28 June 2019 Bulletin

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Simazine is an herbicide of the triazine class, with the molecular formula C7H12ClN. [1] Under normal conditions, Simazine is a white crystalline powder. When mixed with air, its dusts can be explosive. When heated, Simazine breaks down to give toxic fumes. It melts at 225 degrees Celsius. Simazine is not very soluble in water, but dissolves well in organic (carbon-containing) solvents. [2] Like atrazine, a related triazine herbicide, it acts by inhibiting photosynthesis. It remains active in the soil for 2-7 months after application. [1]

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Ahead of most other countries, Colombia bans asbestos

It took Colombia’s congress 12 years, but the production, sale and use of asbestos was banned recently because of its health hazards. The ban will take effect in 2021 and allows local companies that use the mineral in its products a five-year transition period phase out the use of the mineral that is well known for causing, among other things, lung cancer. Ahead of the vote, the lawmakers heard citizens who had fallen ill to a variety of diseases believed to have been caused by asbestos. Other witnesses to the debate brought images of loved ones who died because of their exposition to the cancerous mineral that has long been used in construction. The House of Representatives, which had the final vote on the issue, unanimously agreed to the ban, much to the joy of the invited victims. The mining and export of the controversial mineral was also banned. According to the World Health Organization, more than 100,000 people die annually as a result of their exposure to asbestos fibres. According to website Pulzo, the debate to ban asbestos gained support after journalist Ana Cecilia Niño found she got cancer as a consequence of living next to a factory using the mineral and spent her dying days campaigning to make Colombia asbestos-free. The journalist died in 2012. Despite decades of civil lawsuits, industry lobbyists have so far been able to maintain asbestos legal in the United States. Also, in the European Union, legislation to ban or limit the use of the controversial mineral has been difficult to implement. Colombia is the seventh country in the world to fully ban asbestos.


Research team develops bioinks to print therapeutics in 3-D

3-D bioprinting is emerging as a promising method for rapidly fabricating cell-containing constructs for designing new, healthy, functional tissues. However, one of the major challenges in 3-D bioprinting is lack of control over cellular functions. Growth factors, which are a special class of proteins, can direct cellular fate and functions. However, these growth factors cannot be easily incorporated within a 3-D-printed structure for a prolonged duration. In a recent study conducted at Texas A&M, researchers in Dr. Akhilesh K Gaharwar’s lab in the Department of Biomedical Engineering formulated a bioink consisting of 2-D mineral nanoparticles to sequester and 3-D print therapeutics at precise locations. Their findings were published in Advanced Healthcare Materials. The team has designed a new class of hydrogel bioinks—3-D structures that can absorb and retain considerable amounts of water—loaded with therapeutic proteins. This bioink is made from an inert polymer, polyethylene glycol (PEG), and is advantageous for tissue engineering because it does not provoke the immune system. However, due to low viscosity of the PEG polymer solution, it is difficult to 3-D print this type of polymer. To overcome this limitation, the team has found that combining PEG polymers with nanoparticles leads to an interesting class of bioink hydrogels that can support cell growth and may have enhanced printability compared to polymer hydrogels by themselves. This new technology, based on a nanoclay platform developed by Gaharwar, assistant professor, can be used for precise deposition of protein therapeutics. This bioink formulation has unique shear-thinning properties that allow the material to be injected, quickly stop flowing and then cure to stay in place, which is highly desirable for 3-D bioprinting applications. “This formulation using nanoclay sequesters the therapeutic of interest for increased cell activity and proliferation,” said Dr. Charles W. Peak, senior author on the study. “In addition, the prolonged delivery of the bioactive therapeutic could improve cell migration within 3-D printed scaffolds and can help in rapid vascularisation of scaffolds.” Gaharwar said the prolonged delivery of the therapeutic could also reduce overall costs by decreasing the therapeutic concentration as well as minimising the negative side effects associated with supraphysiological doses. “Overall, this study provides proof of principle to print protein therapeutics in 3-D that can be used to control and direct cell functions,” he said.


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