Wednesday, April 20, 2011

Lab on chip technics--- Metal nanoparticles and mini systems

Lab on chip is now. Chip as you know is really small so the agents for detection or reaction should be small too. So lots kinds of nanoparticles are widely used in those minisystems for disease diagnose, pathogen detection and microbiology purification.

First the name of Nano is formally use as prefix to indicate unit multiplication by 10-9. And nanoparticles are size between 1 to 100 nm. Because of their sizes, they have many unique size-depended properties like large surface area and unexpected optical properties as they are small enough to confine their electrons and produce quantum effects. For example gold nanoparticles appear deep red to black in solution which is usually yellow in bulk. And metal nanoparticles which with high surface area, high mechanical strength but ultra- weight, rich electronic properties and excellent chemical, thermal stability and high sensitivity are common used for detection assays. AuNPs (gold nanoparticles) due to those properties like it can be synthesized in a various forms and sizes using different chemical methods which can be attached to many traditional biological probes such as antibodies, ion, DNA and receptors. Here are some examples of how attached nanoparticle works in different detection assays. As what I worte gold nanoparticle has property of scatting and absorbing light. Many cancer cells have unique receptors called EGFR over the cells’ surface and the receptors can be used as the target for the cancers. When the nanoparticle is attached the antibody of EGFR called anti-EGFR the nanoparticle can attach to the surface of the cancer cell. Once it attached, the gold nanoparticle can flashed and make the cancer cell distinguished from the healthy cell. Like the last picture. Here is another example of how gold nanoparticle works to detect DNA. The DNA detection is utilized in a chip-based system based on a sandwich assay. This assay consists of an oligonucleotide-modified glass slide, a NP probe and target DNA. The immobilized DNA strand recognizes the DNA of interest and changes the melting profiles of the targets from an array substrate. This change gave the differentiation of an oligonucleotide sequence from targets with single nucleotide mismatches with a high selectivity.

Those nanoparticles are just like researchers in lab and now I will talk a little about the minibiosensor system like microfluidic chips which is like lab rooms. Recently, miniaturized systems and analyses have become powerful tools in chemical and biological systems due to their high performance, design flexibility, reagent and sample economy, high throughput, miniaturization and automation. Thus, microfluidic devices can dramatically alter the speed and scale of analyses. In biosensing systems in particular, the use of microfluidic chip-based sensors has outstanding advantages, small volumes (nl, pl, fl), small size, low energy consumption, cheap and disposable , high selectivity and sensitivity. There is widely known commercial which tell people a microfluidic device to detect STDs on cellphone kit with is based on this principle.

The integration of metal-NP-based electrochemical detection with microfluidic chips offers a significant advantage because it combines sensitive electrochemical detection with a compact microfluidic platform, thus using the benefits of both technologies. Those two tiny things get together which both have high sensitivity and quick and accurate properties. Therefore, the fabrication of a new platform of miniaturized devices for bioanalysis is a great challenge that will likely be applied in diverse fields, including clinical diagnosis, food analysis, process control and environmental monitoring, in the near future.

Posted by Minhui Dai

Wednesday, April 6, 2011

Quackery by any other name: Intelligent Design and the future of American antievolutionism.

--This textbook contains material on evolution. Evolution is a theory, not a fact, regarding the origin of living things. This material should be approached with an open mind, studied carefully, and critically considered
--Cobb County Board of Education; March 28, 2002

Antievolutionists are an interesting group of people—as are Scientologists, mind-readers and the ever-so forward-looking people of the Flat Earth Society. The aforementioned groups are all easily dismissed as ignorant people with their heads in the collective sand, though there is a very real problem: they all vote. Anti-evolutionists; however, pose the greatest threat to American science education, and that's after the budget slashing and over-regulation and bad turnover and a whole host of other problems public education already faces.

This is the point where blood begins to boil; however, like all seemingly unending issues, this one, too, must be put in a historic context:

John T. Scopes, a teacher from Tennessee, was arrested and prosecuted in 1925 for teaching evolution in public school, setting in motion what would become a nearly 200 year legal war in the American public school system. Now, if you thought Scopes was done and over with in 1925, think again. The Butler act—the law that Scopes was arrested under in 1925—remained on the books until 1960. Shortly thereafter, Creationism was repackaged as Intelligent Design and was again taught in some public schools until the 2005 Dover Trial, which exposed ID as a tool for injecting religion into public schools. With no scientific backing, its proponents—mostly lawyers and a handful of failed academics—resorted to subtle subterfuge and flat-out falsehoods. The problem, at its core, is religious fundamentalism.

