BOSTON, Mass. (Ivanhoe Newswire) – What do a spider, porcupine, and worm all have in common? The answer, they’re allowing researchers to develop a new medical tape that’s super sticky and doesn’t damage the skin.
It’s a new neonatal medical tape that unlike old tape doesn’t tear the tender skin of babies. Jeffery Karp, associate professor at Harvard Medical School and Brigham and Women's Hospital, used geometry from the spider's web and added a third layer to the bandage.
“We changed the point where the bandage breaks to a middle layer,” Karp told Ivanhoe.
The Spiny Headed Worm helps Karp’s team create a microneedle adhesive patch to help keep skin grafts in place. Inspired by a parasite worm feeding off fish, scientists designed these needles to grab onto the skin, swell up, and lock in.
“There's a greater chance of engraftment, so less complications and less number of procedures,” Karp explained.
Porcupine quills, because of their geometry and backward facing barbs, allow for easier penetration than standard needles.
“When a clinician is pushing a needle, for example, into tissue, if they have to push harder on the needle there is a greater chance of overshooting the injuries,” Karp said.
Karp’s team believes the biomedical patch could someday deliver medicine to patients. So far, this tape has not gone through human clinical trials.
Jeffrey Michael Karp, Ph.D, Associate Professor of Medicine at Brigham and Women’s Hospital at Harvard Medical School, talks about how nature is inspiring a new medical procedure.
You are doing a bunch of different things in this lab; you are working on something called the Worm Adhesive. What is the Worm Adhesive?
Dr. Karp: We were very inspired by parasites. Parasites have really interesting ways of colonizing their hosts and they are able to latch on and essentially survive by interacting with their host for long periods of time. When we started thinking that maybe there is some unique examples in nature of parasites and their ability to attach to creatures we started looking to see what we could find. We identified that there was a type of worm called the spiny-headed worm that has this needle like structure. The spiny-headed worm pushes into the intestine of fish and then only the tip part expands. Through this expansion it is able to latch on and really grab onto its host. We were very inspired by observing this in nature and we thought this could serve as a really great example for solving some problems that exist in medicine For example, we are still using the same methods for tissue fixation, such as staples and suture that we have been using for decades and decades and these have substantial drawbacks. So we were interested in developing an adhesive that could achieve very strong levels of adhesion, but could around some of the previous problems that are experienced with sutures and staples in the operating room.
How far along are you with this?
Dr. Karp: We have developed these adhesives and we have tested them in a number of relevant scenarios. For example, we were able to show that we could affix skin grafts to underlying tissue. One of the problems is that in the clinic, staples are currently used and the staples are placed at the periphery of the skin graft, so if any fluid accumulates between the graft and the underlying tissue, it can cause seroma and the graft simply won’t take. There are a lot of complications associated with that. What we were able to show is that we could take our micro needle adhesive; place it onto the skin graft, which we were able to secure it in place to the underlying tissue, and we had 100% surface area of contact; so intimate contact between the graft and the tissue and then it took 3-1/2 times more force to remove the graft when we use our microneedle adhesive technology compared to the standard staples.
What is the benefit to the patient?
Dr. Karp: The benefit to the patient is that there is a greater chance for engraftment; so less complications; less number of procedures that the surgeon will have to perform to replace the grafts. These micro needles that have swellable tips can be used to deliver drugs. We can deliver antibiotics to prevent infection. We can deliver agents that could accelerate the wound healing process that could enable patients to go home quicker.
What type of procedure would you use the worm adhesive on?
Dr. Karp: We focused some of our testing on application for skin grafts, but we do think that this could be used in minimally invasive procedures as well as many others.
Then you have something else that was inspired by the porcupine. Tell me about that.
