Polymer Suture Methods Old and New

Gortex sutureJust like there are many ways to “skin a cat,” there are various ways to stitch his wounds as well. The use of polymers in sutures, as with many medical devices, is becoming more varied than ever before.

Reimagining PGLA

The newest way is with the use of nanofiber mats made up of the polymer poly(lactic-co-glycolic-acid) or PGLA. This method has been previously examined for sealing wounds; however, the technique had fallen away because of concerns about depositing the materials safely. The method currently used for creating the mats involves electrospinning, which uses electric currents and can damage tissue when the mats are created in situ.

Spray-On Healing

Researchers at the University of Maryland, College Park, found a way to deposit the nanofiber mats in a precise and efficient manner. The deposition is made by using a standard airbrushing machine that can be purchased at your local hardware store. When the fibers are airbrushed onto the target, they can take the shape of the area and promote healing.

Bioengineer Peter Kofinas explained that this type of material can be used as suture and may also be used for transporting biodegradable, controlled-release drug implants as well as tissue engineering scaffolds. The material was tested in the lab to seal cuts made to the lung, liver, and intestine. It also proved capable of closing a hernia in the diaphragm. Complete degradation was found to occur after 42 days.

The formulation was tweaked based on the airbrush technique until the researchers were content with their findings. Acetone was used as a solvent to control the thickness of the PGLA fibers. Optimal deposition was found using fibers with a diameter of 370 nm. Before depositing the polymeric mat, the acetone evaporated, leaving no toxic residue to interfere with wound healing.

‘Using an airbrush to deposit biomaterials directly onto tissue is quite enticing and has potential in many areas of medicine,’ says Jeffrey M. Karp, a bioengineer and co-director of the Center for Regenerative Therapeutics at Brigham & Women’s Hospital in Boston.

Traditional Sutures

Traditional sutures are made from biological sources like the Chromic suture and from polymers (for example, polyglactin 910). There are several different types of sutures: absorbable, non-absorbable, braided, and non-braided. They come in different-size diameters as well. It’s important to choose the proper suture, as each characteristic is important to the healing process of the particular wound. Absorbable sutures break down in the body. Non-absorbable sutures will be removed. If used inside the body, they will remain in the tissue. Braided tissue is a collection of filament strands woven together. Non-braided tissue consists of a single filament strand.

Absorbable surgical sutures are made from various materials and, depending on the materials, the absorption can take anywhere from 10 days to eight weeks. Synthetic suture materials are made from a variety of polymers, including polyglycolic acid, polylactic acid, and polydioxanone. Monocryl™ is made from poliglecaprone 25 (a copolymer of glycolide and epsilon-caprolactone) and is manufactured by Ethicon®. Catgut suture is the original absorbable suture. It is a sterile monofilament made from the connective tissue of beef or sheep intestines.

Non-absorbable sutures are made from many different materials depending on the application involved. Nylon, polyester, polyvinylidene fluoride (PVDF), polypropylene, and ultra-high molecular weight polyethylene (UHMWPE) are a few of the synthetic non-absorbable sutures. Gore-Tex® suture is also non-absorbable and composed of a proprietary expanded polytetrafluoroethylene (ePTFE). Steel suture is made from 316L stainless steel. Silk is the original non-absorbable suture material derived from an organic protein called fibroin.

Technological advancement has allowed the inclusion of 316L stainless steel staples to close wounds as well as surgical glue (cyanoacrylate). They both are fast and effective methods of suturing.

So the next time you’re in the emergency room and the doctor pulls out an airbrushing machine, don’t assume he’s going to start repainting the place. Just hold out your boo-boo and say “Ahhhhh.”

Image by Gore-Tex®
Source: “In Situ Deposition of PLGA Nanofibers via Solution Blow Spinning,” by Adam M. Behrens, et al., ACS Macro Letters, February 26, 2014, DOI: 10.1021/mz500049x
Source: “Spray-On Nanofibres Bind Surgical Wounds,” by Stephen Luntz, www.iflscience.com, March 29, 2014
Source: “Surgeons to Seal Incisions with Spray-On Polymer Mats,” www.nurseslabs.com, March, 29, 2014
Source: “Spray-On Polymer Mats Seal Surgical Incisions,” by Katherine Bourzac, www.cen.acs.org, March 24, 2014
Source: “Surgical suture,” wikipedia.org
Source: “Wound Closure – Sutures,” ethicon.com

Gold Medical Device Saves Money in Diabetes Testing

Glass "lab-on-a-chip."

A glass “lab-on-a-chip.” Stanford researcher have used a similar technology to create an inexpensive test for diabetes.

Thanks to nanotechnology, the “lab on a chip” is no longer a futuristic goal — it’s here and it’s now. Stanford University scientists have developed a new microchip using gold coatings to diagnose type-1 diabetes in patients. The chip uses nanotechnology to replace the current costly and underutilized detection method.

Most of us are under the impression that type-1 diabetes is a childhood disease and type-2 diabetes is the adult form of the disease. However, more adults are being diagnosed with type-1 diabetes than ever before. Moreover, due to the rate of childhood obesity in the U.S., more and more children and teenagers are being diagnosed with type-2 diabetes.

