Functional Photodynamic Therapy

Functional dyes (1) of many types are important photochemical sensitizers for oxidation, polymerization, (polymer) degradation, isomerization, and photodynamic therapy. Often, dye stmctures from several classes of materials can fulfiH a similar technological need, and reviewing several dye stmctures... 

This report deals with the synthesis and biological evaluations concerning photodynamic therapy properties of porphyrinyl- and dihydroporphyrinyl-type sugar derivatives. The chosen conjugates have O- and >S-glycosidic moieties or ether and ester functions. 

Intensive research interest in peripherally functionalized porphyrazines dnring the last decade has shown that these tetrapyrol derivatives shonld be considered as alternatives to the phthalocyanines that have fonnd extensive apphcations in mat r fields. These include material science and the photodynamic therapy of tnmors as well as pigments and dyes [1]. These compounds have been nsed electrophotography, optical data, photodynamic therapy of tnmois, liquid crystals, pigments and dyes. Porphyrazines have been of considerable interest to spectroscopist and theoreticians for their high symmetrical, planar stractnre and electron delocalisation [2]. 

Phototherapy is the generic term covering therapies which use light either with or without a sensitiser. Those that do not require a sensitiser use the natural chromophores within the tissue to perform this function e.g. treatment of vitamin D deficiency in rickets, and neonatal jaundice). Those that do use an added sensitiser include photochemotherapy (largely psoriasis and skin disorders) and photodynamic therapy (currently mainly cancer). Photodynamic therapy is differentiated from photochemotherapy by its additional requirement for the presence of oxygen at molecular or ambient levels.In this text we will deal only with photodynamic therapy since, at the present time, this is the main driving force in phototherapy. ° ... 

Drug and DNA delivery, photodynamic therapy, boron neutron capture therapy, and magnetic resonance imaging are some areas in which appropriately functionalized dendrimers are being evaluated (Jang and Kataoka 2005 Svenson and Tomalia 2005 Yang and Kao 2006). In one particularly nice example, polylysine... 

The ability of a range of 2,4,6-triaryl thio-, seleno- and telluro- pyrylium dyes to generate singlet oxygen and hence to function as sensitiseis for photodynamic therapy has been examined <99JMC3942,3953>. 

Functional dyes of many types are important photochemical sensitizers for chemical reactions involving oxidation, polymerization, (polymer) degradation. isomerization, and photodynamic therapy. Often, dye structures from several classes or materials can fulfill a similar technological need, particularly for laboratory or small-scale reactions where production efficiency may be of secondary importance. Commercial photochemical technology, however, is more selective and requires photochemical efficiency, ease of product separation, and lack of unwanted side reactions to an extent similar to that required by imaging processes. In addition, reusability of the spectral sensitizer is also preferred in commercial photochemical reactions. 

The reaction serves as an illustrative example of the synthetic utilization of the Te(II)—>Te(IV) two-electron shuttle. Another promising application is seen in photodynamic therapy in which tellurapyrylium dyes 119 can function as photosensitizers to produce either singlet oxygen or superoxide radical-anions (via electron transfer), thereby serving as cytotoxic agents. An important useful property of tellurapyrylium dyes is their absorbance in the near-infrared region where biological tissues are most important. 

Adili R Statius van Eps RG, Karp SJ, et al. Differential modulation of vascular endothelial and smooth muscle cell function by photodynamic therapy of extracellular matrix novel insights into radical-mediated prevention of intimal hyperplasia. J Vase Surg 1996 23(4) 698-705. 

The incorporation of pendant Pcs to a polymeric backbone via the grafting of a suitable Pc molecule to a preformed polymer containing appropriate functional groups has been accomplished by Chen and co-workers [163], These authors exploited the axial reactivity of some metalloPcs (namely, In(III)Pcs) to prepare an In(III)Pc-polystyrene copolymer. The most remarkable feature of this material is that cofacial association between the macrocycles is fully prevented. For some applications of the Pcs, such as optical limiting or photodynamic therapy (PDT), aggregation should be avoided because it produces the quenching of the excited-states. 

Brandis A, Salomon Y, Scherz A. Bacteriochlorophyll sensitizers in photodynamic therapy. In Chlorophylls and Bacteriochlorophylls Biochemistry, Biophysics, Functions and Applications. Grimm B, Porra R, Rudiger W, Scheer H, eds. 2006. Springer, Dordrecht, The Netherlands, pp. 485-494. 

Several functionalized porphycenes have been prepared in the context of generating systems that may act as photosensitizers for photodynamic therapy (PDT discussed in Chapter 10). Specific examples of systems designed for study in this area include the P-methoxyethyl-functionalized porphycenes 3.25 and 3.30 and derivatives derived therefrom (described below). A 9-acetoxy substituted system 3.94 related to... 

A.M. Fisher, A. Ferrario, N. Rucker, S. Zhang, C.J. Gomer (1999). Photodynamic therapy sensitivity is not altered in human tumor cells after abrogation of p53 function. Cancer Res., 59, 331-335. 

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