Tag Archives: silk

Tooth tattoos at Tufts University

In spring 2012, there was a fluttering in the blogosphere about tooth tattoos with the potential for monitoring dental health. As sometimes happens, I put off posting about the work until it seemed everyone else had written about it (e.g. Mar. 30, 2012 posting by Dexter Johnson for his Nanoclast blog on the IEEE website) and there was nothing left for me to say.  Happily, the researchers at Tufts University (where part of this research [Princeton University is also involved] is being pursued) have released more information in a Nov. 1, 2012 news article by David Levin,

The sensor, dubbed a “tooth tattoo,” was developed by the Princeton nanoscientist Michael McAlpine and Tufts bioengineers Fiorenzo Omenetto, David Kaplan and Hu Tao. The team first published their research last spring in the journal Nature Communications.

The sensor is relatively simple in its construction, says McAlpine. It’s made up of just three layers: a sheet of thin gold foil electrodes, an atom-thick layer of graphite known as graphene and a layer of specially engineered peptides, chemical structures that “sense” bacteria by binding to parts of their cell membranes.

“We created a new type of peptide that can serve as an intermediary between bacteria and the sensor,” says McAlpine. “At one end is a molecule that can bond with the graphene, and at the other is a molecule that bonds with bacteria,” allowing the sensor to register the presence of bacteria, he says.

Because the layers of the device are so thin and fragile, they need to be mounted atop a tough but flexible backing in order to transfer them to a tooth. The ideal foundation, McAlpine says, turns out to be silk—a substance with which Kaplan and Omenetto have been working for years.

By manipulating the proteins that make up a single strand of silk, it’s possible to create silk structures in just about any shape, says Omenetto, a professor of biomedical engineering at Tufts. Since 2005, he’s created dozens of different structures out of silk, from optical lenses to orthopedic implants. Silk is “kind of like plastic, in that we can make [it] do almost anything,” he says. “We have a lot of control over the material. It can be rigid. It can be flexible. We can make it dissolve in water, stay solid, become a gel—whatever we need.”

Omenetto, Kaplan and Tao created a thin, water-soluble silk backing for McAlpine’s bacterial sensor—a film that’s strong enough to hold the sensor components in place, but soft and pliable enough to wrap easily around the irregular contours of a tooth.

To apply the sensor, McAlpine says, you need only to wet the surface of the entire assembly—silk, sensor and all—and then press it onto the tooth. Once there, the silk backing will dissolve within 15 or 20 minutes, leaving behind the sensor, a rectangle of interwoven gold and black electrodes about half the size of a postage stamp and about as thick as a sheet of paper. The advantage of being attached directly to a tooth means that the sensor is in direct contact with bacteria in the mouth—an ideal way to monitor oral health.

Because the sensor doesn’t carry any onboard batteries, it must be both read and powered simultaneously through a built-in antenna. Using a custom-made handheld device about the size of a TV remote, McAlpine’s team can “ping” that antenna with radio waves, causing it to resonate electronically and send back information that the device then uses to determine if bacteria are present.

The sensor (A), attached to a tooth (B) and activated by radio signals (C), binds with certain bacteria (D). Illustration: Manu Mannoor/Nature Communications (downloaded from http://now.tufts.edu/articles/tooth-tattoo)

In addition to its potential for  monitoring dental health, the tooth tattoo could replace some of the more invasive health monitoring techniques (e.g., drawing blood), from the Tufts University article,

In addition to monitoring oral health, Kugel [Gerard Kugel, Tufts professor of prosthodontics and operative dentistry and associate dean for research at Tufts School of Dental Medicine] believes the tooth tattoo might be useful for monitoring a patient’s overall health. Biological markers for many diseases—from stomach ulcers to AIDS—appear in human saliva, he says. So if a sensor could be modified to react to those markers, it potentially could help dentists identify problems early on and refer patients to a physician before a condition becomes serious.

“The mouth is a window to the rest of the body,” Kugel says. “You can spot a lot of potential health problems through saliva, and it’s a much less invasive way to do diagnostic tests than drawing blood.”

Before monitoring of any type can take place, there is at least one major hurdle still be overcome. Humans are quite sensitive to objects being placed in their mouths. According to one of the researchers, we can sense objects that are 50 to 60 microns wide, about the thickness piece of paper, and that may be too uncomfortable to bear.

H/T Nov. 9, 2012 news item on Nanowerk for pointing me towards the latest information about these tooth tattoos.

Microneedles from Tufts University

Here’s some very exciting news from Tufts University in a Dec. 21, 2011 news item on Nanowerk,

Bioengineers at Tufts University School of Engineering have developed a new silk-based microneedle system able to deliver precise amounts of drugs over time and without need for refrigeration. The tiny needles can be fabricated under normal temperature and pressure and from water, so they can be loaded with sensitive biochemical compounds and maintain their activity prior to use. They are also biodegradable and biocompatible.

I have previously written about a micro needle project at the Georgia Institute of Technology in Nov. 9, 2011 posting and about Mark Kendall’s nano vaccine patch on more than one occasion, most recently in my Aug. 3, 2011 posting.

