Tag Archives: adhesive properties

Gluing a broken heart back together

The Jan. 8, 2014 news item on ScienceDaily doesn’t identify which creature(s) may have inspired the heart glue developed by researchers from Brigham and Women’s Hospital (BWH), Boston Children’s Hospital, and Massachusetts Institute of Technology (MIT),

When a child is born with a heart defect such as a hole in the heart, the highly invasive therapies are challenging due to an inability to quickly and safely secure devices inside the heart. Sutures take too much time to stitch and can cause stress on fragile heart tissue, and currently available clinical adhesives are either too toxic or tend to lose their sticking power in the presence of blood or under dynamic conditions, such as in a beating heart.

“About 40,000 babies are born with congenital heart defects in the United States annually, and those that require treatment are plagued with multiple surgeries to deliver or replace non-degradable implants that do not grow with young patients,” says Jeffrey Karp, PhD, Division of Biomedical Engineering, BWH Department of Medicine, co-senior study author of a new study that may improve how surgeons treat congenital heart defects.

In the preclinical study, researchers from Boston Children’s Hospital, BWH and Massachusetts Institute of Technology (MIT) developed a bio-inspired adhesive that could rapidly attach biodegradable patches inside a beating heart — in the exact place where congenital holes in the heart occur, such as with ventricular heart defects.

The Jan. 8, 2014 BWH news release on EurekAlert, which originated the news item, discusses the use of adhesives for repair in the body and some of the specifics of this particular application,

Recognizing that many creatures in nature have secretions that are viscous and repel water, enabling them to attach under wet and dynamic conditions, the researchers developed a material with these properties that also is biodegradable, elastic and biocompatible. According to the study authors, the degradable patches secured with the glue remained attached even at increased heart rates and blood pressure.

“This adhesive platform addresses all of the drawbacks of previous systems in that it works in the presence of blood and moving structures,” says Pedro del Nido, MD, Chief of Cardiac Surgery, Boston Children’s Hospital, co-senior study author. “It should provide the physician with a completely new, much simpler technology and a new paradigm for tissue reconstruction to improve the quality of life of patients following surgical procedures.”

Unlike current surgical adhesives, this new adhesive maintains very strong sticking power when in the presence of blood, and even in active environments.

“This study demonstrated that the adhesive was strong enough to hold tissue and patches onto the heart equivalent to suturing,” says the study’s co-first author Nora Lang, MD, Department of Cardiac Surgery, Boston Children’s Hospital. “Also, the adhesive patch is biodegradable and biocompatible, so nothing foreign or toxic stays in the bodies of these patients.”

Importantly, its adhesive abilities are activated with ultraviolent (UV) light, providing an on-demand, anti-bleeding seal within five seconds of UV light application when applied to high-pressure large blood vessels and cardiac wall defects.

“When we attached patches coated with our adhesive to the walls of a beating heart, the patches remained despite the high pressures of blood flowing through the heart and blood vessels,” says Maria N. Pereira, PhD, Division of Biomedical Engineering, BWH Department of Medicine, co-first study author.

The researchers note that their waterproof, light-activated adhesive will be useful in reducing the invasiveness of surgical procedures, as well as operating times, in addition to improving heart surgery outcomes.

As to which creature(s) may have inspired the glue, perhaps this offers a hint,

The adhesive technology (and other related platforms) has been licensed to a start-up company, Gecko Biomedical, based in Paris. [emphasis mine] The company has raised 8 million Euros in their recently announced Series A financing round and expects to bring the adhesive to the market within two to three years.

The last time geckos and adhesives were mentioned here was in a Jan. 2, 2014 posting titled: Simon Fraser University’s (Canada) gecko-type robots and the European Space Agency.

Getting back to the heart glue, here’s an image illustrating the researchers’ work,

Caption: The waterproof, light-activated glue developed by researchers at Brigham and Women's Hospital, Boston Children's Hospital and Massachusetts Institute of Technology can successfully secure biodegradable patches to seal holes in a beating heart. Credit: Karp Laboratory

Caption: The waterproof, light-activated glue developed by researchers at Brigham and Women’s Hospital, Boston Children’s Hospital and Massachusetts Institute of Technology can successfully secure biodegradable patches to seal holes in a beating heart.
Credit: Karp Laboratory

For the interested, here’s a link to and a citation for the paper,

A Blood-Resistant Surgical Glue for Minimally Invasive Repair of Vessels and Heart Defects by Nora Lang, Maria J. Pereira, Yuhan Lee, Ingeborg Friehs, Nikolay V. Vasilyev, Eric N. Feins, Klemens Ablasser, Eoin D. O’Cearbhaill, Chenjie Xu, Assunta Fabozzo, Robert Padera, Steve Wasserman, Franz Freudenthal, Lino S. Ferreira, Robert Langer, Jeffrey M. Karp, and Pedro J. del Nido. Sci Transl Med 8 January 2014: Vol. 6, Issue 218, p. 218ra6 Sci. Transl. Med. DOI: 10.1126/scitranslmed.3006557

This paper is behind a paywall.