American Diabetes Association Figures

Here are the American Diabetes Association’s diabetes statistics for the U.S. (as of 3/2013):

  • Nearly 26 million children and adults have diabetes
  • 5% of patients have type-1 diabetes
  • 90%-95% of patients are diagnosed with type-2 diabetes
  • 79 million people are prediabetic
  • 1.9 million new cases are diagnosed with diabetes yearly
  • Current trends illustrate 1 in 3 adults will have diabetes by 2050
  • The cost of diagnosed diabetes per year is $245 billion
  • Diabetes kills more people per year than AIDS and breast cancer combined

Two Types of Diabetes

Insulin is a hormone produced by the pancreas that converts sugar, starches and other food into energy (as glucose) and helps transport it to the body’s cells. Insulin also regulates blood glucose levels in the body. Type-1 diabetes, also known as juvenile diabetes or insulin-dependent diabetes, is an auto-immune disease that occurs when the patient’s own antibodies destroy insulin-producing cells in the pancreas. Insulin production slows to a stop and the body can no longer control or carry glucose in the blood. This can lead to life-threatening complications if left undiagnosed.

Type-2 diabetes occurs when glucose levels rise to higher than normal (hyperglycemia). It’s also called insulin-resistant because the tissues that need insulin to absorb glucose become resistant to the presence of insulin. Consequently, the body overproduces insulin to try to regulate blood glucose levels. Over time, it becomes unable to make enough insulin to control excess blood sugar, leaving some individuals incapable of producing insulin at all.

Testing for Diabetes

The differences in the two types of diabetes call for accurate diagnosis of the disease and prompt, relevant treatment anything less could be detrimental to the health of the patient.

The current test to determine the patient’s diabetes type is a radioimmunoassay. It’s slow, expensive, requires highly trained technicians, and uses radioactivity to detect auto-antibodies. For these reasons, doctors don’t rely on the current methods of detection. They usually associate diabetes type-2 by the age, weight, and lifestyle of an adult patient. However, as discussed earlier, rates of adult patients with type-1 diabetes are on the rise.

The new chip is inexpensive, involves no radioactivity, requires little training to use and needs only a drop of blood from the patient. The technology behind the chip is fluorescence-based. Glass plates form the base of the chip and are coated with an array of gold nanoparticles. The gold helps to magnify the fluorescent signal aiding in the detection of the auto-antibodies associated with type-1 diabetes.

Auto-Antibodies Also Screened

This new diagnostic test can also detect auto-antibodies to screen for patients who are at risk for type-1 diabetes, for example, a direct relative of a type-1 diabetes patient. This will aid physicians in early treatment of patients who could potentially develop the disease to help prevent complications due to type-1 diabetes — or even prevent the disease entirely.

Senior author Brian Feldman, M.D., Ph.D., assistant professor of pediatric endocrinology, the Bechtel Endowed Faculty Scholar in Pediatric Translational Medicine, expressed his hopes:

With the new test, not only do we anticipate being able to diagnose diabetes more efficiently and more broadly, we will also understand diabetes better — both the natural history and how new therapies impact the body.

Feldman also works as a pediatric endocrinologist at Lucile Packard Children’s Hospital Stanford.

Stanford University and the scientists involved are in the process of patenting this novel medical device. A start-up company is in the works to help get FDA approval and get the device to market for use in the U.S. and globally.

“We would like this to be a technology that satisfies global need,” Feldman said.

Image by Micronit.
A Plasmonic Chip for Biomarker Discovery and Diagnosis of Type 1 Diabetes,” by Bo Zhang, Rajiv B Kumar, Honjie Dai, and Brian J Feldman, Nature Medicine, July 13, 2014, DOI: 10.1038/nm.3619.
Diabetes Diagnosed with Inexpensive, Portable Microchip Test,” by Catherine Paddock, Ph.D., Medical News Today, July 14, 2014.
Researchers Invent Nanotech Microchip to Diagnose Type-1 Diabetes,” by Erin Digitale, Stanford University News Center, July 13, 2014.
Coming Soon — Cheaper Nanotech Microchip to Diagnose Type-1 Diabetes,” thehealthsite.com, July 14, 2014.

Bubble Wrap Used as Polymer Labware

Familiar bubble wrap has found a new use as an inexpensive, polymer container for scientific analyses and experiments.

A team of scientists at Harvard University’s Department of Chemistry and Chemical Biology are looking at bubble wrap to pop a hole in traditional lab analysis requirements.

Bubble wrap is made from the resin form of a thermoplastic polymer called polyethylene and was originally intended as a new type of wallpaper. Its current and better known use is protecting our valuables from damage (and when that’s done, of course, driving people crazy in a frenzy of pop-pop-popping!)

Tiny Test Tubes

Now, researchers have found there may be a more important and productive use for this bubbly, plastic, de-stressing marvel. They proposed the use of bubble wrap as a sheet of tiny test tubes. According to their reports, tests can be done right inside the bubbles! The material needs to be handled gingerly when the bubbles are filled and ready for analysis. However, the idea has incredible potential when it comes to regions with limited or no resources to execute such analyses.

The material is cheap and available virtually everywhere. It’s flexible and doesn’t break like glass test tubes. The sterile bubbles were filled with liquids, for storage or analysis, by injecting them with a needle or pipette tip. The holes were sealed using a nail hardener. Bubble wrap is easily disposed of by burning, and since the bubbles are sterile inside, there is no need for an autoclave (or the electricity it takes to run one). This is an incredible advantage to the almost 2 billion people who don’t have access to electricity on a regular basis.