According to literal interpretations of the bible, it is impossible to accept evolution because it goes directly against Genesis and “original sin,” as clearly indicated by other organisms preceding humans. Thus, fundamentalists claim that acceptance of evolution must lead to the disbelief god, which further leads to materialism, communism, Nazism, etc. For those who think I'm extrapolating, the “recommended literature” section of the Discovery Institute boasts the titles “From Darwin to Hitler” and “Darwin's God: Evolution and The Problem of Evil” in the very first column. Science aside, their arguments often fall into the well known literary, logical fallacy of Pandora's Box—a sign of pure philosophic ignorance compounded with a pre-existing scientific one.

As absurd and unfounded their arguments are, the creationists never cease to amuse. Between the Creation Museum (which depicts humans riding dinosaurs,) statements that the world is 6000 years old or that fossils were “placed by god to test our faith,” the straight-faced delivery of these arguments is enough to cause a scientist to re-calibrate their lack of faith in humanity, or stay well humored, depending on your point of view. Either way, we are left with a simple question: with all of the creationist arguments seemingly thrown out the window, how are these people still able to wield any influence in public education?

Enter Michael Behe, an x-cell biologist who published the only paper in Nature making an argument for Irreducibility Complex. This was at the hight of the evolution debate in 2004 and, given the style of Nature, an article evaluating Behe's article was simultaneously published. It turns out that Behe's work was wholly unfounded and did not take into account any recent literature, once again proving the illegitimacy of creationism.

Despite global condemnation from scientists during the peer-review process, Behe's article was—and is—heralded as a legitimate biochemical argument against evolution by creationists and some politicians. While the jury is thankfully settled on keeping creation and other forms of pseudoscience out of the classroom, this 2004 article seems to be the last false-argument the creationists intend to pedal in the years to come. In the world of science, Behe's argument was immediately rendered to be incorrect, though in the world of politics, it might just be a while before we actually see the end of it.

Posted by Alexander Simolaris

Effects of Banding on Penguins

The health of the Earth has been a pressing concern for environmental scientists since the global temperatures have been increasing. One of the most impacting is the events in North and South Poles, where ice caps and glaciers are melting rapidly. The melting caps cause serious problems in the ecosystems and across the world.

To track some of the changes in the marine ecosystems, scientists tag penguins to monitor their habits. In this particular article, the evaluation was done on king penguins (Aptenodytes patagonicus). It is suggested that the interpreted data based on the effects of climate change is not accurate because of the tagging. The results of the ten year study show that banding can impair reproduction because 39% of banded penguins produce fewer chicks and have a lower overall survival rate by 16%.

It is believed that penguins will not be able to adapt to banding and this method of collecting data should be stopped. The reliability of the data collected for the climate change evaluation is not high enough to support any actual effects on the ecosystems.

Posted by Liz Stangle (3)

New Genes adding to the development of Alzheimer's Disease

A largest study was done in identifying four new genes that are linked to Alzheimer’s disease. Researchers from a consortium of 44 universities and research institutions in the United States, including Rush University Medical Center worked together in findings of new genes involved in developing risk for Alzheimer’s disease in which each gene is linked to the formation of dementia later in life.
In the study, the Alzheimer’s Disease Genetics Consortium contributed in analyzing more than 11,000 people with Alzheimer’s disease and also about same number of elderly people who have no symptoms of dementia. The Rush Alzheimer’s Disease Center contributed clinical and genomic data from more than 1,500 participants in the Rush Orders Study and the Rush Memory and Aging Project. Three other consortia conducted data from additional people. Over 54,000 of people were analyzed in this study. The four genes are confirmed that are involved with Alzheimer’s disease. These genes include MS4A, CD2AP, CD33 and EPHA1, which contribute to identifying and confirming other two genes, BIN1 and ABCA7. The gene for apolipoprotein E-e4, APOE0e4 has been identified over 15 years ago and is known to have largest effect on risk. Also, other genes including CR1, CLU, and BIN1 were found over past two years.
Identifying new genes has led to believe that it provides major clues about the causes of the disease, which is very critical information to the drug discovery. In addition, this study can help researchers find and understand the pathogenic mechanisms that are involved in the developing this disease, which takes place in the brain by destroying larger parts of the brain and causing complete loss of cognitive abilities before any symptoms appear.

Posted by Arpita Patel