Photoactivated polycationic bioactive chitosan nanoparticles inactivate bacterial endotoxins.

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Microbiology

Background:

• Current root canal disinfection methods inadequately eliminate bacterial endotoxins (LPSs) from infected dentin.
• Bacterial endotoxins contribute to persistent inflammation and treatment failure in endodontics.

Purpose of the Study:

• To evaluate the efficacy of antibacterial photodynamic therapy (aPDT) utilizing chitosan-conjugated rose bengal nanoparticles (CSRBnps) for selective LPS inactivation.
• To assess the anti-inflammatory potential of CSRBnps in a macrophage model.

Main Methods:

• Comparative analysis of LPS neutralization by calcium hydroxide (Ca[OH]2), chitosan nanoparticles (CSnps), CSRBnps, and methylene blue (MB), with and without photoactivation.
• Assessment of inflammatory markers (nitric oxide, TNF-α, IL-6) in LPS-treated macrophage cells (RAW 267.4).
• Cytotoxicity evaluation of agents on macrophage cells using mitochondrial activity assays.

Main Results:

• CSRBnps demonstrated significant LPS inactivation and reduced expression of inflammatory markers (NO, TNF-α, IL-6).
• CSRBnps and CSnps exhibited no cytotoxicity, while MB showed minimal toxicity.
• Calcium hydroxide (Ca[OH]2) proved highly cytotoxic to macrophage cells.

Conclusions:

• Photodynamically activated CSRBnps effectively inactivate bacterial endotoxins and mitigate associated inflammatory responses.
• CSRBnps combined with photodynamic therapy present a potent strategy for endotoxin inactivation in endodontic treatments.