They are clear in the visible range like cuvettes, and can be used for absorbance and fluorescence measurements. They are gas-permeable, which allows them to be used for the storage and growth of microorganisms. Finally, carbon electrodes can be added so the bubbles can be used as electrochemical cells.

Applications

Glucose and hemoglobin were tested using a spectrophotometer, and ferrocyanide (a salt) was examined electrochemically. Using the bubble wrap, the scientists were able to culture E. coli — a very important factor in detecting contamination in water samples. They also were able to grow the microorganism C. elegans, a nonparasitic roundworm.

The ability to use something so commonly available and inexpensive for testing in developing areas is a wonderful contribution to science. For instance, carrying only lightweight materials, a soldier could test water for potability for his battalion in the middle of nowhere with limited resources.

Thought for the day: The next time you fly, you might want to be sure to pack some handy-dandy bubble wrap in your carry-on, just in case. Who knows? You may need it to bring a fragile souvenir back from your vacation. Or in a worst-case scenario, you’ll end up like the people on Lost, but at least you’ll have a leg up in the lab analysis department. That is, unless the passenger next to you finds it first and pops all your precious test tubes. In the off chance you end up like Tom Hanks in Castaway, you may want to bring along a Wilson volleyball too.

Image by maropictures/123RF.
Adaptive Use of Bubble Wrap for Storing Liquid Samples and Performing Anaytical Assays, Analytical Chemistry,” by David K. Bwambok, et al., Science, July 21, 2014, DOI: 10.1021/ac501206m.
Bubble Wrap Serves as Sheet of Tiny Test Tubes in Resource-Limited Regions,” Phys.org, July 16, 2014.
Bubble Wrap Can Make Great DIY Test Tubes,” by Rachel Nuwer, Smithsonianmag.com, July 18, 2014.

New Class of Recyclable Polymers Makes Debut

New-Polymer-Reinforced-with-Carbon-Nanotubes

A scanning electron microscopy (SEM) image of the new ultra-strong polymer reinforced with carbon nanotubes.

Imagine a future with “self-healing” car panels that can repair themselves after a minor scratch. Or imagine the cost savings (passed to the customer) made possible by more efficient microfabrication — the manufacturing costs of semiconductors, for example, would be slashed while retaining the enviable properties of being strong, lightweight, and even recyclable! All of these future applications could be possible very soon thanks to a new class of polymers discovered by IBM Research scientists. Innovation like this could affect everything from adhesives to airplane construction.

The researchers have found a new class of polymers, along with colleagues at the King Abdulaziz City for Science and Technology (KACST) in Riyadh, Saudi Arabia, the University of California at Berkeley, and Eindhoven University of Technology in the Netherlands.

Unique Properties

While a commercial name has yet to be revealed, the chemical name for these new polymers is hemiaminal dynamic covalent networks (HDCNs); when HDCNs are further cyclized at high temperatures, poly(hexahydrotriazine)s (PHTs) are produced. The unique properties of these new polymers include greater strength than bone, lightweight structure, resistance to cracking, resistance to solvents, and the ability to self-heal (morph back to original shape). They are 100% recyclable and, when used as a resin, can be a fill to reinforce composite material. Polymers with these properties are ideal for the transportation, aerospace and microelectronics industries and could transform their manufacturing and fabrication processes.

Materials used in the transportation and aerospace industries are exposed to harsh environmental conditions, which can lead to stress fractures within current materials, compromising strength. These materials generally are not recyclable because once cured, they cannot be restructured, so they are thrown out. In the field of microelectronics, parts and chips cannot be re-formed once they’ve been manufactured, so they are discarded if found to be defective they are discarded. Semiconductor materials are expensive and waste costs the manufacturer money.

Computer-Assisted Design

The last class of “new” polymers was introduced to the world decades ago. Most new discoveries were created using slow and methodical experimentation methods in the lab. Current research examines existing polymers by combining them with other known polymers or adjusting their functional groups to get a desired effect. A new process created by IBM uses cutting edge computing to determine novel polymer-forming reactions, taking much of the time and guesswork out of the equation.

James Hedrick, advanced organic materials scientist at IBM Research, said:

Although there has been significant work in high-performance materials, today’s engineered polymers still lack several fundamental attributes. New materials innovation is critical to addressing major global challenges, developing new products and emerging disruptive technologies [...] We’re now able to predict how molecules will respond to chemical reactions and build new polymer structures with significant guidance from computation that facilitates accelerated materials discovery. This is unique to IBM and allows us to address the complex needs of advanced materials for applications in transportation, microelectronic or advanced manufacturing.

These new polymers will remain undamaged when subjected to basic water (high pH), however, the polymer breaks down into its original material when exposed to acidic water (low pH) allowing for reuse. Strength can be increased by combining carbon nanotubes or other strengthening filler with the polymer and exposing it to high-temperature heating. The resulting polymer has properties similar to metal yet it remains lightweight. The use of this material in cars and airplanes would result in less waste and lower fuel costs.

Self-Healing Polymer

At just over room temperature, an elastic gel polymer is formed. While it is still stronger than other polymers, its elasticity is due to solvents trapped within the structure. One of the most extraordinary and surprising properties of these stretchy polymers is their ability to be self-healing. When a piece is completely severed and when held touching the two ends together, completely “self-healing” as bonds reform between the pieces reforming one solid piece almost instantly. The “self-healing” is possible due to the hydrogen-bonding interactions within the specific polymer structure.

