Photodynamic therapy mechanism

Sessler JL, Cyr M, Maiya BG, Judy ML, Newman JT, Skiles H, Boriack R, Matthews JL, Chanh TC (1990) (Photodynamic therapy Mechanisms II) Proc SPIE Int Opt Eng 1203 233... 

W. R. Potter, SPIE Conf. on Photodynamic Therapy Mechanisms 1065,88 (1989). 

Figure 10.13 Photophysical mechanisms involved in photodynamic therapy...

Castano AP, Demidova TN, Hamblin MR (2004) Mechanisms in photodynamic therapy part one... 

Pass HI (1993) Photodynamic therapy in oncology mechanisms and clinical use. J. Natl Cancer Inst. 85 443 156. ... 

Castano AP, Demidova TN, Hamblin MR (2005) Mechanisms in photodynamic therapy Part three - Photosensitizer pharmacokinetics, biodistribution, tumor localization and modes of tumor destruction. Photodiagnosis and Photodynamic Therapy 2 91-106. 

Harrod-Kim P (2006) Tumor ablation with photodynamic therapy introduction to mechanism and clinical applications. Journal of Vascular and Interventional Radiology 17 1441-1448. 

Castano, A. P., Demidova, T. N., and Hamblin, M. R. (2004). Mechanisms of photodynamic therapy Part one—Photosensitizers, photochemistry and cellular localization. Photodiagnosis. Photodyn. Ther. 1, 279-293. 

Phenazines and their derivatives are known to be biologically significant molecules, especially in the field of photodynamic therapy. A recent example of the preparation of red shifted azine dyes potentially for photodynamic therapy was reported by Gloster and coworkers <99JHC25>. The synthesis of phenazine 171 from 170 was thought to take place through the following mechanism. 

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. 

Grant WE, Buonaccorsi G, Speight PM, et al. The effect of photodynamic therapy on the mechanical integrity of normal rabbit carotid arteries. Laryngoscope 1995 105(8 Pt I) 867-871. 

Telluroxides derived from telluropyrylium dyes can be reduced by glutathione to the parent dye (Equation 16). The reaction occurs via a two-step mechanism <1994JOC8245>. This reduction has important implications for photodynamic therapy and related oxidative chemotherapy (see Section 7.11.8). 

Oleinick NL, Evans HH. The photobiology of photodynamic therapy. Cellular targets and mechanisms. Radiat Res 1998 150 S146-S56. 

Electron transfer effects in porphyrins are of biological relevance for a number of reasons, not least in the understanding of mechanisms involved in photodynamic therapy. Studies reported include fluorescence quenching of porphyrins by oxidants such as p-benzoquinone , photoinduced electron transfer of porphyrin-acceptor molecules in solid state °, and ps experiments on quinone substituted monometallic porphyrin dimer which show evidence for super-exchange mediated electron transfer in photosynthetic systems . 

Kennedy, J.C., Marcus, S.L., and Pother, R.H. (1996) Photodynamic therapy (PDT) and photodiagnosis (PD) using endogenous photosensitizahon induced by 5-amino-levulinic acid (ALA) mechanisms and clinical results, J. Clin. Laser Med Surg., 14 289-304. 

Hematoporphyrin (HP) is widely used as photosensitizer in photodynamic therapy because of its photosensitivity. It has been successfully used in the therapy for different forms of leukemia.4 In this paper we describe the interactions between amino acids and Zn(II)-HP, Cu(II)-HP, Co(II)-HP, and Ni(II)-HP by fluorescence and absorption spectra in aqueous solution. The binding constants were calculated and the mechanism of recognition discussed. 

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