the chips found in modern electronics. The combination of these properties makes graphene an ideal material for nanoelectromechanical systems (NEMS), which are scaled-down versions of the microelectromechanical systems (MEMS) used widely for sensing of vibration and acceleration. For example, Hone explains, MEMS sensors figure out how your smartphone or tablet is tilted to rotate the screen.

In this new study, the team took advantage of graphene’s mechanical ‘stretchability’ to tune the output frequency of their custom oscillator, creating a nanomechanical version of an electronic component known as a voltage controlled oscillator (VCO). With a VCO, explains Hone, it is easy to generate a frequency-modulated (FM) signal, exactly what is used for FM radio broadcasting. The team built a graphene NEMS whose frequency was about 100 megahertz, which lies right in the middle of the FM radio band (87.7 to 108 MHz). They used low-frequency musical signals (both pure tones and songs from an iPhone) to modulate the 100 MHz carrier signal from the graphene, and then retrieved the musical signals again using an ordinary FM radio receiver.

“This device is by far the smallest system that can create such FM signals,” says Hone.

While graphene NEMS will not be used to replace conventional radio transmitters, they have many applications in wireless signal processing. Explains Shepard, “Due to the continuous shrinking of electrical circuits known as ‘Moore’s Law’, today’s cell phones have more computing power than systems that used to occupy entire rooms. However, some types of devices, particularly those involved in creating and processing radio-frequency signals, are much harder to miniaturize. These ‘off-chip’ components take up a lot of space and electrical power. In addition, most of these components cannot be easily tuned in frequency, requiring multiple copies to cover the range of frequencies used for wireless communication.”

…

Unfortunately I haven’t seen any audio files for this ‘graphene radio’ but here’s a link to and a citation for the 2013 paper ,

Graphene mechanical oscillators with tunable frequency by Changyao Chen, Sunwoo Lee, Vikram V. Deshpande, Gwan-Hyoung Lee, Michael Lekas, Kenneth Shepard, & James Hone. Nature Nanotechnology (2013) doi:10.1038/nnano.2013.232 Published online 17 November 2013

The paper is behind a paywall.

* ‘Wolrd’s’ in headline corrected to ‘World’s’ on July 29, 2015.

Materials research and nanotechnology for clean energy at Addis Ababa University (Ethiopia)

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Getting to the bottom line of a complex set of  interlinked programs and initiatives, it’s safe to say that a group of US students went to study with research Addis Ababa University (Ethiopia) in the first Materials Research School which was held Dec. 9 -21, 2012.

Rutgers University (New Jersey, US)  student Aleksandra Biedron attended the Materials Research School as a member of a joint Rutgers University-Princeton University Nanotechnology for Clean Energy graduate training program (one of the US National Science Foundation’s Integrative Graduate Education Research Traineeship [IGERT] programs).

In a Summer 2013 (volume 14) issue of Rutgers University’s Chemistry and Chemical Biology News, Biedron describes the experience,

The program brought together approximately 50 graduate students and early-career materials researchers from across the United States and East Africa, as well as 15 internationally recognized instructors, for two weeks of lectures, problem solving, and cultural exchange. “I was interested in meeting young African scientists to discuss energy materials, a universal concern, which is relevant to my research in ionic liquids,” said Biedron, a graduate of Livingston High School [Berkeley Heights, New Jersey]. “I was also excited to see Addis Ababa, Ethiopia, and experience the culture and historical attractions.”

A cornerstone of the Nanotechnology for Clean Energy IGERT program is having the students apply their training in a dynamic educational exchange program with African institutions, promoting development of the students’ global awareness and understanding of the challenges involved in global scientific and economic development. In Addis Ababa, Biedron quickly noticed how different the scope of research was between the African scientists and their international counterparts.

“The African scientists’ research was really solution-based,” said Biedron. “They were looking at how they could use their natural resources to solve some of their region’s most pressing issues, not only for energy, but also health, clean water, and housing. You don’t really see that as much in the U.S. because we are already thinking about the future, 10 or 20 years from now.”