Dr. Karp: Porcupines are really interesting creatures. They have quills on their backs that insert into tissue very easily, but are extremely difficult to remove. We spent about four years trying to elucidate the mechanism of porcupine quills, in particular the North American porcupine, and so porcupine quills, look like needles, but they have these backwards facing barbs that point away from the tip. What we discovered is that not only do the barbs significantly increase the level of adhesion, but what they also do is they significantly reduce the force required to push this into tissue. This is really exciting because when a clinician is pushing a needle for example into tissue, if they have to push harder on the needle, there is a greater chance of overshoot injury. So they have less sensitivity of getting that needle to the right location. If we can reduce the amount of force required to push a needle into tissue this could lead to a major advance to reduce complications in the clinic. In addition to this we created a bio-inspired synthetic porcupine quill patch.
Synthetic quills that’s amazing; how were you able to accomplish this?
Dr. Karp: We made plastic quills that mimicked the natural quills precisely. We were able to show that we could very easily push these adhesive patches into tissue, but they were difficult to remove. We think that this could really be useful for replacing sutures or staples or even for example as a hernia mesh. Patients who have hernias often have a mesh that is placed at the site and one of the challenges is that the tacks that are used are pushed really far into the tissue and they can hit blood vessels or nerves and cause a lot of complications. The nice thing about the porcupine quills is that you do not really need to push them very far into the tissue to achieve significant levels of adhesion. We think that a porcupine quill-inspired adhesive could be broadly applicable for many medical applications.
Where is it currently in development?
Dr. Karp: We have been able to show that we can achieve significant levels of adhesion with multiple types of tissue. We have looked at intestine tissue; we have looked at skin; we have looked at heart tissue and other tissues as well. Now what we are in the process of doing is setting up some preclinical studies that will allow us to kind of tweak the system to maximize the potential success of this platform and once we are able to show that we can achieve a significant improvement over current adhesives, we will be able to move this to the clinic.
What is the goal with the porcupines? What are you hoping for?
Dr. Karp: The major goal here is that we are developing technologies to solve medical problems. What we like to do is step out of the conventional thought process, that we get into, in the laboratory and we like to go into nature and look for inspiration.
You are also working on a spider web inspired neonatal adhesive, tell me about that.
Dr. Karp: The Institute for Pediatric Innovation, in Boston, did a needs assessment where they went to many of the neonate units across the United States. When they interviewed doctors and nurses, they identified that the biggest problem in neonate units is applying adhesives to the skin of neonates; their skin is very fragile. They do not have a mature epidermis, which is the top layer of skin and the idea is you want to be able to affix devices to monitor temperature or heart rate, but the problem is that when you remove these devices, they tear the skin, because these tapes were designed for adult skin, not for neonate skin. So we developed a next generation adhesive that could secure tubes or other devices to the fragile skin of neonates, but could be removed with 10x less force. When these adhesives are removed they do no damage.
Where are you in the process of that?
Dr. Karp: This was a project that was sponsored by a company, Phillips. Phillips is very interested in helping to advance this to patients.
What are you using to make the adhesive?
Dr. Karp: One of the key design criteria when developing this next generation neonatal adhesive was to use materials that already existed in the current tapes that were used in the neonate units. So we did not change any of the materials, we just found a new way to formulate those materials that was inspired by nature. For example, in nature spider webs have very sticky regions as well as regions that are not so sticky. What that enables is that the spider web can capture prey on the sticky regions, but the spider is able to walk across its web on the non-sticky regions. So we made use of this concept in this neonatal adhesive.
What did you do?
Dr. Karp: Most adhesives have two layers, a backing layer, which is what you see when the bandage is on your skin and an underlying adhesive, which essentially glues the backing to your skin. The problem with that is when you remove it, what typically happens with adult skin is that the adhesive breaks; that is why when we remove a bandage, we have some glue leftover on our skin. For the neonates the weakest point is in their skin; so it just tears their skin. What we did is we changed the point where the bandage breaks to a middle layer; we introduced a third layer in between the backing and the adhesive. We patterned this layer with adhesive and non-adhesive domains, just like that observed in a spider web so that we could control the interaction of the adhesive with the backing layer; that you could remove the backing from the underlying adhesive with minimal force.
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