The photodynamic effect: the comparison of chemiexcitation by luminol and phthalhydrazide

Abstract

The presence of light, oxygen and photosensitizer (organic dye) is required for the photodynamic effect. Light and photosensitizer are harmless by themselves, but when combined with oxygen, reactive oxygen species (ROS) can be produced. This photodynamic effect is used in photodynamic therapy (PDT); the production of ROS as lethal cytotoxic agents can inactivate tumor cells. However, during PDT, there are many difficulties, so it is not possible to excite the photosensitizer using a laser, a source of light at the wavelengths specific to the photosensitizer (in visible region of the spectrum). Chemiluminescence is the light emission as a result of a chemical reaction. It is possible to use a chemiluminescent mixture to excite the photosensitizer even if the light emission does not conform to the absorption maximum of the photosensitizer. Luciferin and luminol have been used as chemiluminescent compounds (energizers) for the excitation of the photosensitizers. The aim of this work was to compare the chemiexcitation of some selected photosensitizers (e.g. fluorescein, eosin, methylene blue, hypericin and phthalocyanines) by chemiluminescent mixtures containing luminol (high chemiluminescent quantum yield) or phthalhydrazide (low chemiluminescent quantum yield) on some Gram-positive (Enterococcus faecalis, Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa, E. coli) bacteria and some cell lines (NIH3T3 and MCF7). The efficiency of the chemiexcitation was dependent on the kind of the photosensitizer and on the type of the bacterial strain or cell line and was independent of the energizers.

Chemiluminescence and Bioluminescence as an Excitation Source in the Photodynamic Therapy of Cancer: A Critical Review

“…More recently,s everalr esearchers have tried to create "selfilluminating" PDT systems based on either chemiluminescent resonance energy transfer (CRET) or bioluminescentr esonance energy transfer (BRET). [1,[7][8][9][10][11][12][13] These processes consist of nonradioactive energy transfer from chemiluminescent or bioluminescent donors to as uitable acceptorm olecule. The objective of these PDT studies is then the use of these chemi-/bioluminescent donors to activate intracellularly the PS, without the use of an external light source.…”

“…The objective of these PDT studies is then the use of these chemi-/bioluminescent donors to activate intracellularly the PS, without the use of an external light source. [1,[7][8][9][10][11][12][13] Emissiono fl ight catalyzed by an enzyme in ab iological system is known as bioluminescence( BL). [14][15][16][17][18] This is aw idespread phenomenon, and it can be observed in bacteria, dinoflagellates, worms and insects (among others).…”

“…More recently, several researchers have tried to create “self‐illuminating” PDT systems based on either chemiluminescent resonance energy transfer (CRET) or bioluminescent resonance energy transfer (BRET) . These processes consist of nonradioactive energy transfer from chemiluminescent or bioluminescent donors to a suitable acceptor molecule.…”

“…These processes consist of nonradioactive energy transfer from chemiluminescent or bioluminescent donors to a suitable acceptor molecule. The objective of these PDT studies is then the use of these chemi‐/bioluminescent donors to activate intracellularly the PS, without the use of an external light source …”

In vitroevaluation of the oxidation efficacy of transgingival photodynamic therapy

“…Neither the sensitizing dye nor the light alone has a cytotoxic effect (6). However, in appropriate doses both factors together develop the desired antibacterial properties.…”