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New system detects small samples of viruses
Scientists and engineers from Lawrence Livermore and the University of California (UC) at Davis have developed a system that can detect viruses in samples 1 million times smaller than those required by current commercial instruments and with about half of the analytical steps. The team’s microfluidic system permits polymerase chain reaction (PCR) analysis—or DNA copying—to be performed inside 10-picoliter droplets (about 10 trillionths of a liter) on a silicon chip.

Using the PCR-on-a-chip system, the team has analyzed hundreds of droplets in tests, demonstrating that the core technology works. The microfluidic system reduces the number of PCR heating and cooling cycles required for detecting a pathogen from 40 to about 20.

“Our goal is to take a sample that contains lots of viruses and break it down into small droplets, each of which contains no more than a single virus,” says biomedical engineer Bill Colston, who leads Livermore’s Chemical and Biological Countermeasures Division. “Then we can individually analyze all of the droplets that have viruses.” The team also wants to develop assays that detect newly emerging or unknown viruses.

This project is part of a larger Livermore-funded effort, called the Viral Discovery Platform, to identify emerging, engineered, or unknown viral threats in days rather than weeks or months. Results from the team’s research were featured on the cover of the November 15, 2007, issue of Analytical Chemistry.
Contact: Bill Colston (925) 423-0375 (bcolston@llnl.gov).

Unraveling the behavior of detonating explosives
Although high explosives have been used for more than a century, little is known about their microscopic properties during detonation. To improve understanding of this physical process, researchers from Livermore and the Massachusetts Institute of Technology have created a quantum molecular dynamics simulation of a shocked explosive near detonation conditions. The research, which was funded by Livermore’s Laboratory Directed Research and Development Program, provides the first “observation” of material behavior behind a detonation shock wave.

The simulation modeled nitromethane, an optically transparent and electrically insulating high explosive that is more energetic than TNT. Results showed that, behind the shock wave, nitromethane becomes optically reflective and semimetallic for a short time and then transforms back into a transparent, insulating material. The quantum molecular dynamics simulation of nitromethane serves as the first step in understanding molecular properties of shocked explosives at detonation conditions.

The research team, led by Livermore scientist Evan Reed, published its results in the January 2008 edition of Nature Physics. “We are continuing work to improve these capabilities,” says Reed. “Ultimately, we want to create simulations that can analyze the detonation properties of new, yet-to-be synthesized designer explosives.”
Contact: Evan Reed (925) 424-4080 (reed23@llnl.gov).

Grant boosts work on point-of-care diagnostics
Lawrence Livermore and the UC Davis Health System have teamed up to develop point-of-care diagnostic instruments for use in hospitals, rural areas, and disaster sites. Through a five-year, $8.5 million grant from the National Institute of Biomedical Imaging and Bioengineering, the team will develop two prototype instruments that simultaneously detect five bacterial and fungal pathogens: Methicillan-resistant Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Streptococcus pneumoniae, and Candida yeast infections.

Livermore chemist Ben Hindson and chemical engineer John Dzenitis direct the grant work at the Laboratory. “We see these technologies as helping medical personnel make fast, accurate diagnoses, so they can administer the proper medicine and save lives during natural disasters,” says Hindson. In collaboration with UC Davis researchers, Livermore’s Pathogen Informatics Group will develop unique DNA signatures or assays for use with the new instruments. The instruments will process blood samples using a new method called loop-mediated amplification and will run a simultaneous test for all five pathogens in one hour. Eventually, the team wants the instruments to process several samples within an hour.

Other Livermore-developed biodetection technologies, such as the Autonomous Pathogen Detection System, will provide technologies for the new instruments, which must be easy to use and require minimal user training. To help prepare the nation for disasters, the Livermore–UC Davis team will also evaluate exploratory diagnostic technologies.
Contact: Ben Hindson (925) 423-8667 (hindson1@llnl.gov).


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