Photosensitization Reactions In Vitro and In Vivo

Abstract

This review of Photochemistry and Photobiology summarizes articles published in 2010, and highlights progress in the area of photosensitization. The synthesis of conjugated photosensitizers is an area of interest where increasing water solubility has been a goal. Targeting infrared sensitizer absorption has been another goal, and relates to the practical need of deep tissue absorption of light. Photodynamic techniques for inactivating microbes and destroying tumors have been particularly successful. Biologically, singlet oxygen [1O2(1Δg)] is an integral species in many of these reactions, although photosensitized oxidations tuned to electron- and hydrogen-transfer (Type I) give rise to other reactive species, such as superoxide and hydrogen peroxide. How photoprotection against yellowing, oxygenation, and degradation occurs was also an area of topical interest.

Scope and limitations of the TEMPO/EPR method for singlet oxygen detection: the misleading role of electron transfer

“…Its reactions include oxidation of lipids [1][2], proteins [3][4][5] and nucleic acids [6][7][8], that may trigger a biological damage. This reaction cascade can lead to undesired adverse effects, like drug-induced phototoxicity [9][10], but can also be exploited to produce beneficial effects as in photodynamic therapy [11][12].…”

Emerging Strategies for Controlling Drug Release by Using Visible/Near IR Light

“…The cyclodextrin dimer then binds to the phthalocyanine, and upon irradiation of light generates SO to cleave the vinyl dithioether bond, results in the release of the PS. Greer and co-worker also used an SO-cleavable linker for site-specific delivery of PSs (Scheme 3b) [45][46][47]. A fiber tip was conjugated to PSs through an SO-cleavable vinyl diether linker.…”

Photosensitizer and peptide-conjugated PAMAM dendrimer for targeted in vivo photodynamic therapy

“…Tumor growth was measured every day using vernier calipers, and the tumor volume was calculated by the formula (length × breadth 2 ×0.5). When tumor volume reached ~100 mm 3 , the animals were randomized into eight groups of four animals per group. Each of the four treatments was performed on two groups, and one group was subjected to PDT and the other group was considered as dark control (no PDT).…”

“…3,4 The main advantage of PDT over cancer chemotherapy is the capability to localize the treatment. By controlling light exposure to the tumor site, preferential cell death in the presence of 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphine (PS) in the targeted tissue could be achieved.…”