Evaluation of photosensitizer-containing superhydrophobic surfaces for the antibacterial treatment of periodontal biofilms

Antimicrobial photodynamic therapy (aPDT) is a promising approach to control biofilms involved in periodontal diseases. However, certain challenges, such as staining of teeth, preferential interaction of photosensitizer (PS) with Gram-positive versus Gram-negative bacteria, and insufficient oxygen in hypoxic periodontal pockets have presented barriers to its use in the clinic. To overcome these challenges, a novel superhydrophobic (SH) film that generates airborne singlet oxygen has been developed. The SH-aPDT approach isolates the PS onto a topologically rough solid SH film on which channels allow air to diffuse to the PS surface, thus ensuring sufficient oxygen supply. Upon illumination, gas phase singlet oxygen (O-1(2)) is produced and diffuses from the SH surface to the underlying biofilm. The killing efficacy was assessed as a function of transmitted fluence (17.9-89.5 J/cm(2)) and chorin e6 loading (96-1110 nmol/cm(2)) by counting of colony forming units, biofilm metabolism by XTT and confocal microscopy. The decrease in viability of both Gram-positive and Gram-negative bacteria in a multi-species biofilm was found to be linearly dependent on the fluence as well as the loading of the PS up to 71.6 J/cm(2) when 1110 nmols/cm(2) of chlorin e6 was used. A > 4.6 log bacterial reduction was observed under these conditions (p < 0.05). This novel SH-aPDT approach shows promise as an effective method to disinfect multi-species bacterial biofilms associated with periodontal disease and will be evaluated in animal models in future studies.

Automated summary

Antimicrobial photodynamic therapy is a promising method for controlling biofilms in periodontal diseases. To overcome challenges such as teeth staining and lack of sufficient oxygen, a novel superhydrophobic film that generates airborne singlet oxygen has been developed. This approach shows effectiveness in disinfecting bacterial biofilms and will be further evaluated in animal models.