Article

Photochemical interactions of methylene blue and analogues with DNA and other biological substrates

Chemistry Department, Trinity College, Dublin, Ireland.
Journal of Photochemistry and Photobiology B Biology (Impact Factor: 2.8). 01/1993; 21:103-124.

ABSTRACT The light-induced reactions of methylene blue and related phenothiazinium dyes with biological substrates are described. The properties of the excited states of the dyes, their reactions with nucleic acids and their photosensitised chemical modifications of nucleic acid bases are examined. Reports on phenothiazinium dye-induced damage to proteins, lipids, biological membranes, organelles, viruses, bacteria, mammalian cells and carcinomas are reviewed.

1 Bookmark
 · 
174 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The recent study on binding of small molecules to double stranded DNA suggested that the intercalation of a tricyclic heteroaromatic molecule, thionine, with natural DNA provided thermal stabilization to the complex. In the present study, we reported theoretical analysis of thionine binding with Clostridium perfringenes DNA duplex (CP-DNA) by using an amended Zimm and Bragg theory, to explain the melting behaviour and heat capacity of CP-DNA with and without thionine binding. The experimental models of Paul et al. (2010) have been used for the study. The sharpness of transition has been examined in terms of half width and sensitivity parameter (∆H/σ). The results of theoretical ap-proach suggested that the various parameters such as transition profile, sharpness of the transition, heat capacity curve and half widths are in good agreement with the experimental measurements for binding of thionine. Therefore, the pro-posed theoretical analysis may be useful in order to understand interaction of small molecules to DNA that may be ap-plied in the process of drug development and for designing more potential DNA binding therapeutic molecules.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Background: Photodynamic therapy (PDT) is a method for killing cells (bacterial, fungal and cancer cells) or virus using photosensitizers (PS) and light of various wavelengths. In vitro PDT using endoscopic light against H. pylori was effective at a concentration of 0.2 mg/mL of MB. The purpose of this study was to increase the effect of photodynamic modality against H. pylori by addition of chitosan to MB. Methods: The bactericidal effect was measured by counting viable cells after PDT. The degree of damage to DNA was confirmed using alkaline gel electrophoresis. Cellular DNA damage was demonstrated by ethidium bromide monoazide quantitative polymerase chain reaction (EMA qPCR). Results: In the groups treated with either 0.04 mg/mL MB alone or 0.02 mg/mL MB with endoscopic light for 15 min, viable cells were decreased approximately tenfold. The group treated with 0.04 mg/mL of MB with light, showed more effective bactericidal activity than 0.02 mg/mL of MB treatment. By 0.05% chitosan pre-treatment followed with 0.04 mg/mL of MB and light irradiation, viable cells were decreased 10(7)-fold. The DNA damage caused by PDT as demonstrated by alkaline gel electrophoresis was greater in the MB plus chitosan-treated group than in control and MB-treated groups. Cellular DNA damage demonstrated by EMA qPCR was also greater in the group treated with MB plus chitosan than in the MB-treated group. Conclusion: The bactericidal effects with PDT using MB were increased with the concentration of photosensitizer and chitosan treatment, peculiarly before endoscopic light irradiation.
    Photodiagnosis and Photodynamic Therapy 08/2014; 11(4). DOI:10.1016/j.pdpdt.2014.08.005 · 2.52 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Photodynamic therapy (PDT) involves the cellular uptake of a photosensitizer (PS) combined with oxygen molecules and light at a specific wavelength to be able to trigger cancer cell death via the apoptosis pathway, which is less harmful and has less inflammatory side effect than necrosis. However, the traditional PDT treatment has two main deficiencies: the dark toxicity of the PS and the poor selectivity of the cellular uptake of PS between the target cells and normal tissues. In this work, methylene blue (MB), a known effective PS, combined with Au nanoparticles (NPs) was prepared using an intermolecular interaction between a polystyrene-alt-maleic acid (PSMA) layer on the Au NPs and MB. The Au@polymer/MB NPs produced a high quantum yield of singlet oxygen molecules, over 50% as much as that of free MB, when they were excited by a dark red light source at 660 nm, but without significant dark toxicity. Furthermore, transferrin (Tf) was conjugated on the Au@polymer/MB NPs via an EDC/NHS reaction to enhance the selectivity to HeLa cells compared to 3T3 fibroblasts. With a hand-held single laser treatment (32 mW/cm) for 4 min, the new Au@polymer/MB-Tf NPs showed a two-fold enhancement of PDT efficiency toward HeLa cells over the use of free MB at 4 times dosage. Cellular staining examinations showed that the HeLa cells reacted with Au@polymer/MB-Tf NPs and the 660 nm-light excitation triggered PDT, which caused the cells to undergo apoptosis (''programmed'' cell death). We propose that applying this therapeutic Au@polymer/MB-Tf nanoagent is facile and safe for delivery and cancer cell targeting to simultaneously minimize side effects and accomplish a significant enhancement of the photodynamic therapeutic efficiency towards next-generation nanomedicine development.
    ACS Applied Materials & Interfaces 12/2014; 7(1). DOI:10.1021/am5064298 · 5.90 Impact Factor

Full-text

Download
1,088 Downloads
Available from
May 20, 2014