H/T centraljerseycentral.com, Aug. 1, 2013 news item.

I found a little more information about the first Materials Research School on this Columbia University JUAMI (Joint US-Africa Materials Initiative) webpage,

The Joint US-Africa Materials Initiative
Announces its first Materials Research School
To be held in Addis Ababa, Ethiopia, December 9-21, 2012

Theme of the school:

The first school will concentrate on materials research for sustainable energy. Tutorials and seminar topics will range from photocatalysis and photovoltaics to fuel cells and batteries.

Goals of the school:

The initiative aims to build materials science research and collaborations between the United States and Africa, with an initial focus on East Africa, and to develop ties between young materials researchers in both regions in a school taught by top materials researchers. The school will bring together approximately 50 PhD and early career materials researchers from across the US and East Africa, and 15 internationally recognized instructors, for two weeks of lectures, problem solving and cultural exchange in historic Addis Ababa, Ethiopia. Topics include photocatalysis, photovoltaics, thermoelectrics, fuel cells, and batteries.

I also found this on the IGERT homepage,

IGERT Trainees participate in:
  • Interdisciplinary courses in the fundamentals of energy technology, nanotechnology and energy policy.
  • Dissertation research emphasizing nanotechnology and energy.
  • Dynamic educational exchange between U.S. and select African institutions.

New paradigm for low power telecommunications

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I’m always a sucker for the nonlinear although I’m much more familiar with nonlinear narratives than I am with nonlinear photonics. From the July 15, 2012 news item on EurekAlert,

New research by Columbia Engineering demonstrates remarkable optical nonlinear behavior of graphene that may lead to broad applications in optical interconnects and low-power photonic integrated circuits. With the placement of a sheet of graphene just one-carbon-atom-thick, the researchers transformed the originally passive device into an active one that generated microwave photonic signals and performed parametric wavelength conversion at telecommunication wavelengths.

“We have been able to demonstrate and explain the strong nonlinear response from graphene, which is the key component in this new hybrid device,” says Tingyi Gu, the study’s lead author and a Ph.D. candidate in electrical engineering. “Showing the power-efficiency of this graphene-silicon hybrid photonic chip is an important step forward in building all-optical processing elements that are essential to faster, more efficient, modern telecommunications. And it was really exciting to explore the ‘magic’ of graphene’s amazingly conductive properties and see how graphene can boost optical nonlinearity, a property required for the digital on/off two-state switching and memory.”

Here’s one of the issues that scientists have been grappling with,

Until recently, researchers could only isolate graphene as single crystals with micron-scale dimensions, essentially limiting the material to studies confined within laboratories. “The ability to synthesize large-area films of graphene has the obvious implication of enabling commercial production of these proven graphene-based technologies,” explains James Hone, associate professor of mechanical engineering, whose team provided the high quality graphene for this study. “But large-area films of graphene can also enable the development of novel devices and fundamental scientific studies requiring graphene samples with large dimensions. This work is an exciting example of both—large-area films of graphene enable the fabrication of novel opto-electronic devices, which in turn allow for the study of scientific phenomena.”

Building on the work done by scientists such as Hone,this new group of researchers led by by Chee Wei Wong, professor of mechanical engineering, director of the Center for Integrated Science and Engineering, and Solid-State Science and Engineering at Columbia University, created a new device,

They have engineered a graphene-silicon device whose optical nonlinearity enables the system parameters (such as transmittance and wavelength conversion) to change with the input power level. The researchers also were able to observe that, by optically driving the electronic and thermal response in the silicon chip, they could generate a radio frequency carrier on top of the transmitted laser beam and control its modulation with the laser intensity and color. Using different optical frequencies to tune the radio frequency, they found that the graphene-silicon hybrid chip achieved radio frequency generation with a resonant quality factor more than 50 times lower than what other scientists have achieved in silicon.

