The most imperative aspect of this therapy is nontoxic nature of photosensitizers. Production of singlet oxygen is of paramount significance therefore, agents promoting the formation of singlet oxygen as well as two photons absorption are considered to be highly efficient in the therapy. Numerous receptor molecules are over-expressed in tumor cells which are of considerable importance. Peptides recognizing these receptors are conjugated with photosensitizers to reach the target cells. However, after a certain interval when photosensitizers in normal cells degenerate, the tumor cells are exposed to a particular wavelength of light which cause the excitation of the photosensitizer resulting in the formation of cytotoxic singlet oxygen. This oxygen is very reactive and cause cytotoxicity of the diseased or cancerous cells. The phenomenon is exploited in photodynamic therapy to eliminate the side-effects imposed by other cancer therapeutic measures.
Photosensitizer or photosensitizing agent is a molecule or a drug that is capable of producing a chemical alteration in another molecule or cell during the photochemical process. Photosensitizers, when exposed to a particular wavelength of light. Photosensitizers generate a form of cytotoxic oxygen that can kill the adjoining cells in the living organism. This property of photosensitizers is exploited to treat numerous superficial and localized cancers together with certain noncancerous conditions (Lau et al, 2014).
Photosensitizers are involved in medical science under the name photodynamic therapy or phototherapy, as the therapy involves insertion of certain light sensitive non-toxic chemical agents called photosensitizers, it is also known as photochemotherapy.