Photodynamic inactivation of bacterial biofilms on absorbable collagen membranes using indocyanine green in aqueous and hydrogen peroxide solutions.

Microbial contamination of absorbable collagen membranes used in guided bone regeneration (GBR) may compromise healing outcomes. This study aimed to investigate whether the minimum inhibitory concentration (MIC) of hydrogen peroxide (H₂O₂) can improve the antibacterial effect of indocyanine green (ICG)-mediated antimicrobial photodynamic therapy (PDT) on absorbable collagen membranes while reducing the need for high H₂O₂ concentrations. A laboratory-based model was developed using Streptococcus sanguinis and Staphylococcus aureus. The biofilms were treated with ICG (1.29 mM), H₂O₂ (at MIC), or their combination, followed by irradiation at 808 nm (12 J cm^-²) or no irradiation. The biofilm viability was assessed after treatment. PDT (ICG + 808 nm diode laser) showed a significant reduction of bacteria, which was further enhanced by the addition of H₂O₂ at MIC concentrations. Although ICG-H₂O₂-PDT showed similar efficacy to 1 M H₂O₂, this effect was dependent on light activation. Without irradiation, no comparable result was observed, emphasizing that photoactivation is essential for achieving synergistic effects with H₂O₂ at low concentration. This combination could effectively combat biofilms on collagen membranes and provide an alternative for infection control by reducing the dependence on high H₂O₂ concentrations.