Posts Tagged ‘electrospinning’

Contraception and HIV protection in cloth*

Friday, November 30th, 2012

Researchers at the University of Washington have published a study in the peer-reviewed, open access journal, Public Library of Science ONE (PLoS ONE), concerning their work to produce fibres that can deliver both contraceptives and anti-HIV drugs, according to a Nov. 30, 2012 news item on Nanowerk,

The only way to protect against HIV and unintended pregnancy today is the condom. It’s an effective technology, but not appropriate or popular in all situations.

A University of Washington team has developed a versatile platform to simultaneously offer contraception and prevent HIV. Electrically spun cloth with nanometer-sized fibers can dissolve to release drugs, providing a platform for cheap, discrete and reversible protection.

Hannah Hickey’s  Nov. 30, 2012 University of Washington news release, which originated the news item, provides details,

“Our dream is to create a product women can use to protect themselves from HIV infection and unintended pregnancy,” said corresponding author Kim Woodrow, a UW assistant professor of bioengineering. “We have the drugs to do that. It’s really about delivering them in a way that makes them more potent, and allows a woman to want to use it.”

Electrospinning uses an electric field to catapult a charged fluid jet through air to create very fine, nanometer-scale fibers. The fibers can be manipulated to control the material’s solubility, strength and even geometry. Because of this versatility, fibers may be better at delivering medicine than existing technologies such as gels, tablets or pills. No high temperatures are involved, so the method is suitable for heat-sensitive molecules. The fabric can also incorporate large molecules, such as proteins and antibodies, that are hard to deliver through other methods.

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They first dissolved polymers approved by the Food and Drug Administration and antiretroviral drugs used to treat HIV to create a gooey solution that passes through a syringe. As the stream encounters the electric field it stretches to create thin fibers measuring 100 to several thousand nanometers that whip through the air and eventually stick to a collecting plate (one nanometer is about one 25-millionth of an inch). The final material is a stretchy fabric that can physically block sperm or release chemical contraceptives and antivirals.

“This method allows controlled release of multiple compounds,” Ball said. “We were able to tune the fibers to have different release properties.”

One of the fabrics they made dissolves within minutes, potentially offering users immediate, discrete protection against unwanted pregnancy and sexually transmitted diseases.

Another dissolves gradually over a few days, providing an option for sustained delivery, more like the birth-control pill,  to provide contraception and guard against HIV.

The fabric could incorporate many fibers to guard against many different sexually transmitted infections, or include more than one anti-HIV drug to protect against drug-resistant strains (and discourage drug-resistant strains from emerging). Mixed fibers could be designed to release drugs at different times to increase their potency, like the prime-boost method used in vaccines.

The electrospun cloth could be inserted directly in the body or be used as a coating on vaginal rings or other products.

Electrospinning has existed for decades, but it’s only recently been automated to make it practical for applications such as filtration and tissue engineering. This is the first study to use nanofibers for vaginal drug delivery.

While this technology is more discrete than a condom, and potentially more versatile than pills or plastic or rubber devices, researchers say there is no single right answer.

The citation and link to the article,

Drug-Eluting Fibers for HIV-1 Inhibition and Contraception by Cameron Ball, Emily Krogstad, Thanyanan Chaowanachan, Kim A. Woodrow (2012) PLoS ONE 7(11): e49792. doi:10.1371/journal.pone.0049792

Last month, the Bill and Melinda Gates Foundation awarded these researchers a $1M grant to pursue this work.

*ETA Dec.2.12: I erroneously used the word clothing in the headline. It’s now been corrected to ‘cloth’.

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Printing new knee cartilage

Tuesday, November 27th, 2012

I was reminded of the 1992 Olympics in Barcelona while reading the Nov. 22, 2012 news item on Nanowerk about printing cartilage for knees. Some years ago I knew a Canadian wrestler who’d participated in those games and he had a story about knee cartilage that featured amputation.

Apparently, wrestlers in earlier generations had knee surgeries that involved removal of cartilage for therapeutic purposes. Unfortunately, decades later, these retired wrestlers found that whatever cartilage had remained was now worn through and bones were grinding on bones causing such pain that more than one wrestler agreed to amputation. I never did check out the story but it rang true largely because I’d come across a similar story from a physiotherapist regarding  a shoulder joint and the consequences of losing cartilage in there (very, very painful).

It seems that scientists are now working on a solution for those of us unlucky enough to have damaged or worn through cartilage in our joints, from the Nov. 22, 2012 IOP science news release, (Institute of Physics) which originated the news item,

The printing of 3D tissue has taken a major step forward with the creation of a novel hybrid printer that simplifies the process of creating implantable cartilage.

