Abstract
In search of an effective antibacterial agent that is useful in photodynamic therapy, new derivatives of zirconium(IV) phthalocyanine (ZrPc) complexes were obtained and linked to graphite oxide flakes. In the syntheses of ZrPc derivatives, two bis-axially substituted ligands with terminal amino group and different lengths of linear carbon chain (C4 in 4-aminobutyric acid or C11 in 11-aminoundecanoic acid) were used. The optical properties (absorption and photoluminescence spectra) of ZrPcs and the composites were examined. Broadband red–near-infrared lamp was tested as an external stimulus to activate ZrPcs and the composites. Optical techniques were used to show generation of singlet oxygen during irradiation. Considering the application of graphite oxide-based materials as bacteriostatic photosensitive additives for endodontic treatment of periapical tissue inflammation, the antibacterial activity was determined on one Escherichia coli strain isolated directly from an infected root canal of a human tooth and one strain with silver and antibiotic resistance. Looking at the obtained results, modified levels of activity toward different bacterial strains are discussed.
Highlights
Active phthalocyanine (Pc) systems possess intense absorption bands and exhibit photoluminescence from the excited states
Relatively high solubility of chosen Pcs complexes in water or dimethyl sulfoxide (DMSO) can be expected without additional lateral substitution with hydrophilic moieties, as proposed for most known Pc-based photodynamic therapy (PDT) agents
Lability of the system may cause the phthalocyanine ring itself to be attached to the carrier or other phthalocyanine rings
Summary
Active phthalocyanine (Pc) systems possess intense absorption bands and exhibit photoluminescence from the excited states. They are very stable and resistant to chemical, Appl. Sci. 2019, 9, 4447 thermal, or photochemical degradation. It is interesting that they act as effective photosensitizers Following their irradiation, singlet oxygen is generated, which is used in photodynamic therapy (PDT) to kill selected cells [1,2,3]. Singlet oxygen is generated, which is used in photodynamic therapy (PDT) to kill selected cells [1,2,3] This kind of activity can be used against microbial cells. Nyamu et al [4] reviewed antibacterial efficacy of phthalocyanines and noticed that Gram-positive bacteria are more sensitive to phthalocyanines than Gram-negative bacteria
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