Gluing blood vessels with mussel goo

The University of British Columbia [UBC] Dec. 11, 2012 news release states,

A University of British Columbia researcher has helped create a gel – based on the mussel’s knack for clinging to rocks, piers and boat hulls – that can be painted onto the walls of blood vessels and stay put, forming a protective barrier with potentially life-saving implications.

Co-invented by Assistant Professor Christian Kastrup while a postdoctoral student at the Massachusetts Institute of Technology, the gel is similar to the amino acid that enables mussels to resist the power of churning water. The variant that Kastrup and his collaborators created, described in the current issue of the online journal PNAS [Proceeings of the National Academy of Sciences of the US] Early Edition, can withstand the flow of blood through arteries and veins.

Here’s the citation and a link to the article (which is behind a paywall),

Painting blood vessels and atherosclerotic plaques with an adhesive drug depot by Christian J. Kastrup, Matthias Nahrendorf, Jose Luiz Figueiredo, Haeshin Lee, Swetha Kambhampati, Timothy Lee, Seung-Woo Cho, Rostic Gorbatov, Yoshiko Iwamoto, Tram T. Dang, Partha Dutta, Ju Hun Yeon, Hao Cheng, Christopher D. Pritchard, Arturo J. Vegas, Cory D. Siegel, Samantha MacDougall, Michael Okonkwo, Anh Thai, James R. Stone, Arthur J. Coury, Ralph Weissleder, Robert Langer, and Daniel G. Anderson.  PNAS, December 11, 2012 DOI: 10.1073/pnas.1217972110

For those of a more technical turn of mind, here’s the abstract (from PNAS),

The treatment of diseased vasculature remains challenging, in part because of the difficulty in implanting drug-eluting devices without subjecting vessels to damaging mechanical forces. Implanting materials using adhesive forces could overcome this challenge, but materials have previously not been shown to durably adhere to intact endothelium under blood flow. Marine mussels secrete strong underwater adhesives that have been mimicked in synthetic systems. Here we develop a drug-eluting bioadhesive gel that can be locally and durably glued onto the inside surface of blood vessels. In a mouse model of atherosclerosis, inflamed plaques treated with steroid-eluting adhesive gels had reduced macrophage content and developed protective fibrous caps covering the plaque core. Treatment also lowered plasma cytokine levels and biomarkers of inflammation in the plaque. The drug-eluting devices developed here provide a general strategy for implanting therapeutics in the vasculature using adhesive forces and could potentially be used to stabilize rupture-prone plaques.

The news release describes the work layperson’s terms,

The gel’s “sheer strength” could shore up weakened vessel walls at risk of rupturing – much like the way putty can fill in dents in a wall, says Kastrup, a member of the Department of Biochemistry and Molecular Biology and the Michael Smith Laboratories.

By forming a stable barrier between blood and the vessel walls, the gel could also prevent the inflammation that typically occurs when a stent is inserted to widen a narrowed artery or vein; that inflammation often counteracts the opening of the vessel that the stent was intended to achieve.

The widest potential application would be preventing the rupture of blood vessel plaque. When a plaque ruptures, the resulting clot can block blood flow to the heart (triggering a heart attack) or the brain (triggering a stroke). Mice treated with a combination of the gel and an anti-inflammatory steroid had more stable plaque than a control group of untreated mice.

“By mimicking the mussel’s ability to cling to objects, we created a substance that stays in place in a very dynamic environment with high flow velocities,” says Kastrup, a member of UBC’s Centre for Blood Research.

Robert Langer, one of the paper’s co-authors, was mentioned here in an Aug. 27, 2012 posting about nanoelectronics, tissue engineering, and medicine.

How do you make a harness for a gecko?

It’s the first question (how do you make a harness for a gecko?) I had on reading the latest research about geckos and their ability to adhere to various surfaces, dry and wet. From the Aug. 9,2012 news item on Nanowerk,

But first they had to find out how well their geckos clung onto glass with dry feet. Fitting a tiny harness around the lizard’s pelvis and gently lowering the animal onto a plate of smooth glass, Stark [Alyssa Stark] and Sullivan [Timothy Sullivan] allowed the animal to become well attached before connecting the harness to a tiny motor and gently pull the lizard until it came unstuck. [emphasis mine] The geckos hung on tenaciously, and only came unstuck at forces of around 20N, which is about 20 times their own body weight. ‘The gecko attachment system is over-designed’, says Stark.

