Scientists at the University of South Dakota have invented a new germ-killing molecule that can be added to commercial brands of paint to give the paint long-lasting antimicrobial properties.

The molecule includes a bleach-like substance called an N-halamine. N-halamines are already used widely, but the South Dakota researchers were able to develop a new type known as Cl-TMPM.

At room temperature, Cl-TMPM is colorless oil. When droplets of Cl-TMPM are suspended in a water-based latex emulsion, the emulsion can be mixed into the paint.

In the American Chemical Society''s Applied Materials & Interfaces journal, the research team, headed by Dr. Yuyu Sun, describes experiments in which Cl-TMPM was added to latex semigloss house paint and satin latex paint.

In tests, Staphylococcus aureus organisms were killed with 10 minutes of contact, and E coli organisms were killed with 5 minutes of contact. Paint treated with Cl-TMPM was even effective against the superbug MRSA and other drug-resistant bacteria.

In addition, three months after the scientists introduced mold onto surfaces with conventional paint and Cl-TMPM paint, 100 percent of the conventional paint surface was covered with mold, whereas "no mold growth could be detected" on the Cl-TMPM surface.

Antimicrobial paints that are on the market now are only effective against a narrow range of organisms, the researchers say. Cl-TMPM, however, simultaneously protects against bacteria, viruses, mold, and fungi.

The antimicrobial potency of the new paints lasted for more than 1 year, the scientists report. Furthermore, potency can be monitored with a simple test. When effectiveness begins to wear off, or after challenging conditions, such as flooding, washing the painted surface with a re-bleaching solution restores the potency. "The antimicrobial function was fully rechargeable," the scientists report.

Paint that contains the new germ-killing compound, they conclude, has "great potential" for use in residential, commercial, institutional, industrial, and hygienic applications to reduce the risk of microbial contamination.