The effect of polyhexamethylene guanidine hydrochloride on biofilm formation on polylactide and polyhydroxybutyrate composites

• The present study was aimed at investigating bactericidal properties PLA and PHB films containing PHMG derivatives and assessing bacterial biofilm formation on the surface of the films.
• The evaluation of bactericidal properties was performed for two reference bacterial strains: Escherichia coli and Staphylococcus aureus.
• According to ISO 22196, the antibacterial effects are demonstrated only by PLA and PHB containing PHMG granular polyethylene wax in the concentration of at 1%.
• The composite containing PHMG granular polyethylene wax was the strongest inhibitor of biofilm formation by S. aureus.

The aim of this study was to investigate the impact of polyhexamethylene guanidine hydrochloride (PHMG) derivatives introduced into polyhydroxybutyrate (PHB) and polylactide (PLA) on biofilm formation by Escherichia coli and Staphylococcus aureus on the surface of these composites. We also determined bactericidal activity of the applied PHMG derivatives according to standard ISO 22196. The composites were made of PLA and PHB containing PHMG stearate, PHMG granular polyethylene wax, and PHMG salt of sulfanilic acid at concentrations ranging from 0.2 to 1.0 % (w:w). The results indicate that PLA and PHB enriched with PHMG stearate and salt of sulfanic acid do not have bactericidal properties (R < 2) while PLA and PHB enriched with PHMG granular polyethylene wax have bactericidal properties (R > 2). Increased concentration of PHMG derivatives improved bactericidal activity of the investigated composites thus inhibiting biofilm formation on their surface. The composite containing PHMG granular polyethylene wax was the strongest inhibitor of biofilm formation by S. aureus.