Oxygen-generating Hydrogels Disrupt Periodontal Biofilms by Local Oxygen Enrichment

Abstract

Aim or Purpose: To construct injectable oxygen-generating hydrogels for O2 enrichment in local periodontal pockets and investigate their antimicrobial and antibiofilm effectiveness. Materials and Methods: Various concentrations of calcium peroxide (CPO) and 0.5 mg/mL catalase (CPO-GelMA) were encapsulated into gelatin methacryloyl (GelMA) hydrogels. Oxygen release profiles within 7 d under hypoxic conditions were measured using an optical oxygen microsensor. Antibacterial effects of different CPO-GelMA hydrogels on planktonic P. gingivalis were evaluated by growth-inhibition assay and colony-forming unit counting method. Antibiofilm effects on mono-species and multi-species biofilms (P. gingivalis, S. gordonii, F. nucleatum, A. naeslundii, and A. actinomycetemcomitans) were evaluated by confocal microscope and scanning electronic microscope (SEM). Results: Various CPO-GelMA hydrogels exhibited a burst O2 release in 30 min and sustained release for up to 7 d. 5% (wt%) or higher concentrations of CPO-loaded hydrogels possessed significant bacteriostatic effects on P. gingivalis at 24 h and 48 h, while 10% and 15% CPO-loaded hydrogels decreased the viable bacteria by 99%. Furthermore, the confocal and SEM images indicated that CPO-GelMA hydrogels substantially inhibited biofilm formation and eradicated the pre-formed mono-species and multi-species biofilms. There were more dead bacteria and less biofilm mass in the CPO-GelMA hydrogel-treated groups compared to the pure GelMA-treated one. Conclusions: Incorporating CPO into GelMA hydrogels can generate sufficient O2 for killing P. gingivalis and disrupting the pre-formed biofilms, showing promising potential as an adjunctive strategy for periodontal treatment.This study was supported by the Health and Medical Research Fund of Hong Kong (Grant number: 20190442).