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Posted on Tuesday, July 27, 2010 by admin in Internet Outage |
Tags: antibacterial residual killing, nano silver, nano silver antibacterial, sun block fabric, technology

The efficiently kill gram-negative and gram-positive bacteria in vitro. To investigate the mechanism of NK cell-mediated cytotoxicity against Escherichia coli we have developed a mathematical model of the kinetics using the experimental data. The kinetics of killing are characterized by initial target bacterial multiplication, followed by rapid bacterial death. Experiments demonstrates that for each donor there is a threshold number of effector cells necessary to observe a net killing effect.

Below the threshold, even use of high effector-to- target ratios lack killing activity and the bacterial growth cannot be stopped. In contrast, if the number of NK cells is larger than the threshold, complete killing is achieved, even at ratios as low as 1/1000.

The threshold number varies among donors, ranging between 1200 and 12000 purified NK cells/tube, and provides a quantitative measure of antibacterial activity. Performing the assay at 4 degrees C raised the threshold number required for killing. Experiments performed in Boyden chambers confirm that NK cell-bacteria contact is not necessary for efficient killing, although the kinetics of bacterial lysis is slower. The fit between model and data supports the hypothesis that the bactericidal mechanism is extracellular and is mediated by an anti- microbial

Experimental and theoretical kinetics study of antibacterial killing mediated by human natural killer cells

Light-Activated Antibacterial Coating

A new hard coating with antibacterial properties that has been tested by researchers at the UCL Eastman Dental Institute has been shown to kill 99.9% of Escherichia coli bacteria when a white hospital light was shone on its surface to activate it.

Miss Zoie Aiken and her colleagues presented the work at the Society for General Microbiology meeting in Harrogate March 31. The veneer-like surface is made of titanium dioxide with added nitrogen. When it is activated by white light, similar to those used in hospital wards and operating theatres, it produced a decrease in the number of bacteria surviving on the test surface.

The hospital environment acts as a reservoir for the microbes responsible for healthcare-associated infections (HCAI) and new ways of preventing the spread of these pathogens to patients are needed. Antibacterial coatings could be applied to frequently touched hospital surfaces to kill any bacteria present and help reduce the number of HCAI.

Titanium dioxide based coatings can kill bacteria after activation with UV light. The addition of nitrogen to these coatings enables photons available in visible light to be utilised to activate the surface and kill bacteria nano silver antibacterial residual killing.

Commenting on the results, Miss Aiken said, “The activity of the coating will be assessed against a range of different bacteria such as MRSA and other organisms which are known to cause infections in hospitals. At present we only know that the coating is active against Escherichia coli. However, E. coli is more difficult to kill than bacteria from the Staphylococcus group which includes MRSA, so the results to date are encouraging.”

“The coating has currently been applied onto glass using a method called APCVD (atmospheric pressure chemical vapour deposition),” she continued. “We are also experimenting with different materials such as plastic. As an example, the coating could be applied to a plastic sheet that could be used to cover a computer keyboard on a hospital ward. The lights in the ward will keep the coating activated, which will in turn continue to kill any bacteria that may be transferred onto the keyboard from the hands of healthcare workers.”

Source : sciencedaily / jimmunol

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