Cancerous Cell Death from Sensitizer Free Photoactivation of Singlet Oxygen

Abstract

Singlet oxygen ((1)O(2)) is an electronic state of molecular oxygen which plays a major role in many chemical and biological photo-oxidation processes. It has a high chemical reactivity which is commonly harnessed for therapeutic issues. Indeed, (1)O(2) is believed to be the major cytotoxic agent in photodynamic therapy. In this treatment of cancer, (1)O(2) is created, among other reactive species, by an indirect transfer of energy from light to molecular oxygen via excitation of a photosensitizer (PS). This PS is believed to be necessary to obtain an efficient (1)O(2) production. In this paper, we demonstrate that production of (1)O(2) is achieved in living cells from PS-free 1270 nm laser excitation of molecular oxygen. The quantity of (1)O(2) produced in this way is sufficient to induce an oxidative stress leading to cell death. Other effects such as thermal stress are discriminated and we conclude that cell death is only due to (1)O(2) creation. This new simplified scheme of (1)O(2) activation can be seen as a breakthrough for phototherapies of malignant diseases and/or as a noninvasive possibility to generate reactive oxygen species in a tightly controlled manner.

La lumière pourrait-elle traiter le cancer par interactions « lumière-vivant » ?

“…Il a été montré que cette production d'oxygène singulet est suffisante pour assurer la mort de cellules cancéreuses du sein [4].…”

The Effect of Laser Radiation at 1265 Nm on Redox-Dependent Processes in Tumor-Bearing Organisms

“…В ряде работ показана перспективность использова-ния высокоинтенсивного лазерного излучения вынужденного комби-национного рассеивания (ВКР) для лечения онкологических заболе-ваний [1][2][3]. В течение нескольких лет активно анализируется идея, согласно которой инфракрасный свет инициирует фотохимические реакции, напрямую возбуждая молекулы кислорода в биологических системах [4][5][6][7][8][9][10].…”

“…В работах [2,3] с использованием перестраи-ваемого ВКР-лазера на примере органических жидкостей и клеточных культур показано, что максимальная генерация синглетного кислорода достигается при облучении на длине волны 1264-1270 нм. Линия по-глощения О 2 в этой области спектра наиболее активна ввиду практиче-ски полного отсутствия поглощения конкурирующими хромофорами.…”

Heat shock in the springtime

“…Courtade and co-workers have created novel methods to generate heat shock (1,250 nm) or oxidant stress (1,270 nm) by laser irradiation with tight kinetic and spatial control (Anquez et al 2010;Anquez et al 2012). On the one hand, this approach allows analysis of extremely rapid (∼seconds) kinetics of activation that opens new avenues for temporal studies of stress response mechanisms.…”