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Biomedical Engineering

The Biomedical Engineering blog is the place for conversation and discussion about topics related to engineering principles of the medical field. Here, you'll find everything from discussions about emerging medical technologies to advances in medical research. The blog's owner, Chelsey H, is a graduate of Rensselaer Polytechnic Institute (RPI) with a degree in Biomedical Engineering.

Silk’s Not Just for Neckties

Posted June 13, 2016 1:34 PM by BestInShow

With so many novel advanced materials making news these days – like graphene in all its permutations – I was pleased to discover that silk, a material that dates back to ancient times, has many 21st-century uses. Researchers at Tufts University’s Silk Lab, at MIT, North Dakota State University, and elsewhere are contributing novel applications for silk proteins.

Where does silk come from?

Silk comes from silkworm spit. Doesn’t that just make you want to run out and buy a set of silk PJs? Seriously, if you ask most people where they think silk comes from, they’d answer it comes from the cocoons of mulberry silkworms (Bombyx mori) cultivated expressly for textiles. (And their cocoons are made of spit.) These cocoons produce the gold standard of textile silk because each one unreels into a single strand of silk. Longer fibers make superior fabric. Most silk comes from the larvae of cocoon-forming insects. However, other insects and, most notably, arachnids also produce silk fiber.

It’s more accurate to define silk as fibers composed predominately of fibroin, an insoluble protein, with sericin, a water-soluble, glue-like protein, coating the filaments. This definition includes all types of naturally-produced and manmade silk. Researchers typically separate the fibroin from the sericin and use the fibroin in their experiments.

Biomedical applications of silk

I got the idea for this blog when I read about Tufts University’s silk portfolio . Two researchers, biomedical engineer David Kaplan and physicist Fiorenzo Omenetto, have developed products ranging from edible optical sensors to multiple biomedical devices. Several qualities of silk – biocompatibility, manipulability, biodegradability, and sustainability – make it highly attractive to biomedical researchers. Silk is also “tunable;” researchers can fashion it into different forms for different purposes. Following are some products, from Tufts, MIT, and elsewhere, that showcase both silk’s qualities and the researchers’ out-of-the-box thinking.

The first silk-based biomedical product from Tufts is a long-term bioresorbable surgical mesh designed for the support and repair of weakened or damaged connective tissue. Pharmaceutical company Allergan bought Serica, the Tufts spinoff that developed this product, in 2010; Allergan continues to develop its potential.

Kaplan and the Tufts team combined fibroin with glycerol to create a self-curing 2D and 3D printer “ink” that can print body tissues and body parts. Previous attempts used thermoplastics and other materials that require heat curing, a process that damages some components. Fabricators can include antibiotics or other compounds with the silk-based ink.

Amanda Brooks, a North Dakota State University researcher, is developing spider silk hydrogels to deliver antibiotics directly to an infection. She tunes the tiny silk bubbles to recognize infection and act only on the infection, not on healthy tissues.

Omenetto’s lab – the Silk Lab at Tufts – and John Rogers of the University of Illinois at Urbana Champaign are exploiting silk’s compatibility with electronics to develop a wireless, remote-controlled, silk-based device referred to as a “magnesium heater,” and designed to kill a localized bacterial infection. When the heater has finished its work, it dissolves harmlessly in the patient.

Image from Tufts University

A brand-new non-medical oddball use for silk

Tufts silk specialists just published news of a method for keeping fruit fresh for at least a week without refrigeration, a technique that could significantly reduce waste incurred when transporting food to market. Fruit coated in a tasteless, odorless, nearly invisible coating of silk exploits silk’s biocompatibility and dissolvability in the human body.

… and an off-the-wall, way out-of-the-box use

MIT researchers led by Markus Buehler have discovered that the different levels of silk’s structure, specifically spider silk, correspond with “the hierarchical elements that make up a musical composition—individual notes assembled into measures, which in turn form a melody, and so on.”

Working with composer John McDonald, a professor of music at Tufts, and MIT postdoc David Spivak, a mathematician who specializes in category theory, Buehler discovered that “strong but useless” protein molecules produced aggressive music, and useful fibers produced softer music. “This taught us that it’s not sufficient to consider the properties of the protein molecules [when designing a molecule] alone,” Buehler says. It’s also necessary to “think about how they can combine to form a well-connected network at a larger scale.”

A wonder material?

Tufts’ Omenetto believes that, while silk might be a wonder material, science should take a broader view. One of the reasons he and others like working with silk is the low impact silk processing and use has on biological systems and the environment. He’d like to see science seek other substances that share this combination of function and low impact. In the meantime, he and other researchers continue to exploit silk’s advantages.

