The therapeutic properties of light have been known for thousands of years, but it was only in the last century that photodynamic therapy (PDT) was developed. At present, PDT is being tested in the clinic for use in oncology--to treat cancers of the head and neck, brain, lung, pancreas, intraperitoneal cavity, breast, prostate and skin. How does PDT work, and how can it be used to treat cancer and other diseases?

Photodynamic therapy for cancer

The interest in heterogeneous photocatalysis is intense and increasing, as shown by the number of publications on this theme which regularly appear in this journal, and the fact that over 2000 papers have been published on this topic since 1981. This article is an overview of the field of semiconductor photocatalysis : a brief examination of its roots, achievements and possible future. The semiconductor titanium dioxide (TiO 2 ) features predominantly in past and present work on semiconductor photocatalysis; as a result, in the most of the examples selected in this overview to illustrate various points the semiconductor is TiO 2 .

An overview of semiconductor photocatalysis

http://nathan.instras.com/MyDocsDB/doc-557.pdf

Photosensitized singlet oxygen and its applications

Heme-Containing Oxygenases

The use of lasers, over the past few decades, has emerged to be highly promising for cancer therapy modalities, most commonly the photothermal therapy method, which employs light absorbing dyes for achieving the photothermal damage of tumors, and the photodynamic therapy, which employs chemical photosensitizers that generate singlet oxygen that is capable of tumor destruction. However, recent advances in the field of nanoscience have seen the emergence of noble metal nanostructures with unique photophysical properties, well suited for applications in cancer phototherapy. Noble metal nanoparticles, on account of the phenomenon of surface plasmon resonance, possess strongly enhanced visible and near-infrared light absorption, several orders of magnitude more intense compared to conventional laser phototherapy agents. The use of plasmonic nanoparticles as highly enhanced photoabsorbing agents has thus introduced a much more selective and efficient cancer therapy strategy, viz. plasmonic photothermal therapy (PPTT). The synthetic tunability of the optothermal properties and the bio-targeting abilities of the plasmonic gold nanostructures make the PPTT method furthermore promising. In this review, we discuss the development of the PPTT method with special emphasis on the recent in vitro and in vivo success using gold nanospheres coupled with visible lasers and gold nanorods and silica-gold nanoshells coupled with near-infrared lasers.

http://wiki.phy.queensu.ca/shughes/images/0/0f/Cancer_3.pdf

Plasmonic photothermal therapy (PPTT) using gold nanoparticles

Second Generation Tumor Photosensitizers: The Synthesis and Biological Activity of Octaalkyl Chlorins and Bacteriochlorins with Graded Amphiphilic Character

β-Epimerization in the corrinoid system has recently emerged as a complicating factor in the latter stages of the total synthesis of vitamin B 12 (Eschenmoser 1971; Woodward 1973). It has also found some application in biosynthetic studies on the origin of the methyl groups in ring C (Scott, Townsend & Cushley 1973; Scott, this Discussion p. 303). This paper sets out to review briefly the β-epimerization of corrinoid polyamides, with particular reference to our work on the neo-series which provided the first established example of this phenomenon.

Neovitamin B12 (cyano-13-epicobalamin).

Recent attention has focussed on the possible value of oxygen-carrying perfluorochemical (PFC) emulsions as adjuncts to tumour destruction by photodynamic therapy (PDT; Fingar et a1 1988; Berenbaum et a1 1990). One finding from this preliminary work was that emulsified PFCs may be useful to protect skin against PDT-induced damage, although the mechanism(s) of this effect remain obscure (Berenbaum et a1 1990). We have therefore examined the effectiveness of a novel PFC emulsion in providing skin protection in mice receiving PDT.

Raymond Bonnett

Papers

Second Generation Tumor Photosensitizers: The Synthesis and Biological Activity of Octaalkyl Chlorins and Bacteriochlorins with Graded Amphiphilic Character

Neovitamin B12 (cyano-13-epicobalamin).

Assessment of a novel perfluorochemical emulsion in skin protection against photodynamic therapy in mice

Deactivation of s1 and ti states of porphyrins and chlorins upon their interaction with molecular oxygen

5,10,15,20-tetra(hydroxyphenyl)porphyrins in cancer treatment