Development and characterization of erythrosine nanoparticles with potential for treating sinusitis using photodynamic therapy

Background: Antimicrobial therapy for sinusitis has been shown to reduce or eliminate pathologic bacteria associated with rhinosinusitis and improve the symptoms associated with the disease. However, the continuing rise in antibiotic resistance, the ongoing problem with patient compliance, and the intrinsic difficulty in eradication of biofilms complicates antibiotic therapy. The introduction of photodynamic antimicrobial therapy (PAT) using erythrosine, a photosensitizer, could eliminate the bacteria without inducing antibiotic resistance or even requiring daily dosing. In the present study, erythrosine nanoparticles were prepared using poly-lactic-co-glycolic acid (PLGA) and evaluated for their potential in PAT against Staphylococcus aureus cells.

Methods: PLGA nanoparticles of erythrosine were prepared by nanoprecipitation technique. Erythrosine nanoparticles were characterized for size, zeta potential, morphology and in vitro release. Qualitative and quantitative uptake studies of erythrosine nanoparticles were carried out in S. aureus cells. Photodynamic inactivation of S. aureus cells in the presence of erythrosine nanoparticles was investigated by colony forming unit assay.

Results: Nanoprecipitation technique resulted in nanoparticles with a mean diameter of 385nm and zeta potential of -9.36mV. Erythrosine was slowly released from nanoparticles over a period of 120h. The qualitative study using flow cytometry showed the ability of S. aureus cells to internalize erythrosine nanoparticles. Moreover, erythrosine nanoparticles exhibited a significantly higher uptake and antimicrobial efficacy compared to pure drug in S. aureus cells.

Conclusion: In conclusion, erythrosine-loaded PLGA nanoparticles can be a potential long term drug delivery system for PAT and are useful for the eradication of S. aureus cells.