So in the world of polymers, IBM and their esteemed associates get the blue ribbon, and as far as ribbons go, it seems green is the new blue.

Image courtesy of IBM.
Source: “Recyclable, Strong Thermosets and Organogels via Paraformaldehyde Condensation with Diamines,” by Jeannette M. García et al., Science, 2014, DOI: 10.1126/science.1251484.
Source: “IBM Research Discovers New Class of Industrial Polymers,” ibm.com, May 15, 2014.
IBM Research Discovers New Class of Industrial Polymers With Exceptional Properties,” Kurzweil Accelerating Intelligence, May 16, 2014.

EC Sets Limits on BPA in Toys

BPA in plastic toys.

The European Commission announced it is placing restrictions on the use of bisphenol A, or BPA, in toys designed for use by children under the age of 3.

The new limit — based on current levels outlined in European Standard EN 71-9:2005+A1:2007 — is “a strict limit” of a 0.1 mg/l migration limit in toys meant for children up to age 3, and for any toys designed for children to place in their mouths.

The limits are already being voluntarily used by the European toy industry. The European Commission says this has helped keep toy-based BPA exposure low when compared to exposure from contact with nonfood items such as cosmetics or dust. This is, notes the government, far lower than the exposure from BPA in the diet, based on information compiled by the European Food Safety Agency (EFSA).

Widely Used Compound

Bisphenol A — commonly referred to as BPA — is a synthetic compound with many uses, including in the production of polycarbonate plastic for electronics, automobiles, CDs and DVDs, and adult food and drink packaging. The addition of BPA to plastic makes it more flexible and shatterproof.

It is also frequently used in container linings; however, this use is under increased scrutiny. It was, for example, once used in the plastic in infant formula packaging in the United States. The plastic acted as a barrier between the formula and the metal or other materials in the container. Infant formula makers stopped using it when questions first arose about its role in fetal health. The United States Food and Drug Administration (FDA) later moved to ban the use of BPA in infant formula packaging based wholly on the fact that it is no longer used, and not because it is unsafe.

Endocrine Disruptors?

Some studies have reportedly found a link between exposure to BPA and disruption in the human hormone system. The risks these so-called endocrine disruptors pose to human health is a contentious issue among scientists, who have been embroiled in controversy and debate about BPA and other such chemicals.

Consumer and environmental groups have raised concerns about the chemical’s suitability in any food or beverage containers. Concern also has been raised about its use as a coating for cash register receipt paper. Some of these fears are irrational, some scientists have said.

Yet, in a conversation with The New York Times‘s Nicholas D. Kristof, John Peterson Myers, chief scientist at Environmental Health Sciences and a co-author of a study on BPA, said his family had stopped buying canned food and was taking other precautions to limit its BPA exposure:

We don’t microwave in plastic. [...] We don’t use pesticides in our house. I refuse receipts whenever I can. My default request at the ATM, known to my bank, is ‘no receipt.’ I never ask for a receipt from a gas station.

Voluntary End of Use

Most of the bans to date have occurred after manufacturers voluntarily stopped using the substance. This was the case in the U.S., where, although it had not been used for years in baby bottles and sippy cups, the federal government instituted a ban on its use in those items.

The European Commission summarized:

The complex health effects of BPA, including endocrine disrupting effects, are still under scientific evaluation at the EFSA and in other scientific fora. If relevant new scientific information becomes available through the ongoing scientific work, the limit that the Commission has now adopted would have to be reviewed.

Image by Dulcenombre Maria Rubia Ramirez/123RF.
Source: “EU Sets Strict Limit for Content of BPA in Toys Owing to Health Concerns of Children,” SpecialChem, June 27, 2014.
Source: “Bisphenol A (BPA) Strictly Limited in Toys,” European Commission press release, June 25, 2014.
Source: “Public Consultation on the Draft Opinion on Bisphenol A (BPA) — Exposure Assessment,” European Food Safety Authority, September 15, 2013.
Source: “Tests Find Chemical-Laden Receipts at National Retailers,” Environmental Working Group, July 27, 2010.
Source: “Debate Builds over Regulation of Bisphenol A and Other Endocrine Disruptors,” Scientific American, September 20, 2013.
Source: “How Chemicals Affect Us,” by Nicholas D. Kristof, The New York Times, May 2, 2012.

Polymer Opals: Colorful, Lasting Material

The flexible polymer opal changes color when compressed.

A new material inspired by the structure of natural gemstones has many properties its earthy counterparts do not.

Opals, which are among the most vividly colored materials in nature, obtain their colors from the reflection of light. Based on this property, the polymer opal, created by researchers from the Fraunhofer Institute for Structural Durability and System Reliability and University of Cambridge, is a flexible, colorful material that will not fade over time and that changes color when stretched.

Natural Opals

Opals form in nature when water evaporates, leaving behind tiny silica spheres. These deposits are suspended in the earth and are ordered so that the spheres diffract the visible light, which cause the beautiful, intense colors in the gems. In polymer opals, silica is replaced by nanoparticles with a rubbery outer shell.