Here’s more about the research and the geckos (from the news item),

Geckos are remarkable little creatures, clinging to almost any dry surface, and Alyssa Stark, from the University of Akron, USA, explains that they appear to be equally happy scampering through tropical rainforest canopies as they are in urban settings. ‘A lot of work is done on geckos that looks at the very small adhesive structures on their toes to really understand how the system works at the most basic level’, says Stark. She adds that the animals grip surfaces with microscopic hairs on the soles of their feet that make close enough contact to be attracted to the surface by the minute van der Waals forces between atoms. However, she and her colleagues Timothy Sullivan and Peter Niewiarowski were curious about how the lizards cope on surfaces in their natural habitat.

Explaining that previous studies had focused on the reptiles clinging to artificial dry surfaces, Stark says ‘We know they are in tropical environments that probably have a lot of rain and it’s not like the geckos fall out of the trees when it’s wet’. Yet, the animals do seem to have trouble getting a grip on smooth wet surfaces, sliding down wet vertical glass after a several steps even though minute patches of the animal’s adhesive structures do not slip under humid conditions on moist glass. The team decided to find out how Tokay geckos with wet feet cope on wet and dry surfaces, and publish their discovery that geckos struggle to remain attached as their feet get wetter in The Journal of Experimental Biology (“The effect of surface water and wetting on gecko adhesion” [behind a paywall]).

According to the news item, Tokay geclos were used for this study. These are neither small, nor amiable geckos according to the webpage devoted to Tokay Geckos on the anapsid.org website,

Native to SE Asia, these relatively large (12″) geckos are pale gray with bluish spots when they have been in the dark, darkening to dark gray with reddish spots in the light. Like most geckos, tokays are oviparous insectivores.

Young are 2-3″ at hatching. Eggs are laid in rocky crevices or under the eaves of houses. The 2-3 eggs, laid several times a year, are sticky and adhere to surfaces. In captivity, they may be laid on the glass sides of their terraria. Incubation time for the eggs ranges from 2-6 months for the oviparous Gekko species.

Tokays have the specialized lamellae on the pads of their toes which enable them to walk on vertical surfaces, including ceilings. Contrary to popular misconception, these pads are not “sticky” but rather are composed of tiny, microscopic filaments which find equally tiny imperfections in surface – including glass.

Like many lizards, tokays can darken or lighten their ground and spot colors to better blend in with their background.

Despite the fact that they follow human habitation, finding human dwellings to be great places to find prey, Tokays are the least lovable of the geckos. They are known for their nasty temperament, cheerfully biting the hand that feeds, cleans or otherwise comes into anything resembling close proximity to them. Their bites are powerful–one might say they are the pit bulls of the gecko world…they hang on and let go only when it suits them. Equipped as they are with numerous sharp teeth, the bites can bleed profusely and, even barring subsequent infection, are annoying for days. Note that while I am a strong believer that almost any animal can be habituated to human contact, such contact can be stressful for many species, and geckos as a whole are known for their marked preference to be left alone.

That harness question gets a lot more interesting after you’ve read about the Tokay Geckos, yes? I found the parts about being “the least lovable of the geckos’ and being known for their nasty bites particularly interesting.

Kathryn Knight’s article about the study for the Journal of Experimental Biology (which originated the news item) offers details about the testing on wet surfaces  (but no more about the harnesses),

Next, the trio sprayed the glass plate with a mist of water and retested the lizards, but this time the animals had problems holding tight: the attachment force varied each time they took a step. The droplets were interfering with the lizards’ attachment mechanism, but it wasn’t clear how. And when the team immersed the geckos in a bath of room temperature water with a smooth glass bottom, the animals were completely unable to anchor themselves to the smooth surface. ‘The toes are superhydrophobic [water repellent]’, explains Stark, who could see a silvery bubble of air around their toes, but they were unable to displace the water surrounding their feet to make the tight van der Waals contacts that usually keep the geckos in place.

Then, the team tested the lizard’s adhesive forces on the dry surface when their feet had been soaking for 90 min and found that the lizards could barely hold on, detaching when they were pulled with a force roughly equalling their own weight. ‘That might be the sliding behaviour that we see when the geckos climb vertically up misted glass’, says Stark. So, geckos climbing on wet surfaces with damp feet are constantly on the verge of slipping and Stark adds that when the soggy lizards were faced with the misted and immersed horizontal surfaces, they slipped as soon as the rig started pulling.

Therefore geckos can walk on wet surfaces, so long as their feet are reasonably dry. However, as soon as their feet get wet, they are barely able to hang on and the team is keen to understand how long it takes geckos to recover from a drenching.

