Monday, July 19, 2010

Artificial Cells Communicate and Cooperate Like Biological Cells, Ants

Recently reported in the Proceedings of the National Academy of Sciences (PNAS), the research is a significant step toward producing synthetic cells that behave like natural organisms and could perform important, microscale functions in fields ranging from the chemical industry to medicine.


The team presents in the PNAS paper computational models that provide a blueprint for developing artificial cells -- or microcapsules -- that can communicate, move independently, and transport "cargo" such as chemicals needed for reactions. Most importantly, the "biologically inspired" devices function entirely through simple physical and chemical processes, behaving like complex natural organisms but without the complicated internal biochemistry, said corresponding author Anna Balazs, Distinguished Professor of Chemical Engineering in Pitt's Swanson School of Engineering.









In one video of the interaction, as the signaling cell emits the agonist nanoparticles, the target cell responds with antagonists that stop the first cell from secreting. Once the signaling cell goes dormant, the target cell likewise stops releasing antagonists -- which makes the signaling cell start up again. The microcapsules get locked into a cycle that equates to an intercellular conversation, a dialogue humans could control by adjusting the capsules' permeability and the quantity of nanoparticles they contain.

Monday, July 5, 2010

Oil Spills Raise Arsenic Levels in the Ocean,says Research

Arsenic is a poisonous chemical element found in minerals and it is present in oil. High levels of arsenic in seawater can enable the toxin to enter the food chain. It can disrupt the photosynthesis process in marine plants and increase the chances of genetic alterations that can cause birth defects and behavioural changes in aquatic life. It can also kill animals such as birds that feed on sea creatures affected by arsenic.



                                 In the study, a team from Imperial College London has discovered that oil spills can partially block the ocean's natural filtration system and prevent this from cleaning arsenic out of the seawater. The researchers say their study sheds light on a new toxic threat from the Gulf of Mexico oil leak.








Arsenic occurs naturally in the ocean, but sediments on the sea floor filter it out of seawater, which keeps the levels of naturally occurring arsenic low. However, arsenic is also flushed into the ocean in wastewater from oil rigs and from accidental oil spills and leakages from underground oil reservoirs.



            In the study, the researchers discovered that oil spills and leakages clog up sediments on the ocean floor with oil, which prevents the sediments from bonding with arsenic and burying it safely underground with subsequent layers of sediment. The scientists say this shutdown of the natural filtration system causes arsenic levels in seawater to rise, which means that it can enter the marine ecosystem, where it becomes more concentrated and poisonous the further it moves up the food chain.


                                                                                                                      
The team carried out experiments in the laboratory that mimicked conditions in the ocean, to see how the goethite binds to arsenic under natural conditions. They discovered that seawater alters the chemistry of goethite, where low pH levels in the water create a positive change on the surface of goethite sediments, making them attractive to the negatively charged arsenic.