Mechanistic insight into graphene coatings for oral biofilm inhibition and osteoblast compatibility

Abstract

The initial adhesion of bacterial cells to implant surfaces is a critical step in the development of biofilms, complex microbial communities that are highly resistant to conventional antimicrobial treatments. Once established, these biofilms and their self-produced extracellular matrix are difficult to eradicate. As a result, there is growing interest in engineering implant surfaces that can effectively disrupt bacterial adhesion and subsequent biofilm formation. Various surface modification strategies, including antimicrobial agents and nanomaterial-based coatings, have been investigated. Among these, graphene-based coatings have shown promising antimicrobial properties. However, mechanisms of their bactericidal activity remain insufficiently understood. This study evaluates the antimicrobial efficacy of vertically aligned graphene (VG) coatings against Streptococcus mutans, employing electron microscopy and transcriptomics analysis to elucidate the mode of action. The findings demonstrate that these coatings inhibit biofilm formation through a multifaceted mechanism: (i) reducing bacterial colonization, (ii) nanoscale protrusions, and (iii) modulating the expression of genes associated with membrane integrity, transport, oxidative stress, and cell division. Importantly, the coatings inhibited bacterial adhesion and biofilm formation without affecting osteoblast growth or proliferation. These results indicate that VG coatings offer a dual benefit by enhancing antimicrobial activity while being compatible for osseointegration, making them promising candidates for next-generation biomedical implants.