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Flowers usually open to the sun, but scientists at the University of North Carolina at Chapel Hill have engineered a polymer bloom that unfurls over the course of two hours, due to the location, strength and number of its molecular bonds. This feat of hydrogel horticulture isn’t just aesthetically pleasing, it also demonstrates how a material can be programmed to change shape over hours and minutes, without an external trigger.

Covalent vs. Physical Crosslinks

The UNC team based their smart material on a soft polymer with the texture of human cartilage. The majority of bonds are reversible physical crosslinks which are easily broken and give the polymer its flexibility. A small portion of the polymer’s molecular bonds are covalent crosslinks, which enable the material to return to its original shape after being stretched, like a rubber band. The UNC team adjusted the molecular structure of their polymer so the physical crosslinks would act as a brake against shape recovery by the covalent crosslinks, allowing control of the rate of shape change.

Biomedical Applications of Shape-Changing Polymers

The ability of smart materials to change shape and function without an outside trigger has many potential biomedical applications, including slow-release drug delivery and minimally invasive surgical procedures.

CPG works with shape-memory materials as well, incorporating them into medical devices to produce environmentally-responsive devices. Our devices respond to temperature, fluid environment, salinity and pH as appropriate.

Journal reference: Nature Communications, 10.1038/ncomms12919

The New England office of Cambridge Polymer Group is fortunate to see the brilliant color display every fall as the foliage undergoes its autumnal transformation. Our work in polymer chemistry naturally starts us down the path of wondering what is happening to the leaves to cause this color change. 

The colors in leaves come from three principle sources:

Chlorophyll

Chlorophyll is responsible for photosynthesis in leaves, and provides them with their green color.

Anthocyanins

Anthocyanins provide the reddish colors found in fruits such as cherries, strawberries, and cranberries.

Carotenoids

Carotenoids provide the orange, brown, and yellow colors in fruits and vegetables like bananas and corn, as well as egg yolks and flowers.

Chemical composition of leaf color

Chlorophyll is produced during the growth of plants, typically in the spring and summer when there is more daylight, resulting in the lush green appearance we associate with those seasons. When the days start to grow shorter resulting in less light, chlorophyll production slows and eventually stops. The chlorophyll eventually degrades and disappears, along with its green color. The remaining pigment types, anthocyanins and carotenoids, which were there all along but dominated by the green chlorophyll, now emerge.

Species vs. Weather

The amount and type of color will depend on the species of tree or bush, but also depend on the weather leading up the fall. Warm days and cool nights will result in the production of sugars in the leaves during the day, with the cool nights keeping the sugars in place by closing off the veins in the leaves. The sugars aid in production of anthocyanin, or the red colors we clamor to see in late September in the New England area.

Use of power morcellators to perform hysterectomies declined after an April 2014 FDA warning, according to a study published in JAMA.

Columbia University researchers examined hysterectomy trends before and after the 2014 warning that morcellation may cause the spread of cancer in patients with undetected sarcoma. Among women who underwent minimally invasive hysterectomy, power morcellation was used in 13.5 percent in Q1 2013, peaked at 13.7 percent by Q4 2013, and declined to 2.8 percent by Q1 2015.

An electric power morecellator is used during hysterectomy or fibroid removal, if the tissue is too large to extract through laparoscopic incisions. The morcellator pincers grip the tissue and then pull back into the shaft, where the tissue is minced by a rotating blade. If an undetected sarcoma gets cut by a morcellator, the cancer may spread throughout the abdomen and pelvis.

CPG has worked with companies in the woman’s health arena to develop training tools for fibroid removal including tissue and organ models  that replicate the cutting behavior of native tissue. We also provide services in analyzing the cleanliness of biomedical devices, including reprocessing re-usable medical devices such as morcellators. 

Patients who have undergone a heart attack often have thinned-out or otherwise weakened heart walls, which can result in inefficient blood circulation and/or regurgitation, leaving the patient weakened and out of breath. Researchers at the University of Pennsylvania have developed a biodegradable hydrogel based on hyaluronic acid that can be injected into the walls of the heart in a patient who has undergone a heart attack. The liquid gels in the damaged walls of the heart through the addition of thiol and methacrylate groups, which crosslink the hyaluronic acid. The UPenn team hopes that the approach will result in a stiffened, and therefore more reliable, heart wall.

Injectable hydrogels have been used to improve heart function for several years, including work done at Cambridge Polymer Group. Since 2006, CPG has collaborated with cardiovascular researchers at the Massachusetts General Hospital. In several studies, this collaboration has demonstrated that a novel injectable hydrogel developed at CPG can be injected into the hearts of sheep with induced ischemic mitral regurgitation, and the hydrogel-strengthened heart walls can reverse the effects of the mitral regurgitation. 

The hydrogel is based on polyvinyl alcohol, and undergoes no chemical reaction to form the gel, which helps in its safety profile. This approach is minimally invasive, and provides a potential long-term solution to hearts damaged from cardiac events. Read more about the publications by CPG and MGH on this subject here.

On Friday, September 2^nd 2016, the FDA issued a final rule banning the use of 19 different chemicals in antibacterial soaps. The final rule applies to consumer wash products containing one or more of the 19 banned chemicals including the most commonly used ingredients in liquid and bar soaps, triclosan and triclocarban.

According to the U.S. Food and Drug Administration (FDA), there is lack of scientific evidence to support the claim that antibacterial soaps are more effective than plain soap and water. In addition, there is some data suggesting long-term exposure to certain antibacterial chemicals can pose health risks such as bacterial resistance, muscle weakness, and hormone cycle disruption.

In December of 2013, due to consumers’ extensive exposure to the chemicals, the FDA issued a proposed rule requiring manufacturers to provide safety and efficacy data on their products. Several companies began phasing out these chemicals; however, those still utilizing them were required to prove the long-term safety for daily use as well as greater effectiveness in comparison to plain soap and water.

Upon finalization of the rule on September 2^nd, 2016 no manufacturers had provided the minimum data necessary to prove the safety and efficacy of any of the 19 banned chemicals. Therefore, the FDA lacked evidence to find the chemicals Generally Recognized as Safe and Effective (GRAS/GRAE). Companies currently using the banned ingredients will have one year to eliminate them or remove their products from the market altogether. The rule does not apply to hand sanitizers or antibacterial agents used in healthcare settings.

If you are seeking to identify triclosan or other antibacterial agents, GC-MS can be used to detect trace levels of antibacterial chemicals in municipal water, soils, and consumer products. CPG performs routine and custom GC-MS, and can assist in determining quantitative levels of antibacterial agents in materials. 

CPG President Stephen Spiegelberg will be chairing the ASTM workshop "Reprocessing of Re-Usable Medical Devices" on November 15, 2016 in Orlando, Florida.

A recent article in Medical Processing Outsourcing (June 2, 2015) estimates that reprocessed medical devices will grow by 19% annually to reach $2.58 billion in 2020. A key element of this successful growth is assurances of cleanliness and safety standards.

Recently, the FDA released a guidance document on reprocessing of reusable devices (March 12, 2015) and held a public meeting on May 14-15, 2015 to discuss infections associated with the use of duodenscopes. 

Workshop registration ends November 9, 2016.