5. Antibacterial activity of nanoparticles

Bacteria are prokaryotic micro-organisms, with no organelles or nuclei. The bacterial cell is surrounded by a plasma membrane and a rigid envelope, the cell wall, which gives it its shape. A distinction is made between Gram-positive and Gram-negative bacteria on the basis of their parietal composition. The walls of Gram-positive bacteria are rich in teichoic acid and diaminopimelic acid, which are absent or less abundant in Gram-negative bacteria, whose walls are richer in lipids.

Bactericides based on silver or metal oxides have a long tradition. Colloidal silver has been used for over 50 years to minimize bacterial infections. Similarly, ZnO and MgO in their classic form are commonly used as antibacterial agents in cosmetics, food packaging and additives. Reducing the size of these particles to the nanometric scale has significantly increased their antibacterial...