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The printer is a combination of two low-cost fabrication techniques: a traditional ink jet printer and an electrospinning machine. Combining these systems allowed the scientists to build a structure made from natural and synthetic materials. …

In this study, the hybrid system produced cartilage constructs with increased mechanical stability compared to those created by an ink jet printer using gel material alone. The constructs were also shown to maintain their functional characteristics in the laboratory and a real-life system.

The key to this was the use of the electrospinning machine, which uses an electrical current to generate very fine fibres from a polymer solution. Electrospinning allows the composition of polymers to be easily controlled and therefore produces porous structures that encourage cells to integrate into surrounding tissue.

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In this study, flexible mats of electrospun synthetic polymer were combined, layer-by-layer, with a solution of cartilage cells from a rabbit ear that were deposited using the traditional ink jet printer. The constructs were square with a 10cm diagonal and a 0.4mm thickness.

The researchers tested their strength by loading them with variable weights and, after one week, tested to see if the cartilage cells were still alive.

The constructs were also inserted into mice for two, four and eight weeks to see how they performed in a real life system. After eight weeks of implantation, the constructs appeared to have developed the structures and properties that are typical of elastic cartilage, demonstrating their potential for insertion into a patient.

The researchers state that in a future scenario, cartilage constructs could be clinically applied by using an MRI scan of a body part, such as the knee, as a blueprint for creating a matching construct. A careful selection of scaffold material for each patient’s construct would allow the implant to withstand mechanical forces while encouraging new cartilage to organise and fill the defect.

The researchers’ article in the IOP science jouBiofrarnal, Biofabrication, is freely available for 30 days after its date of publication, Nov. 21, 2012. You do need to register with IOP science to gain access. Here’s the citation and a link,

Hybrid printing of mechanically and biologically improved constructs for cartilage tissue engineering applications by Tao Xu, Kyle W Binder, Mohammad Z Albanna, Dennis Dice, Weixin Zhao, James J Yoo and Anthony Atala in 2013 Biofabrication 5 015001 doi:10.1088/1758-5082/5/1/015001

I believe all of the scientists involved in this bioprinting project are with the Wake Forest Institute for Regenerative Medicine.

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A breath-based and handheld diagnostic device

Tuesday, May 8th, 2012

Researcher Perena Gouma and her team at Stony Brook University (New York, US) are hoping that eventually their device will be available over the counter so anyone will be able to perform a preliminary diagnostic test as casually as you take a breath. From the May 7, 2012 news item on Nanowerk,

You blow into a small valve attached to a box that is about half the size of your typical shoebox and weighs less than one pound. Once you blow into it, the lights on top of the box will give you an instant readout. A green light means you pass (and your bad breath is not indicative of an underlying disease; perhaps it’s just a result of the raw onions you ingested recently); however, a red light means you might need to take a trip to the doctor’s office to check if something more serious is an issue.

Here’s a bit more about the device and the researchers’ hopes in a video from the US National Science Foundation (NSF) featuring the NSF’s Miles O’Brien as the reporter,

O’Brien in his May 7, 2012 article for the NSF’s Science Nation online magazine describes the technology,

With support from the National Science Foundation (NSF), Professor Perena Gouma and her team at Stony Brook University in New York developed a sensor chip that you might say is the “brain” of the breathalyzer. It’s coated with tiny nanowires that look like microscopic spaghetti and are able to detect minute amounts of chemical compounds in the breath. “These nanowires enable the sensor to detect just a few molecules of the disease marker gas in a ‘sea’ of billions of molecules of other compounds that the breath consists of,” Gouma explains. This is what nanotechnology is all about.

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The manufacturing process that creates the single crystal nanowires is called “electrospinning.” It starts with a liquid compound being shot from a syringe into an electrical field. The electric field crystallizes the inserted liquid into a tiny thread or “wire” that collects onto an aluminum backing. Gouma says enough nanowire can be produced in one syringe to stretch from her lab in Stony Brook, N.Y. to the moon and still be a single grain (monocrystal).

“There can be different types of nanowires, each with a tailored arrangement of metal and oxygen atoms along their configuration, so as to capture a particular compound,” explains Gouma. “For example, some nanowires might be able to capture ammonia molecules, while others capture just acetone and others just the nitric oxide. Each of these biomarkers signal a specific disease or metabolic malfunction so a distinct diagnostic breathalyzer can be designed.”

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Gouma also says the nanowires can be rigged to detect infectious viruses and microbes like Salmonella, E. coli or even anthrax. “There will be so many other applications we haven’t envisioned. It’s very exciting; it’s a whole new world,” she says.

I think most (if not all) of the handheld diagnostic projects I’ve covered have been fluids-based, i.e., they need a sample of saliva, blood, urine, etc. to perform their diagnostic function. I believe this is the first breath-based project I’ve seen.

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