Light-Activated Zirconium(IV) Phthalocyanine Derivatives Linked to Graphite Oxide Flakes and Discussion on Their Antibacterial Activity

Biological Performance of Hexadeca-Substituted Metal Phthalocyanine/Reduced Graphene Oxide Nanobioagents

This study presents a tetra-substituted phthalonitrile derivative, namely, diethyl 2-(3,4-dicyano-2,5-bis(hexyloxy)-6-(4-(trifluoromethoxy)phenoxy)phenyl)malonate (a), cyclotetramerizing in the presence of some metal salts. The resultant hexadeca-substituted metal phthalocyanines [M= Co, Zn, InCl)] (b-d) were used for the modification of reduced graphene oxide for the first time. The effect of the phthalonitrile/metal phthalocyanines on biological features of reduced graphene oxide (rGO) was extensively examined by the investigation of antioxidant, antimicrobial, DNA cleavage, cell viability, and antibiofilm activities of nanobioagents (1-4). The results were compared with those of unmodified rGO (nanobioagent 5), as well. Modification of reduced graphene oxide with the synthesized compounds improved its antioxidant activity. The antioxidant activities of all the tested nanobioagents also enhanced as the concentration increased. The antibacterial activities of all the nanobioagents improved by applying the photodynamic therapeutic (PDT) method. All the phthalonitrile/phthalocyanine-based nanobioagents (especially phthalocyanine-based nanocomposites) exhibited DNA cleavage activities, and complete DNA fragmentation was observed for nanobioagents (1-4) at 200 mg/L. They can be used as potent antimicrobial and antimicrobial photodynamic therapy agents as well as Escherichia coli microbial cell inhibitors. As a result, the prepared nanocomposites can be considered promising candidates for biomedicine.

Composites based on graphite oxide and zirconium phthalocyanines with aromatic amino acids as photoactive materials

This article is a part of a scientific project focused on obtaining a new type of composite materials that are characterized by singlet oxygen generation upon irradiation with red light, which can be used as antibacterial agents. The composite material is nanoscale graphite oxide (GO) particles covalently bonded to an axially substituted zirconium phthalocyanine complex. For this purpose, two phthalocyanine zirconium complexes, axially mono-substituted with 4-aminosalicylic or 4-aminophthalic acids, were prepared and measured in terms of structure, morphology, and spectroscopic properties. The zirconium phthalocyanines are photosensitizers, and the axial ligands are bridging links connecting the complexes to the GO carrier (due to their terminal amino groups and carboxyl groups, respectively). The axial ligand in zirconium phthalocyanine complexes has a strong influence on the stability and optical properties of composite materials and, consequently, on reactive oxygen species (ROS) generation. In this paper, the effect of composite components (4-aminophthalato or 4-aminosalicylato substituted zirconium phthalocyanine complex as a photosensitizer and graphite oxide as a carrier and modulator of the action of active components) on ROS generation for potential antibacterial use is discussed.

The Impact of Graphite Oxide Nanocomposites on the Antibacterial Activity of Serum

Nanoparticles can interact with the complement system and modulate the inflammatory response. The effect of these interactions on the complement activity strongly depends on physicochemical properties of nanoparticles. The interactions of silver nanoparticles with serum proteins (particularly with the complement system components) have the potential to significantly affect the antibacterial activity of serum, with serious implications for human health. The aim of the study was to assess the influence of graphite oxide (GO) nanocomposites (GO, GO-PcZr(Lys)2-Ag, GO-Ag, GO-PcZr(Lys)2) on the antibacterial activity of normal human serum (NHS), serum activity against bacteria isolated from alveoli treated with nanocomposites, and nanocomposite sensitivity of bacteria exposed to serum in vitro (using normal human serum). Additionally, the in vivo cytotoxic effect of the GO compounds was determined with application of a Galleria mellonella larvae model. GO-PcZr(Lys)2, without IR irradiation enhance the antimicrobial efficacy of the human serum. IR irradiation enhances bactericidal activity of serum in the case of the GO-PcZr(Lys)2-Ag sample. Bacteria exposed to nanocomposites become more sensitive to the action of serum. Bacteria exposed to serum become more sensitive to the GO-Ag sample. None of the tested GO nanocomposites displayed a cytotoxicity towards larvae.