Methods for determining the antibacterial activity of additives for polymeric materials

Four methods for assessing the antibacterial activity of natural additives with antibacterial properties intended for polymeric materials have been described: in solution, in the form of a film (agar test; bacterial culture test) and in accordance with ISO 22196. Natural additives such as berberine, quercetin, caffeic acid, curcumin and hops were tested in the form of a solution or as an additive to a polymer, i.e. poly(butylene succinate-co-adipate) (PBSA), and their activity was determined against Gram-positive and Gram-negative bacteria – S. aureus and E. coli, respectively. The best results were obtained for additives in the form of a film. On the other hand, the highest antibacterial and biocidal activity was characterized by berberine, caffeic acid and hops.