“We are excited to have observed four-wave mixing in these graphene-silicon photonic crystal nanocavities,” says Wong. “We generated new optical frequencies through nonlinear mixing of two electromagnetic fields at low operating energies, allowing reduced energy per information bit. This allows the hybrid silicon structure to serve as a platform for all-optical data processing with a compact footprint in dense photonic circuits.”

That bit about the system parameters changing with input levels suggests a biological system responding sensitively to environmental inputs, e.g., when it gets hot, your body tries to cool itself down in a sensitive response to an input. Of course, that fanciful analogy doesn’t extend itself too far since the human body is trying to return to its internal balance point (homeostasis) which isn’t what the Columbia researchers are attempting to do with their device.

Diagnostics on a credit card?

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Diagnostic equipment keeps getting smaller with the latest being the size of a credit card (more or less). It’s called an ‘mChip’ and can be used to diagnose either HIV or syphillis. From the August 2, 2011 article by Ariel Schwartz on Fast Company,

If you were concerned you had HIV (and lived in America), it would be easy enough to get some blood drawn at a clinic near your house, and wait a few days (or even hours) for the results. But in Africa, many clinics and hospitals have to send out blood samples to a national lab. It’s a process that can take weeks, and patients in remote areas sometimes don’t even bother to make the trek back to the clinic to get results. On a continent with a rampant HIV epidemic, this is a big problem. But Columbia University researchers have a partial solution–a $1 plastic chip that can diagnose HIV and syphilis in 15 minutes.

The “mChip”, a credit-card-sized piece of plastic that is produced using a plastic injection molding process, tests for multiple diseases with just one pinprick of blood.

The international team working on this project was led by professor of bioengineering at Columbia University, Samuel Sia. Field testing of the mChip took place in Rwanda. GrrlScientist in her August 3, 2011 posting (at the Guardian Science blogs site) offers more technical details,

“The microfluidic design is very simple”, said Dr Sia. “It’s essentially a .. linear channel that’s been looped around in various ways.”

… This credit card-sized cassette is manufactured from plastic and each mChip cassette can test seven samples (one per channel), and requires no moving parts, electricity or external instrumentation. Instead, it has small holes moulded into the plastic so reagent-loaded tubes can be attached. …

The principles for how the mChip work are well known, straightforward and, quite frankly, beautiful.

The mChip can be used for other diagnostic tests. A prostate cancer testing mChip has already been approved for use and other tests are being developed as well.

Sia’s team is not the only one working on faster, cheaper, more reliable diagnostic tests. A team at the University of Georgia (US)  has just published research about their flu detection test (from the August 3, 2011 news item on Nanowerk),

A new detection method developed at the University of Georgia and detailed in the August edition of the journal Analyst (“One-step assay for detecting influenza virus using dynamic light scattering and gold nanoparticles”), however, offers the best of both worlds. By coating gold nanoparticles with antibodies that bind to specific strains of the flu virus and then measuring how the particles scatter laser light, the technology can detect influenza in minutes at a cost of only a fraction of a penny per exam.

“We’ve known for a long time that you can use antibodies to capture viruses and that nanoparticles have different traits based on their size,” said study co-author Ralph Tripp, Georgia Research Alliance Eminent Scholar in Vaccine Development in the UGA College of Veterinary Medicine. “What we’ve done is combine the two to create a diagnostic test that is rapid and highly sensitive.”

Sia’s team seems to have worked on both the test and diagnostic device whereas some teams like the one in Georgia focus on tests or like the team at Stanford (mentioned in my March 1, 2011 posting about their nanoLAB) focus on the device.

Not all of these new handheld diagnostic tools and tests are designed for disease identification. Argento (mentioned in my February 15, 2011 posting) is being used by UK Sport to assist their elite athletes prior to the 2012 Olympics.  Locally, i.e., in Vancouver, there’s a team at St. Paul’s Hospital, PROOF (mentioned in my Feb. 15, 2011 posting), working on a test that would eliminate the need for monthly biopsies for patients who have received kidney transplants.