The researchers explain:

Gemstone opals achieve their structure by the regular stacking of perfectly round glass spheres. Polymer opals also consist of ordered spheres. Using clever chemistry similar to that used in the production of latex paints, a mass of nearly identical spheres for polymer opals are synthesised with a hard central core of crosslinked polystyrene, bonded to a soft outer shell of polyethylene acrylate that has the consistency of chewing gum.

Synthetic Opals

Although synthetic opals were first made in the 1970s, they are typically brittle and, add the researchers, aren’t suited for mass market applications.

To make these new synthetic opals, the researchers expose the spheres to high temperatures, which causes them to self-assemble into a 3D crystal with structural color. Structural color refers to a color in both nature and synthetics created by diffraction. This includes peacock feathers, butterfly wings, or photonic crystals.

At these temperatures, the soft outer shells deform while the central core material becomes ordered. This regular pattern diffracts lights. In other words: the internal structure produces the color; the outer shell provides it with its elastic properties.

The precise color of the polymer opal is based on the nanoparticle size. There are small (171 nm), medium (191 nm), and large (266 nm) particles that produce blue, green, and red opals.

Changing Colors

Polymer opals can temporarily change color by deforming — that is, stretching or twisting — the material. Such deformation causes the color to change based on the space between particles changing. This change alters the wavelength at which the material reflects light. Stretching, for example, causes a green sample opal to become blue when stretched; a blue sample becomes green when compressed. These color shifts can be temporary. This property could be ideal for use in strain sensors. Such color changes should be able to show the level of stress an item attached to the material is undergoing.

Possible Applications

The colorfast nature of this material would be attractive in fabrics, as the polymer opal material could replace toxic dyes. Additionally, the color wouldn’t fade or run.

Another possible application: an alternative to holograms used in paper currency to prevent counterfeiting. The color-changing properties are difficult, but inexpensive to reproduce.

The researchers add:

A real advance is that we can make these photonic crystals by standard plastic manufacturing techniques. They are flexible, making them some of the most durable opalescent materials available, and they are suited for mass production and incorporation into consumer items.

The researchers are working to commercialize the material; however, the polymer opals are already being used in creative ways. London-based designer Rainbow Winters included fabrics based on the material at a fashion show in Paris. They also have applications in both security and sensing applications.

Among the future research they are exploring includes producing a single sheet in which there are different colors on different areas of the sheet rather than a single, uniform color.

Jeremy Baumberg, professor of nanophotonics in the University of Cambridge, department of physics, concludes:

The crucial thing is that by assembling things in the right way you get the function you want. [...]  It’s such a good example of nanotechnology — we take a transparent material, we cut it up in the right form, we stack it in the right way and we get completely new function.

Image courtesy University of Cambridge.
Video: dres2video2share, YouTube.com.
Source: “Nanosphere-Laced Polymer, Polymer Opals That Change Color Under Stress,” Plastemart.com.
Source: “Polymer Opals,” University of Cambridge, Colours.
Source: “Nanomaterials Up Close: Synthetic Opal,” by Harry Beeson, University of Cambridge, Research, June 13, 2014.
Source: “Trapping the Light Fantastic,” by Gen Kamita and Jeremy Baumberg, University of Cambridge, Research, June 16, 2014.

Polymer-Based Springs Added to Autos

Lightweight, composite car springs.

A composite spring, left, next to a conventional metal spring.

A new polymer composite suspension spring promises to bring numerous benefits to the automotive industry, benefits that drivers should ultimately be able to appreciate as well.

Audi and Sogefi, an Italian automotive parts manufacturer, collaborated on the development of a glass fiber-reinforced polymer spring, designed to replace steel springs used as part of a car’s suspension.

The spring is light green in color and reportedly is beefier than its steel counterpart. It also is slightly larger in diameter and features fewer coils than a steel spring.

The springs are made using a process patented by Sogefi in which long glass fibers are twisted together. An epoxy resin is added before additional fibers are mechanically wrapped around the twisted glass core. These other fibers are placed in such a way as to counteract possible stresses. The structure is then then cured at temperatures exceeding 100°C.

“The GFRP springs can be precisely tuned to their respective task, and the material exhibits outstanding properties,” states Audi. The material “does not corrode, even after stone chipping, and is impervious to chemicals such as wheel cleaners.”

Polymers’ Roles in Auto Industry

Polymer composite materials have been used in the automotive industry for several decades. The 1953 Chevrolet Corvette was one of the first models to feature such materials. Typically, glass fiber-reinforced polymers have been used in the industry, but other types of polymer composites, including thermoplastic composites and carbon fiber-reinforced polymer composites, are promising, according to US Department of Energy researcher Sujit Das.

Today about 245 pounds of plastics and composites are used in a typical vehicles, or about 8 percent of an automobile. This is a relatively small increase from the mid-1970s, when about 170 pounds were used per vehicle. Smaller, more fuel-efficient vehicles generally contain more plastics relative to their total weight; however, minivans contain more composite parts by weight.

The use of glass-reinforced polymers in a vehicle’s structural components could result in a 20 to 35 percent reduction in the vehicle’s weight. The use of carbon fiber-reinforced polymer materials may reduce an automobile’s weight by 40 to 65 percent. The new springs are 40 percent lighter than the steel spring it is replacing.

