Science / Technology
Cool Plasma Pack Heat Against Biofilms
- The plasma probe is applied to an extracted tooth.
By Beth Dunham on June 5, 2009 2:15 PM
Though it looks like a tiny purple blowtorch, a pencil-sized plume of plasma on the tip of a small probe remains at room temperature as it swiftly dismantles tough bacterial colonies deep inside a human tooth.
It’s not another futuristic product of George Lucas’ imagination - it’s the exciting work of USC School of Dentistry and USC Viterbi School of Engineering researchers looking for new ways to safely fight tenacious biofilm infections in patients.
Two of the study’s authors are Chunqi Jiang, a research assistant professor in the Ming Hsieh Department of Electrical Engineering-Electrophysics, and Parish Sedghizadeh, assistant professor of clinical dentistry and director of the USC Center for Biofilms. “Nanosecond Pulsed Plasma Dental Probe” appears in the June issue of Plasma Processes and Polymers.
Sedghizadeh explained that biofilms are complex colonies of bacteria suspended in a slimy matrix that grants them added protection from conventional antibiotics. Biofilms are responsible for many hard-to-fight infections in the mouth and elsewhere. But in the study, biofilms cultivated in the root canal of extracted human teeth were easily destroyed with the plasma dental probe, as evidenced by scanning electron microscope images of near-pristine tooth surfaces after plasma treatment.
Plasma, the fourth state of matter, consists of electrons, ions and neutral species and is the most common form found in space, stars and lightning, Jiang said. But while many natural plasmas are hot, or thermal, the probe developed for the study is a non-thermal, room-temperature plasma that’s safe to touch. The researchers placed temperature sensors on the extracted teeth before treatment and found that the temperature of the tooth increased just five degrees after 10 minutes of exposure to the plasma, Jiang said.
The cooler nature of the experimental plasma comes from its pulsed power supply. Instead of employing a steady stream of energy to the probe, the pulsed power supply sends 100-nanosecond pulses of several kilovolts to the probe once every millisecond, with an average power less than two watts, Jiang said.
“Atomic oxygen [a single atom of oxygen, instead of the more common O2 molecule] appears to be the antibacterial agent,” according to plasma emission spectroscopy obtained during the experiments, she said.
Sedghizadeh said the oxygen-free radicals might be disrupting the cellular membranes of the biofilms in order to cause their demise and that the plasma plume’s adjustable, fluid reach allowed the disinfection to occur even in the hardest-to-reach areas of the root canal. Given that preliminary research indicates that non-thermal plasma is safe for surrounding tissues, Sedghizadeh said he was optimistic about its future dental and medical uses.
“Plasma is the future,” Sedghizadeh said. “It’s been used before for other sterilization purposes but not for clinical medical applications, and we hope to be the first to apply it in a clinical setting.”
“We believe we’re the first team to apply plasma for biofilm disinfection in root canals,” Jiang added. “This collaboration is unique. We’re attacking frontier problems, and we’re happy to be broadening our fields.”
Latest Science / Technology stories
- Fasting Weakens Cancer in Mice February 8, 2012 11:40 AM
- Delving Into the Emotion of Gratitude February 1, 2012 12:58 PM
- Tough Assignment for a Top Team January 31, 2012 1:36 PM
-
For Journalists »
-
USC in the News
for 2/8/2012 »-
The Chronicle of Higher Education mentioned USC’s $6 billion fundraising campaign. The story noted that USC had already raised $1 billion in a “quiet phase,” including the $200 million naming gift from USC Trustee and alumnus David Dornsife and wife Dana Dornsife to the USC Dornsife College.
The Guardian (U.K.) highlighted two major gifts to USC in a list of the 10 biggest philanthropic benefactors in America. The list included the $200 million naming gift from USC Trustee and alumnus David Dornsife and wife Dana Dornsife to the USC Dornsife College, and the $110 million gift from USC Trustee and USC Viterbi School alumnus John Mork and wife Julie to create the USC Mork Family Scholars Program.
The New York Times featured the USC U.S.-China Institute documentary “Assignment: China — The Week that Changed the World.” The documentary, part of a series, examines media coverage of the 1972 Nixon trip that reshaped U.S.-China relations after a quarter century of isolation and hostility. “People look back now and take it for granted that the outcome was preordained,” said the institute’s Mike Chinoy, who produced the documentary. Voice of America also featured the story.
Los Angeles Times featured the Oscar Senti-meter, a tool developed by the USC Annenberg School, Los Angeles Times and IBM that analyzes thousands of tweets about the Academy Awards nominees. The story noted that Mexican actor Demian Bechir received an enormous boost on Twitter the day of the nominations, with a total of 6,893 tweets mentioning him, a 47-fold increase from the day before. The story noted the tool uses language-recognition technology developed in collaboration with USC Viterbi School’s Signal Analysis and Interpretation Lab.
The Times of India (India) featured a three-day medical emergency training workshop organized in association with USC. At the workshop, held at GCS Medical College in India, 50 doctors and more than 100 paramedics learned how to improve emergency support systems. William Mallon of the Keck School of USC said that discussion topics included the use of portable ultrasonic devices to scan patients. “The ultrasound applications help physicians make accurate and timely decisions,” he noted. Daily News & Analysis (India) also featured the workshop.
-
-
Campus News
- Capital Connections
- USC faculty, staff and alumni in Washington, D.C., and Sacramento
- In Print
- New and recent books written or edited by USC faculty and staff
- Family Matters
- Achievements and awards
- Obituaries