This new drug delivery project surprised me; I didn’t realize that horesradish could also be a drug,

The Tufts researchers successfully demonstrated the ability of the silk microneedles to deliver a large-molecule, enzymatic model drug, horseradish peroxidase (HRP), at controlled rates while maintaining bioactivity. In addition, silk microneedles loaded with tetracycline were found to inhibit the growth of Staphylococcus aureus, demonstrating the potential of the microneedles to prevent local infections while also delivering therapeutics.

“By adjusting the post-processing conditions of the silk protein and varying the drying time of the silk protein, we were able to precisely control the drug release rates in laboratory experiments,” said Fiorenzo Omenetto, Ph.D., senior author on the paper. “The new system addresses long-standing drug delivery challenges, and we believe that the technology could also be applied to other biological storage applications.”

If we’re all lucky, it won’t be too long before syringes are a museum item and we’ll be getting our medication with far less discomfort/pain and, in some cases, fear.

Bee silk; minnows and silver nanoparticles; David Cramb at U of Calgary finds way to measure nanoparticles in bloodstream; Rock Against Prisons

I had not realized that there’s an international drive to produce artificial insect silk until this morning. According to a news item on Nanowerk,

CSIRO [Australia's Commonwealth Scientific and Industrial Research Organisation] scientist Dr Tara Sutherland and her team have achieved another important milestone in the international quest to artificially produce insect silk. They have hand-drawn fine threads of honeybee silk from a ‘soup’ of silk proteins that they had produced transgenically.

These threads were as strong as threads drawn from the honeybee silk gland, a significant step towards development of coiled coil silk biomaterials.

“It means that we can now seriously consider the uses to which these biomimetic materials can be put,” Dr Sutherland said.

“We used recombinant cells of bacterium E. coli to produce the silk proteins which, under the right conditions, self-assembled into similar structures to those in honeybee silk.

If I understand this rightly,  ‘tinkering’ with bacterium E. coli makes this a transgenic system and I believe it’s a GEO (genetically engineered organism) and not a GMO (genetically modified organism). In any event, it’s also biomimetic because this process mimics a biological system.

On the practical side of things, insect silk could potentially be used for tough, lightweight textiles and medical applications such as sutures. You can read more about this in the Nanowerk news item.

A Purdue University study has added more evidence that silver nanoparticles are toxic to fish. According to the news item on physorg.com,

Tested on fathead minnows ╨ an organism often used to test the effects of toxicity on aquatic life — nanosilver suspended in solution proved toxic and even lethal to the minnows. When the nanosilver was allowed to settle, the solution became several times less toxic but still caused malformations in the minnows.

“Silver nitrate is a lot more toxic than nanosilver, but when nanosilver was sonicated, or suspended, its toxicity increased tenfold,” said Maria Sepulveda, an assistant professor of forestry and natural resources whose findings were published in the journal Ecotoxicology. “There is reason to be concerned.”

Coincidentally, Dr. David Cramb, director of the Nanoscience Program and professor in the department of Chemistry at the University of Calgary, and his colleagues have published a paper about a new methodology they are developing to measure the impact of nanoparticles (no specifics about which ones) on human health and the environment. From the news release on Eureka Alert, [Mar.4.10 ETA since I think the Eureka doesn't last long, here's a link to the same news on Azonano]

Cramb, director of the Faculty of Science’s nanoscience program, and his researchers have developed a methodology to measure various aspects of nanoparticles in the blood stream of chicken embryos. Their discovery is published in the March online edition of Chemical Physics Letters.

“With the boom in nanomaterials production there is an increasing possibility of environmental and/or human exposure. Thus there is a need to investigate their potential detrimental effects,” says Cramb. “We have developed very specialized tools to begin measuring such impacts.”

To close today off, I got a news release from poet Heather Haley (Vancouver, Canada based) about her latest local appearance,

Heather Haley was a member of Vancouver punk bands, the all-girl Zellots and the .45s with Randy Rampage and Brad Kent. Long-lost video of the Zellots will be screened and Heather will interviewed for a live webcast. She will perform poetry from her new collection, “Three Blocks West of Wonderland.” Hope to *see* you there.

ROCK AGAINST PRISONS Live Video Retrospective         Tuesday, March 9, 2010         7:00pm – 11:55pm
Little Mountain Gallery         195 east 26th Ave         Vancouver, BC
On March 9th, the social forces will be mounting an assault on the staid and the bland. From a Punk Rock Swap Meet to a Celebrity Auction, from an ‘umplugged’ stage to a Grand Slam Poetry Karaoke by some of the big stars of 1979, we are getting the Old Gang Together. We review the fabulous footage by doreen grey from the seminal 1979 gig and plan out the 2010 resurgence of the Vancouver Explosion.
Come on out and celebrate Vancouver’s living heritage with those who made it happen: Rabid, Female Hands, Devices, Zellots, Tunnel Canary, AKA, Subhumans. Special appearances. Door Prizes. Live Webcast and Kissing Booth. Fishnet stockings. Oodles of prime swag and fixins. Your every 1979 Punk nightmare come beautifully true.

You can also check out Heather’s latest work on her website.