A Selenium‐Substituted Heptamethine Cyanine Photosensitizer for Near‐Infrared Photodynamic Therapy

Abstract

Abstract Photodynamic therapy (PDT) is a relatively safe approach to cancer treatment without significant systemic side effects or drug resistance. However, the current PDT efficiency is unsatisfactory due to the lack of near‐infrared (NIR) photosensitizers. Heptamethine cyanine (Cy7) dyes are well‐known NIR fluorophores and are also used as photosensitizers. But their singlet oxygen quantum yields (Φ Δ ) are not ideal. Herein, we developed an NIR photosensitizer with a long‐lived excited triplet state (τ=4.3 μs) by introducing a selenium atom into the structure of a Cy7 dye. The new NIR photosensitizer exhibits a significantly high singlet oxygen quantum yield (Φ Δ =0.11). Its good PDT effect was demonstrated in the living cells. Considering that the selenium‐substituted photosensitizer has a very low dark cytotoxicity and good chemical stability, we conclude that it will have a promising future in biomedical and clinical applications.