Antibacterial photodynamic activity of photosensitizer-embedded alginate-pectin-carboxymethyl cellulose composite biopolymer films

Antimicrobial photodynamic therapy (APDT) is a promising approach for treatment of wounds infected with antibiotic-resistant bacteria. In this approach, delivery of appropriate concentration of photosensitizer (PS) at the infected site is a critical step; it is therefore essential that PS need to be administered at the infected site in a suitable formulation. Here, we report preparation of PS-embedded composite biopolymer films and their photobactericidal properties against methicillin-resistantStaphylococcus aureus(MRSA) and biocompatibility. Sodium alginate (SA), pectin (PC), and carboxymethyl cellulose (CMC) were used for preparing films containing chlorinp(6)(Cp-6, anionic PS) or methylene blue (MB, cationic PS). Films containing 1% CMC (15 mm diameter; 110 +/- 09 mu m thickness) showed similar to 55% light transmission in 500 to 750 nm region and high swelling rate as indicated by similar to 38% increase in diameter within 1 h. Absorption spectroscopic studies of PS-embedded films revealed that while Cp(6)existed mainly in monomeric state, MB existed in both dimeric and monomeric forms. MRSA incubated with the film for 1 h displayed substantial uptake of Cp-6 and MB as indicated by the presence of Cp(6)fluorescence and MB staining in cells under the microscope. Furthermore, photodynamic treatment (660 nm, 10 J/cm(2)) of MRSA with Cp-6 embedded in film or free Cp-6 resulted in similar to 3 log reduction in colony-forming units (cfu), whereas decrease in cfu was less (similar to 1 log) for MB-embedded film than for free MB (similar to 6 logs). Studies on human keratinocyte (HaCaT) cells showed that there was no significant change in the viability of cells when they were incubated with solubilized films (plain) for 24 h or subjected to treatment with PS-containing films followed by PDT. These results suggest that films are biocompatible and have potential application in photodynamic treatment of MRSA-infected wounds.

Automated summary

Antimicrobial photodynamic therapy is a promising approach for treating wounds infected with antibiotic-resistant bacteria. It involves the preparation of PS-embedded composite biopolymer films that can effectively kill MRSA and maintain biocompatibility.