Composite based on graphite oxide, metallic silver and zirconium phthalocyanine coordinated by out-of-plane argininate ligands as photoactive antibacterial additive to endodontic cement

In this work, the synthesis of a group of photoactive materials based on zirconium(IV) phthalocyanine out-of-plane substituted with two fragments of L-arginine is described. The studied group contained the phthalocyanine (Pc) complex, complex immobilized on graphite oxide (GO) flakes, composite of GO-Pc with silver nanoparticles, and GO-Pc being a component of dental filling cement. The structural, compositional, morphological, and optical properties of the materials were studied using, among others, scanning electron microscopy, X-ray diffractometry, and optical spectroscopies (UV–Vis absorption, FTIR, Raman, and photoluminescence). The photoactivity of all materials was confirmed when they were exposed to broadband red light, observed as reactive oxygen species generation that was the highest for the Pc complex, lower for the GO-Pc samples, and the lowest but still present, in the case of GO-Pc-modified cement. The bioactivity of the GO-Pc and GO-Pc-Ag samples was tested against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa) bacteria strains showing the highest action against S. aureus and a slight impact of the light irradiation. The comparison of cytotoxicity tests performed for GO-Pcs with Pc complexes substituted with different ligands showed that the GO with L-arginine derivative of PcZr had the lowest toxicity.