Chitosan nanoparticle-mediated delivery of curcumin and phycocyanin for photodynamic therapy against biofilm forming bacteria

Bacteria within biofilm display resistance to host defense and conventional antimicrobial agents. The present study was aimed to reduce biofilm formation by Staphylococcus aureus and Pseudomonas aeruginosa using photodynamic therapy. Natural photosensitizers such as curcumin and phycocyanin were encapsulated within chitosan nanoparticles synthesized by ionic gelation method. It was characterized by SEM, TEM, Particle size analyzer, UV-Vis analysis, FTIR, XRD and TGA. The antibacterial activity of curcumin and phycocyanin delivered through chitosan nanoparticles against S. aureus and P. aeruginosa was investigated by well diffusion assay. Photodynamic antibiofilm activity was investigated by crystal violet assay. Generation of reactive oxygen species by photosensitizers was recorded using spectrophotometer. The chitosan nanoparticles encapsulated with photosensitizers were spherical in shape with an average size of 20 nm. Encapsulation efficiency of chitosan nanoparticles was 36.45% for phycocyanin and 44.96% for curcumin. The antibacterial and antibiofilm activity of curcumin and phycocyanin increased with concentration. Curcumin and phycocyanin reduced less than 0.5% of biofilm formed by S. aureus and P. aeruginosa in dark treatment. Illumination reduced 2.57% and 2.18% of biofilm formed by S. aureus and P. aeruginosa respectively. Photodynamic activity of curcumin and phycocyanin delivered through chitosan nanoparticles at 100 _g/mL reduced 92% and 88% of biofilm formed by S. aureus and P. aeruginosa respectively. The dose dependent photodynamic antibacterial activity was found to be mediated through the formation of reactive oxygen species. The viability of fibroblast cells was 90% in phycocyanin, 85% in curcumin, 98.5% in sham control CNPs and 88% in CNPs encapsulated with PS at 80 _g/mL. Thus, the study demonstrated the significant reduction of biofilm formed by clinical isolates through photodynamic therapy without detrimental effect to human fibroblast cells.