Nanoparticles used to break up plaque and prevent cavities.

A new strategy published in the journal Biomaterials shows how University of Pennsylvania researchers have adopted a more sophisticated approach to fight plaque.An iron oxide nanoparticle applied to teeth prior to treatment with hydrogen peroxide effectively reduced the onset and severity of cavities .The bacteria that live in dental plaque and contribute to tooth decay often resist traditional antimicrobial treatment, as they "hide" within a sticky biofilm matrix, a glue-like polymer scaffold. The team did not apply an antibiotic to the teeth rather, they took advantage of the pH-sensitive and enzyme-like properties of iron-containing nanoparticles to catalyze the activity of hydrogen peroxide, a commonly used natural antiseptic. The activated hydrogen peroxide produced free radicals that were able to simultaneously degrade the biofilm matrix and kill the bacteria within, significantly reducing plaque and preventing the tooth decay, or cavities, in an animal model. The paper's lead author was Lizeng Gao, a postdoctoral researcher in Koo's lab. Coauthors were Yuan Liu, Dongyeop Kim, Yong Li and Geelsu Hwang, all of Koo's lab, as well as David Cormode, an assistant professor of radiology and bioengineering with appointments in Penn's Perelman School of Medicine and School of Engineering and Applied Science, and Pratap C. Naha, a postdoctoral fellow in Cormode's lab. A very low concentration of hydrogen peroxide in the process was incredibly effective at disrupting the biofilm but the adding nanoparticles increased the efficiency of bacterial killing more than 5,000-fold.