A steel spring for an upper mid-size car weighs about 2.7 kilograms, while the new glass fiber-reinforced polymer spring with the same properties weighs about 1.6 kilograms. The four springs on the new Audi, therefore, promise to reduce its weight by about 4.4 kilograms.

Das further observes:

Important drivers of the growth of polymer composites have been the reduced weight and parts consolidation opportunities the material offers, as well as design flexibility, corrosion resistance, material anisotropy, and mechanical properties. Although these benefits are well recognized by the industry, polymer composite use has been dampened by high material costs, slow production rates, and to a lesser extent, concerns about recyclability.

Nonstructural Elements

Composites are most often used for nonstructural elements in niche-market vehicles with annual production volumes of less than 80,000. Some parts using composites include bumper systems, instrument panels, leaf springs, drive shafts, compressed natural gas fuel tanks, intake manifolds, and wheel covers.

Dr. Ulrich Hackenberg, member of the board of management for technical development at AUDI AG, states in a release, “The GFRP springs save weight at a crucial location in the chassis system. We are therefore making driving more precise and enhancing vibrational comfort.”

Although Audi claims the springs can be used to help them tune the suspension, ultimately giving “a more precise driving experience,” Motor Trend is waiting to evaluate the claims. “It remains to be seen how the polymer springs hold up over time, but we can see how the new springs perform when they arrive on a new model later this year.

Other benefits, according to Sogefi, are reduced emissions in the manufacturing process, and when driving, as well as lower fuel consumption.

Audi plans to use the glass fiber-reinforced polymer suspension springs in an undisclosed new upper-midsized model, which some observers speculate will be the A6 or A7, to be released in Fall 2014.

Image courtesy Audi Media Services.
Source: “Sogefi, Audi Develop New Suspension Spring Technology,” reporting by Agnieszka Flak, editing by Mark Potter, Reuters.com, July 3, 2014.
Source: “Audi Polymer Suspension Springs Arrive on Unnamed Model This Fall,” by Jason Udy, wotmotortrend.com, June 30, 2014.
Source: “Audi Set to Cut Vehicle Weight with Introduction of Fiberglass Springs,” by Scott Collie, Gizmag.com, July 2, 2014.
Source: “New Patented Lightweight Springs to Be Introduced by Audi by Year End,”sogefigroup.com, July 3, 2014.
Source: “Audi Bringing New Lightweight Springs to Production Models,” Audi.com, June 30, 2014.

Technique Grows Metal-Organic Membranes Inside Fibers

Growing metal-organic framework membranes inside hollow polymer fibers.

Georgia Tech researcher Andrew Brown places a finished hollow fiber metal-organic framework (MOF) membrane module into a testing apparatus to measure its gas separation properties.

A new fabrication method for growing metal-organic framework membranes inside hollow polymer fibers has been developed by Georgia Institute of Technology researchers, who say it promises to change large-scale, energy-intensive chemical separation processes.

This is thought to be the first method for growing metal-organic framework membranes in hollow fibers.

Molecular sieving membranes use semipermeable materials to separate molecules from mixtures made via chemical reactions, or from raw material feedstocks. The membranes pass only certain molecules through their pores. To date, other researchers have developed membranes using crystalline materials known as zeolites, but these are costly and not widely available, which has hampered their wider use.

Affordable Technology

Researchers thought metal-organic framework membranes had the potential to replace other energy-intensive industrial separation processes, but first, they had to find a method for making them affordably and in large volumes.

They used hollow fibers spun from inexpensive polymers to create the new membranes. Each fiber is a few hundred microns in diameter. A microfluidic technique brings together reactants needed to form the membranes inside the fibers. Since the inner diameter of the fibers may be 100 microns or less, the amount of reactant that can be used to fabricate the membrane is limited; the size also affects the physical and chemical forces responsible for membrane formation.

To control the location of the membrane films, researchers had to change the flow and the position of both the reactants and solvents used in the process, using, for example, two different solvents flowing in opposite directions to deposit the material selectively within the hollow fibers. In some cases, the films were formed outside or within the fiber structures. This allowed the process to be scaled up, thereby lowering the cost.

Scaling up Production

Fabricating hollow-fiber metal-organic framework (MOF) membranes.

This close-up photograph shows the prototype reactor module used to fabricate hollow-fiber metal-organic framework (MOF) membranes at Georgia Tech using the interfacial microfluidic technique.

After they were able to make a membrane with a single hollow fiber, the team sought to make membranes in parallel using multiple hollow fibers preassembled into a module. Specifically, they used a compound known as ZIF-8 — zeolitic imidazolate frameworks, a metal organic framework with properties like zeolites, including porosity — to make the metal-organic framework inside three fibers at the same time.

Based on their findings, the researchers say they may be able to preassemble large bundles of the polymer fibers, then coat these at the same time with some sort of metal-organic framework to make larger metal-organic framework membranes with a greater surface area. A 1-cubic-meter hollow-fiber membrane module could contain 10,000 square meters of membrane area.

Gas and Liquid Separation

The use of such metal-organic framework membranes may eventually be able to reduce the costs of other more energy-intensive processes for gas and liquid separation, such as distillation. It could also decrease the amount of carbon dioxide generated in the process.