Given the number of studies using geckos, I wonder if there are specialists devoted to creating gecko harnesses. In any case, one certainly can appreciate that the practice of science can sometimes be a blood sport. I think the question being asked is intriguing and it’s the first time I’ve seen any study of the gecko’s adhesive qualities being tested on wet surfaces.

Nano activities for the summer months

Courtesy of the July 2010 NISE (Nanoscale Informal Science Education) Net (work) newsletter, I have a list of nano-related activities taking place in various science museums and centres in the US. From the newsletter,

  • The Sciencenter in Ithaca, NY is integrating two mornings of nano programming into every two-week camp session. Sciencenter camp activities are designed for girls and boys entering grades 2 – 6 in the fall of 2010. Sciencenter educators plan an assortment of active, physical games, focused classroom experiences, special presentations, and free exploration of the museum and the science park. More information can be found at http://www.sciencenter.org/programs/sciencentersummercamp.asp
  • The Children’s Museum of Science and Technology (CMOST) in Troy, NY is partnering with the College of Nanoscale Science and Engineering to offer two week long sessions of Nano Camp! One week will be all inclusive, and the second week is a ladies-only GIST (Girls in Science and Technology) program. More information can be found at http://www.cmost.org/programs/summer_gist.php
  • The Arts and Science Center in Pine Bluff, AR held a weeklong nano camp in early June using some of the NanoDays kit activities.
  • The Museum of Science in Boston, MA is hosting its fourth round of science communication workshops for NSF-funded REU (Research Experience for Undergraduate) students from Boston-area nano research centers, and is working with the Discovery Center Museum and the UW Madison NSEC and MRSEC to adapt this set of workshops for integration into their REU programs. The goal of these workshops is to help to cultivate a new generation of nano and materials science researchers aware of the broader context of their research and equipped with the skills to communicate effectively on interdisciplinary research teams and to engage broader audiences.[emphases mine]
  • In about a month, the National Nanotechnology Infrastructure Network (NNIN) REU will gather at the University of Minnesota for their network-wide convocation.  All 80 NNIN REU interns will present a talk and a poster.  Plus, all 18 International REUs, the iREUs, will be attending having just gotten home from Belgium, Germany or Japan!  Finally, staff from every site, along with many of the interns’ parents and friends, attend.  It’s an exciting event where staff and interns meet and find out what everyone has been up to over the summer. The presentations are web-cast and details and schedules can be found at http://www.nano.umn.edu/nninreuconvocation2010/.
  • The Summer Institute for Physics Teachers is currently going on at Cornell’s Center for Nanoscale Systems. The course, open to high school physics teachers, includes lectures are given by Dr. Julie Nucci and many Cornell faculty on topics such as electronics, photonics, nanotechnology, and particle physics. Lab tours provide a glimpse into state-of-the-art academic research.  The lab activities, which are co-developed by high school physics teachers and Cornell scientists, are presented by teachers.

I highlighted the science communication workshops for the US undergraduates in light of a recent (July 8, 2010) University of British Columbia media release announcing two recent federal grants including this one,

young researchers at UBC were awarded a further $1.6 million from the Collaborative Research and Training Experience (CREATE) program to help upgrade their skills for a successful transition to the workplace.

The CREATE grant to UBC is part of a $32-million investment over six years from NSERC, for 20 projects at Canadian universities. The funding will give science and engineering graduates an opportunity to expand their professional and personal skills to prepare them for the workplace.

While the two programmes are markedly different, the fact of their existence is intriguing. I don’t believe communication skills workshops or programmes to upgrade workplace skills for budding young scientists have been a feature of science training (in Canada anyway) until fairly recently. If you know differently, please do comment.

I’ve long been interested in the work being done on adhesive forces (usually Spiderman or geckos are featured in the headline for the news release) so I was quite happy to see this in the newsletter,

→ Geckos!

Check out our new program Biomimicry: Synthetic Gecko Tape through Nanomolding.  The hands-on activity gives visitors a glimpse of one of the methods used by researchers to make synthetic gecko tape.  Visitors make their own synthetic gecko tape with micron-sized hairs that mimic the behavior of the gecko foot and test how much weight their gecko tape can hold using LEGOs. The activity was designed to fit into a classroom/camp program, but can be adapted for a museum floor.

If the scientists are successful, it means you won’t need glue to stick things together, for example, putting up curtain rods. (Some curtain rods use adhesive pads so you can pull them on and off the walls but if you do that too many times you lose the adhesive properties; Spiderman and geckos don’t experience that problem.)

I found the document which tells you exactly how to create your synthetic gecko tape. You may not have the materials needed easily available but if you’re interested, the instructions are here.

This month’s nano haiku,

Surface to Volume
new science with a nano
Golden Ratio

by Luke Doney of the Museum of Nature and Science in Dallas, TX

If you want to check NISE Net, go here.