References

https://en.wikipedia.org/wiki/Silk

http://live-sciencefriday.pantheonsite.io/videos/the-medical-wonders-of-worm-spit-2/

http://spectrum.ieee.org/tech-talk/biomedical/devices/silkbased-implants-fight-bacterial-infection-then-vanish-

Image credit:

Wikipedia

3 comments; last comment on 06/14/2016
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When You Should Swear

Posted May 15, 2016 12:00 AM by Chelsey H

Everyone has the same reaction when they stub their toe on the edge of the bed. And now we know why it makes you feel…better.

A phenomenon known as lalochezia allows us to tolerate more discomfort for a longer period of time when we swear. There is something exciting about swearing because swear words come from taboo topics. It's also linked to an emotion which sparks a biological response in our bodies to help us tolerate pain.

You can't stock up on swear words though: the more you swear the less it helps.

Learn more by watching this video!

14 comments; last comment on 06/14/2016
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Revolutionary Regeneration

Posted May 03, 2016 2:02 PM by Chelsey H

Have you ever seen a gecko regrow its tail? The regeneration of limbs by salamanders and geckos was the inspiration for research done at UNSW Australia. The research team identified stem cell therapies capable of regenerating any human tissue damaged by injury, disease or aging.

The research, published in Proceedings of the National Academy of Science journal, describes a process in which bone and fat cells are reprogramed to induced multipoint stem cells (iMS).

The ground-breaking technique switches off the memory of fat and bone cells and converts them into stem cells so they can repair different cell types once they are put back in the body. This is done by mixing the cells in a bath of 5-Azacytidine (AZA) and a platelet-derived growth factor. AZA is known to induce cell plasticity and helps "relax" the hard-wiring of the cell. The growth factor expands the cell transforming it into iMS cells. When the stem cells are inserted into the damaged tissues site, they multiply, promoting growth and healing.

Salamander limb regeneration also depends on the plasticity of differentiated cells. Image Credit

The technique has been successfully demonstrated in mice and human trials are expected to start in late 2017. Dr Ralph Mobbs, Neurosurgeon and Conjoint Lecturer with UNSW's Prince of Wales Clinical School, will lead the trials.

"The therapy has enormous potential for treating back and neck pain, spinal disc injury, joint and muscle degeneration and could also speed up recovery following complex surgeries where bones and joints need to integrate with the body," Dr Mobbs said.

5 comments; last comment on 05/05/2016
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Did You Inherit Your Sweet Tooth?

Posted April 19, 2016 12:00 AM by Chelsey H

"No thanks, I'm not a dessert person."

I don't know about you, but not much else inspires me to hate someone as much as that statement does. Who doesn't like dessert?! Why are some people able to resist the bowl of Hershey Kisses on the conference table but they eat an entire bag of Sour Patch Kids in one sitting?

Scientist have discovered that some humans have genes that make them more sensitive to bitter compounds, suggesting that there might be differences in how the other four tastes - sweet, sour, salt, and umami - are genetically wired. Image credit

The study of perception of sweetness was done comparing identical and fraternal twins with non-twin siblings and unpaired twins. Twins are helpful for studying genetic factors since identical twins share almost all their genes and fraternal twins share about half.

The researchers at Monell Chemical Senses Center gave the twins and other subjects two natural sugars (glucose and fructose) and two artificial sweeteners (aspartame and NHDC) and then asked them to rate the perceived intensity of the solution.

The study found that a single set of genes account for about 30 percent of the variance in sweet taste perception between people for both natural and artificial sugars.

Much to my dismay (who doesn't want to blame genes for bad habits), the findings do not mean that people who have a weaker ability to taste sweet necessarily dislike sugar or vice versa. The researchers still need to see whether the results have implications on people's food behavior. This is a challenge to study because researchers rarely get an accurate picture of what a person eats every day.

Danielle Reed, the lead researcher for this study, says the variation in taste may have to do with the fact that humans evolved in so many different geographies and around so many different types of food.

These days, I would love to be more sensitive to sugar since it's found in everything and has become a serious health risk. But as I sit and enjoy a hot cocoa, I think I'll just wait for my genes to change. J

The full study appears in the journal Twin Research and Human Genetics.

4 comments; last comment on 04/20/2016
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Revolutionizing the Prosthetic Hand to Teach It New Tasks

Posted April 13, 2016 12:00 AM by Engineering360 eNewsletter

Engineers are working to develop a prosthetic hand that will give users a sense of feedback and a realistic sense of touch.

Read more.


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