Demonstrations of these novel membranes have been limited to separating hydrocarbon gas mixtures — hydrogen from hydrocarbon mixtures and propylene from propane — that might be used by the petrochemical industry; however, this membrane processing technique could have broader applications, according to Christopher Jones, a Georgia Institute of Technology professor of chemical and biomolecular engineering who worked on the project:

The approach we have developed could open the door to a whole new class of molecular sieving, polycrystalline film membranes. [...]  Such membranes could revolutionize how oil and chemical companies carry out gas and liquid separations, for example, by replacing energy-intensive and expensive cryogenic distillation processes with more energy-friendly membrane separations.

It could be used for other industrial processes, including the production of bio-based fuels and chemicals.

Next, the researchers want to better understand the microscopic level conditions in the process. Understanding the chemical reactions and molecular-level transport processes that occur as the membrane is formed may help them optimize and scale their technique.

Additional collaborators included scientists formerly with Georgia Institute of Technology, now affiliated with The Ohio State University and SABIC.

The research was supported by Phillips 66 Company.

Images by Rob Felt, courtesy of the Georgia Institute of Technology by Rob Felt.
Source: “Interfacial Microfluidic Processing of Metal-Organic Framework Hollow Fiber Membranes,” by A.J. Brown, N.A. Brunelli, K. Eum, F. Rashidi, J.R. Johnson, W.J. Koros, C.W. Jones, and S. Nair,Science,Vol. 345 No. 6192 pp. 72-75, July 4, 2014; DOI: 10.1126/science.1251181.
Source: “Hollow-Fiber Membranes Could Cut Separation Costs, Energy Use,” PhysOrg, July 3, 2014.
Source: “Exceptional Chemical and Thermal Stability of Zeolitic Imidazolate Frameworks,” by K.S. Park, Z. Ni, A.P. Cote, J.Y. Choi, R. Huang, F.J. Uribe-Romo, H.K. Chae, M. O’Keeffe, and O.M. Yaghi, Proceedings of the National Academy of Sciences of the U.S.A., doi: 10.1073/pnas.0602439103, May 22, 2006.

John Recalls Pirates in the Lab …

Let us introduce you to …

John Winebarger

ACS Laboratory Technician and Quality Specialist

John Winebarger

John Winebarger, ACS laboratory technician and quality specialist

How long have you worked at PSI and what did you do before?

I’ve been at PSI for two years. Prior to that, I was in school at Virginia Tech getting a double degree in Biochemistry and Chemistry. I worked at the Fralin Life Science Institute at Virginia Tech in their biotechnology outreach program, which loaned out all-inclusive science kits to Virginia high schools. They included gel electrophoresis, column chromatography, and immunology.

Do you think anything you do during a typical day would surprise people?

Usually after arriving I’ll head up to the front kitchen and brew a cup of Yorkshire tea and chat with the other caffeine addicts for a few minutes. Then I’ll touch base with my lab manager Alan and plan out my day based on the work he assigned me. Then I get to work. I have a few other random responsibilities as well, such as overseeing the glassware stream for the company, ensuring that all the labs have adequate glassware for their needs and ensuring that dirty stuff is addressed promptly by our general technicians. I’m also loosely affiliated with the Quality Department, evaluating our vendors and maintaining their documentation in our quality system.

What’s a common misconception about the work you do, and why do you think that is?

Probably the biggest misconception is that the work we do always gives us concrete results, unwaveringly, and quickly, much like how you see it happen on television. In reality, the results aren’t always so absolute, and they’re almost never quick and convenient. A lot of the science we do requires a skilled pair of eyes to look through the data and make a proper interpretation, or sometimes, no interpretation if the experiment simply didn’t work.

Behind the scenes, for the more complicated projects with larger scope, there sometimes has to be some trial and error before you find the best way to tackle the questions the client wants answered. Often this is hashed out in advance by our experts, but sometimes you don’t find out what will work until you’re actually in the lab trying it. Sometimes this can mean treading new ground internally for our clients and expanding our scope of expertise.

What’s been your favorite project at PSI so far, and why?

It’s hard to pick any one project, but it’s always the most fun to test the more random things we receive. You never know what new, challenging, and interesting surprise is walking in with the mail any particular day. For example, one week we might test tear gas, and the next, analyze seal blubber.

For the record, the smell of rancid seal blubber is not pleasant.

Another one that comes to mind isn’t really appropriate to talk about, but I’ll say we analyzed manufacturing problems in an adult product and leave it at that. Those kinds of projects are where a lot of the adventure of this job comes in.

What’s the weirdest thing you’ve ever done at PSI?

I’d have to say doing lab work dressed as a pirate is up there. Our annual Talk Like a Pirate Day celebration creates an odd day at a testing lab, with people alternating between lab work, sword fights in the parking lot, and 17th century pirate murder mysteries in the conference room. Just remember that an eyepatch isn’t appropriate lab PPE.

PSI is a unique place, no doubt about that.

PSI prides itself of accepting new challenges. What project(s) have challenged you and given you satisfaction upon completion?

I can’t get into specifics of course, due to client confidentiality, but I did a lot of work for a particular patent litigation case where we analyzed a set of knock-off medical devices manufactured in China and compared them to the patented domestic product. That case stands out because I remember getting to follow it until its resolution in the courts, which was particularly satisfying.

If someone made a TV show or film about PSI, who would you want to play you, and why?

Chris Hemsworth, so one day I can sit down with my kids and watch it and say, “Look how handsome your dad was when he was young! And also he was a superhero for a while, no big deal.”

