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Quantum dots to amplify vision

The number of people with damaged vision is getting bigger every day. That can be due to various reasons — looking at computer/TV displays, diabetes, and many more. That’s why technology is obliged to find a solution that will be able to repair vision and “renew” people’s eyes.

One of the most popular solutions so far were bionic eyes. A silicon chip gets implanted into the eye to electrically stimulate the retina’s nerves in response to light. Their main flaw of these devices is their size — because of it they block light that would have fallen on healthy parts of the retina and they can also cause tissue damage, such as tearing.

Jeffrey Olsen, a doctor from University of Colorado Hospital, has invented a brand new technique — amplifying the light that reaches the retina using the eye’s still functioning light-sensitive cells.

That’s where quantum dots step in. “Light amplification could be achieved by implanting quantum dots – nanoscale specks of semiconductor – into the retina,” he says. These fluoresce when hit by photons and would have the effect of making any received retinal image brighter.
Quantum dots have some very important characteristics — they require no external power source, their are relatively small in size, and can be coated with a bioactive material that causes them to become lodged in only specific tissues in the retina.

Tests were done on rats and they have been successful. Rats that had quantum dots injected into their retinas afterwards had more electrical activity in their retinas than those that received control injections of saline, or no treatment at all.

eye-quantum-dots

Patent: wipo.int/pctdb/en/wo.jsp?WO=2008106605 ; Photo: WIPO

How asbestos causes the deadly mesothelioma cancer

Asbestos is a silicate mineral with long and thin crystals and it’s best known for it’s toxicity. If the toxic asbestos fibers get inhaled, it can lead to various heavy illnesses, such as mesothelioma, lung cancer or asbestosis. It’s main characteristics are heat resistance and high durability, and because of that it was used in the past a lot. When it got clear that it’s very toxic, it’s use was regulated and brought to a minimum.

Researchers at the Ohio State University have launched a research project which aims to monitor the bonding between the asbestos fibers and human cells. Although they are aware that clinical trials could be years away, they hope that the data gathered from this research could help in drug development for treating deadly diseases asbestos fibers cause, such as mesothelioma.

They method they’re using in this research is called atomic force microscopy. What they’re actually doing here is observe how asbestos fibers bind with specific receptors on the cell surface. They suspect that asbestos fibers cause a chain of events inside human cells, and that makes them ill. Eventually, the die. “We can feel and observe what’s happening on molecular surfaces,” said Eric Taylor, a coauthor of the study. “We’re looking at what molecules are involved in the chain of events when the fiber touches the cell. Does the binding occur over minutes, or hours? And what processes are triggered?”

“The hypothesis we’re testing is that binding of cell surface receptors to asbestos fibers triggers a signal event, which initiates the cancer,” said Steven Lower, an associate professor at Ohio State University and the coauthor of the study. “There seems to be something intrinsic about certain types of asbestos, blue asbestos in particular, that elicits a unique signal, and it triggers inflammation, the formation of pre-malignant cells and, ultimately, cancer.”

The first protein (receptor) which will be examined is epidermal growth factor receptor, which is present on all human cells. The scientists hope that this will help in preventing the disease. That means that they hope to be able to “know” right after someone gets exposed to asbestos, and cure it. That’s very important, considering that asbestos causes mesothelioma thirty to fifty years after being exposed.

The research is funded by the National Science Foundation.

Scientists discover anti-tumor gene

A new anti-tumor gene called SARI has been discovered and identified by scientists from the Virginia Commonwealth University. The gene can suppress a key protein that is overexpressed in 90% of human cancers. This is a huge discovery, since this could lead to finding a working cure for cancer.

The whole project was successfully finished in the Fisher laboratory by using a technique called subtraction hybridization. Interferon was used as a immune system modulator.

The scientists delivered the gene through a virus to infected cancer cells, and they stopped dividing and died.
“Additionally, IFNs are powerful immune modulating agents that contribute to the immune response to cancer and they are effective inhibitors of new blood vessel formation, the process of angiogenesis, which is obligatory for the growth of both primary and metastatic cancers,” said Fisher, a member of VCU Massey Cancer Center.

IFNs are currently being used in treatment of many diseases, such as melanoma, malignant glioma, leukemia and more. “We have uncovered a new way by which interferon can induce anti-tumor activity. The identification of SARI also provides a new potential reagent for the selective killing of tumor cells,” said Fisher.

This work was funded by the National Institutes of Health, the Samuel Waxman Cancer Research Foundation and the National Foundation for Cancer Research.

Source: vcu.edu

Targeted nanoparticles to treat prostate cancer

A team of scientists from Massachusetts Institute of Technology (MIT) and Harvard Center for Nanotechnology Excellence, led by Lippard, Langer and Farokhzad, Ph.D.’s, have designed a nanoparticle that is able to deliver anticancer drug cisplatin to prostate cancer cells.

The nanoparticle is made out of two polymers and a nucleic acid aptamer which binds to the tumor marker antigen, which is specific for prostate. The aptamer is responsible for making the drug transferable directly and only to prostate cancer cells.

It isn’t easy to create a stable nanoparticle which is able to release it’s toxic cargo inside tumor cells. In this case, researchers used a modified version of cisplatin that contains a long hydrocarbon chain. As the nanoparticle forms, the hydrocarbon chain associates strongly with the hydrophobic chains of the polymer that forms the nanoparticle’s core. The researchers note that the hydrocarbon chain they chose optimizes both drug encapsulation and drug release inside tumor cells. Once the nanoparticle enters the cell, the modified drug is converted into its active form as a result of chemical conditions inside the cell.

Tests with human cells grown in culture showed that the nanoparticles were absorbed by the cancer cells, and not by the healthy cells.

The paper was published in Proceedings of the National Academy of Sciences of the United States of America.

Source: nano.cancer.gov/news_center/2008/nov/nanotech_news_2008-11-20b.asp

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