Titanium dioxide
Antimicrobial activity can also be induced through the addition of inorganic particles such as silver, copper, and titanium dioxide nanoparticles to a polymer. Metal nanoparticles are incorporated into the polymer to form polymeric nanocomposites. Silver is utilized in antimicrobial polymers because of its stability as well as broad-spectrum antimicrobial activity. Positive silver ions are produced in environments beneficial for the growth of bacteria. These positive silver ions physically interact with cell wall proteins resulting in membrane disruption and cell death. Silver nanoparticles embedded into a cationic polymer have displayed activity against "E.coli" and "S.aureus". Copper and titanium dioxide nanoparticles are less commonly employed in antimicrobial polymers than silver nanoparticles. Copper nanoparticles embedded into polypropylene nanocomposites have demonstrated the ability to kill 99.9% of bacteria. Titanium dioxide is a nontoxic material with antimicrobial activity that is photo-activated. Titanium dioxide has been embedded in polypropylene to create photoactive antimicrobial polymers. The antimicrobial activity of the polymer composite is initiated by a light source. The light source causes the titanium dioxide to be oxidized, which results in the release of highly reactive hydroxyl species that disrupt bacteria. The effectiveness of the photoactive antimicrobial polymer has been demonstrated against the bacteria "E.coli".