Thinking back on great scientists in history … who is your favorite and why?

There are too many instrumental figures in the past to just choose one, so I’m going to aim for the present instead. I think Neil DeGrasse Tyson is one of the most important scientists of the day. Not for his discoveries or research, but for his ability to convey science to the non-scientific masses. There’s a troubling anti-science sentiment that exists in some circles in the country these days, so it’s hard to overestimate the importance of a scientist who can connect with the average American so well, and turn science into something more than an annoying class from high school. Without scientists like him, the value of science – not to mention the understanding of its basic tenets — would be lost on so many people.

What do you do for fun outside of work? Does it relate to what you do during the week?

At the moment, my interests include traveling internationally whenever possible, taking good care of my dog, running, and exploring/camping in the great outdoors. So it really has nothing to do with my job, except that I get to thank PSI for cultivating my interest in running. In the past year, a good group of us have started training for 5Ks (and eventually 10Ks). I guess that rubbed off from the Rancourts, a family full of runners.

3D Printing Creates Artificial Blood Vessels

Scientist have developed a promising technique for the vascularization of 3D-printed organs.

Blood vessels form an intricate network, transporting nutrients and oxygen throughout the body and disposing of waste, keeping organs working properly.



Using 3D printing, medical researchers have been able to create artificial blood vessels based on the human circulatory system.

According to the international team of researchers from the University of Sydney, Harvard and Stanford universities, and the Massachusetts Institute of Technology, the technique is fundamental for growing large, complex tissues, and is a step toward printing transplantable tissues and organs.

Intricate Network

Blood vessels form an intricate network, transporting nutrients and oxygen throughout the body and disposing of waste, keeping organs working properly. Cells die without an adequate supply of oxygenated blood. The intricacy involved in growing blood vessels and capillaries has typically posed a challenge for medical researchers trying to move toward the engineering of large tissues and organs.

Ali Khademhosseini, a biomedical engineer and director of the Brigham and Women’s Hospital Biomaterials Innovation Research Center, explains:

Engineers have made incredible strides in making complex artificial tissues such as those of the heart, liver and lungs. [...] However, creating artificial blood vessels remains a critical challenge in tissue engineering. We’ve attempted to address this challenge by offering a unique strategy for vascularization of hydrogel constructs that combine advances in 3-D bioprinting technology and biomaterials.

Template for Vessels

Their technique for constructing the network of blood vessels is based on 3D printing, which enabled them to make a template of numerous interconnected fibers. This fiber structure was used as a mold for the artificial blood vessels. The mold was created using agarose, a sugar-based molecule fiber and natural hydrogel-producing polymer.

The mold was covered with a protein-based material known as a hydrogel and reinforced with photocrosslinks, a means of forming bonds between molecules. Several common hydrogels were tested by the researchers, including methacrylated gelatin, a material often used in tissue engineering, and poly(ethylene glycol)-based hydrogels.

Tiny Channels

The agarose templates, when physically removed from the structure, leave a network of tiny channels. This material does not have to be dissolved, which has the potential to affect any cells encased in the gel. These channels are coated with human endothelial cells — the same cells that line human blood vessels — that have a range of functions, including creating new blood vessels.

These new bioprinted vascular networks, say the researchers, “promoted significantly better [endothelial] cell survival, differentiation and proliferation compared to cells that received no nutrient supply.” In other words, they work.

University of Sydney researcher Dr. Luiz Bertassoni explained the need this technology fills:

Thousands of people die each year due to a lack of organs for transplantation. [...] Many more are subjected to the surgical removal of tissues and organs due to cancer, or they’re involved in accidents with large fractures and injuries. While recreating little parts of tissues in the lab is something that we have already been able to do, the possibility of printing three-dimensional tissues with functional blood capillaries in the blink of an eye is a game changer.

Although tissues can be replicated in the lab now, what these researchers are ultimately striving to do is regenerate complex, functional organs through a marriage of engineering and medicine. Perhaps one day, they theorize, a patient would be able to walk into a hospital and have an organ printed according to their specific needs. This bioprinting technique could be used to properly print all the cells, proteins, and blood vessels needed from a prompt on a computer screen.

They consider the printed structures they are now making to be prototypes that will evolve as the technique is improved and refined.

Khademhosseini added:

In the future, 3D printing technology may be used to develop transplantable tissues customized to each patient’s needs or be used outside the body to develop drugs that are safe and effective.

The researchers published their work — “Hydrogel Bioprinted Microchannel Networks for Vascularization of Tissue Engineering Constructs” — in the online journal Lab on a Chip.

Image by blueringmedia/123RF.
Source: “Hydrogel Bioprinted Microchannel Networks for Vascularization of Tissue Engineering Constructs,” by L.E. Bertassoni, A. Khademhosseini, et al., Lab on a Chip, Issue 13, 2014, DOI: 10.1039/C4LC00030G.
Source: “3-D Printing Breakthrough: Researcher Calls Ability to Bioprint Blood Vessels a ‘Game Changer,’ ” by Punditty, AllVoices, July 1, 2014.
Source: Brigham and Women’s Hospital.
Source: “A Step Closer to Bio-Printing Transplantable Tissues and Organs,” University of Sydney, July 2, 2014.
Video: “3D Printing at BWH,” by BWH Public Affairs.