Biological effects and safety of oligo-p-phenylene vinylene photosensitizer

Abstract

Bacterial infections, particularly those associated with biofilms, represent a significant health challenge, exacerbated by the rise of antibiotic resistance. Caries and root canal infections, often caused by bacteria like Streptococcus mutans (S. mutans) and Enterococcus faecalis (E. faecalis), exemplify the difficulties in treating biofilm-related infections. S. mutans, a key contributor to caries, forms robust biofilms on tooth surfaces, while E. faecalis is notorious for its persistence in root canals, forming biofilms that are notoriously difficult to eradicate. Conventional treatment approaches, such as the use of chlorhexidine or sodium hypochlorite, often fall short due to their limited efficacy against biofilms and their potential for cytotoxicity, indiscriminately affecting both bacterial and host cells. This study investigates the potential of oligo-p-phenylene vinylene (OPV), an organic semiconductor material, as a novel photodynamic therapy agent for eradicating these infections. OPV exhibits a unique ability to selectively target and eliminate bacteria within biofilms. Its conjugated backbone, intertwined with ionic imidazole side chains, facilitates membrane binding and ensures specificity toward bacterial cells. Notably, OPV remains inert in the absence of light and exerts bactericidal effects upon activation by light, particularly blue light; it is commonly used in dental procedures. This light-activated bactericidal effect distinguishes OPV from traditional antibiotics and photosensitizers, offering a more targeted and controlled approach to bacterial eradication while minimizing damage to the surrounding healthy tissues. This study demonstrates the efficacy of OPV at eradicating S. mutans and E. faecalis biofilms under blue light irradiation. The photodynamic process involves the generation of reactive oxygen species (ROS) upon light activation, leading to bacterial inactivation without harming the surrounding healthy tissues. This targeted approach minimizes the collateral damage often associated with conventional photodynamic therapies. Furthermore, the study confirmed the low cytotoxicity of the OPV toward mammalian cells, highlighting its safety profile for clinical applications. This finding is particularly significant as it suggests the potential of OPV for treating various bacterial infections, including those resistant to traditional antibiotics, without causing any adverse effects on the host. In conclusion, this study not only reveals the potent antibacterial properties of OPV but also underscores its potential as a safe and effective treatment for caries and root canal infections. By effectively targeting and eradicating bacteria within biofilms, OPV offers a promising alternative to conventional treatment modalities, thereby addressing the growing concern regarding antibiotic resistance. This study bridges the gap between materials science and microbiology and paves the way for innovative therapeutic strategies against challenging bacterial infections.