Photodynamic Therapy PDT

The most important application for singlet oxygen generators (SOGs), namely the anti-cancer treatment known as photodynamic therapy (PDT), is described elsewhere in this series (see Chapter 9.22). However, SOGs are also being evaluated in other areas, such as hard surface disinfectants, soaps and washing powders,73 and insecticides.74,75... 

Over the past 20 years, the principal biomedical application for (free or metal-substituted) porphyrins has been Photodynamic Therapy (PDT), with extensive literature in the area including a number of comprehensive reviews (114-116). Porphyrins offer scope for optical imaging as they are potent fluorophores in the red region of the electromagnetic spectrum. Although, to date, the emphasis has been on their therapeutic effects, due to their... 

Porphyrins and related structures have long been used in photodynamic therapy (PDT). In PDT, the photo-induced production of singlet oxygen is the toxifying... 

Dye-doped polymeric beads are commonly employed in different formats (Fig. 5), namely as water-dispersible nanosensors, labels and in composite materials (DLR-referenced and multianalyte sensors, sensor arrays, magnetic materials, etc.). The sensing properties of the dye-doped beads are of little or no relevance in some more specific materials, e.g., the beads intended for photodynamic therapy (PDT). The different formats and applications of the beads will be discussed in more detail in the following section, and the relative examples of sensing materials will be given. 

Abstract The supramolecular composites containing fullerenes C60 immobilized at nanosilica were used for the design of the molecular systems that can be an effective agent in cancer photodynamic therapy (PDT). In particular, it was shown that photoexcited fullerene C60-containing composites decrease viability of transformed cells, intensify the process of lipid peroxidation (LPO) in cell membranes and accumulation of low-molecular weight DNA fragments, and also decrease the activity of electron-transport chain of mitochondria. 

Presently photodynamic therapy (PDT) is considered as a perspective way for therapy of different diseases, including cancer. PDT is a method based on the local light-induced activation of photosensitizers able to accumulate selectively in energy-deficient cells (malignant or dysplastic ones) not influencing the remaining normal cells of the body (Pass, 1993). Upon the action of irradiation of certain wavelength characteristic for individual photosensitizer, photochemical reaction occurs... 

Work during the last ten years on photodynamic therapy (PDT) has established the methodology as effective in the early treatment of cancers, and in the treattnent of certain skin disorders and viral infections. Approval by the regulatory authorities for sensitisers in this process began in 1993 when Canada allowed the use of Photofrin (QLT Therapeutics), an action followed later by most countries around the world. Now many other companies have sensitisers at late stage clinical dials (2001), see below in Table 4.5. An excellent introduction to the chemistry of this topic is provided in the book written by Bonnett. ... 

Figure 4.21 Outline of photodynamic therapy (PDT) treatment of tumours.

Many compounds sensitize biomolecules to damage by UVA (320-380 nm) and visible light. Two general mechanisms of sensitization are encountered. The Type I mechanism involves electron or hydrogen transfer from the target molecule to the photosensitizer in its triplet state. If 02 is present, this can be reduced to 02 by the reduced sensitizer. In the Type II mechanism, the excited sensitizer is quenched by 02, which is excited to the singlet state (typically A"g) and attacks the target molecule. Photosensitization is exploited in photodynamic therapy (PDT) for the destruction of cancerous or other unwanted cells. 

The use of photochemical treatment to stimulate translocation of endocytosed macromolecules into the cytosol is a novel technology to improve therapeutic efficacy. The technology as described in this review is derived from photodynamic therapy (PDT) and is named PCI. In both cases a photosensitizer is used in combination with light to exert the treatment effects. The basic mechanisms of the photosensitizers and their tissue interaction in combination with light will be described with emphasis on the properties of the photosensitizers used in PCI before describing the use of PCI for cytosolic delivery of macromolecules. 

Photodynamic therapy (PDT) is a developing approach to the treatment of cancer and certain other diseases, such as age-related macular degeneration, which uses a combination of a photosensitizing dye and laser light to obtain a therapeutic effect [75], There is also an absolute requirement for oxygen. If any of the... 

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