Nanobioactive glass/chitosan/collagen composite loaded with methylene blue for tissue regeneration and bacterial infection treatment by photodynamic therapy

Development of suitable tissue engineering scaffolds to be loaded with photosensitizer drugs applied in photodynamic therapy is considered a critical issue. This study we introduced new delivery system based on cerium- and silver-doped nanobioactive glass (nBG)/chitosan/collagen composite scaffolds as a carrier for a photosensitizer, methylene blue (MB), in photodynamic therapy, capitalizing on the unique photocatalytic and antibacterial properties of the doped nBG. Cerium and silver offer additional benefits in terms of antimicrobial, anticancer, and wound healing properties. MB is an effective and inexpensive therapeutic photosensitizer compound that exhibits antimicrobial activity through light activation and has shown great potential for selectively treating infected cells. The prepared scaffolds were characterized by FTIR, TGA, and SEM/EDX. The bioactivity and biodegradation were conducted in SBF. The cell viability was carried out against the WI-38 cell line. Finally, the antibacterial efficiency of scaffolds loaded with MB was evaluated before and after laser irradiation against Staphylococcus aureus, Bacillus subtilis (Gram-Positive), and Pseudomonas aerginousea, klebsiella pneumoniae (Gram-negative). Inhibition of bacteria by reactive oxygen species (ROS) was also measured. Furthermore the primarily MB release profile and kinetic were studied. The results showed that nBG particles increased the thermal stability of the scaffolds, and enhanced the formation of an apatite bone-like layer on the scaffold surfaces. Furthermore, scaffold degradation was tailored by changing the amount of nBG. Moreover, the water uptake of the scaffold containing undoped nBG particles (G010 and G020 samples) showed higher water uptake percentages (682 % and 762 %, respectively) than doped nBG (for 155 % and 322 % for GA10 and GA20, respectively). All scaffolds demonstrated good cell viability at concentrations up to 62.5 μg/ml. However, at higher concentrations, scaffolds incorporating high percentages of nBG were more viable than those containing low amounts of nBG, regardless of the glass composition. The antibacterial tests presented that the MB enhanced scaffold antibacterial efficiency by improving the oxidative stress on bacterial cells, which significantly increased after irradiation. Finally, the release mechanism of MB was diffusion mechanism for scaffolds contained nBG particles, while it did not follow this mechanism for blank polymer scaffolds. In conclusion, these results suggest that the developed multifunctional scaffolds hold significant promise for effective photodynamic antimicrobial chemotherapy in the treatment of microbial infections.