Controllable Photodynamic Therapy Implemented by Regulating Singlet Oxygen Efficiency

Abstract

With singlet oxygen (1O2) as the active agent, photodynamic therapy (PDT) is a promising technique for the treatment of various tumors and cancers. But it is hampered by the poor selectivity of most traditional photosensitizers (PS). In this review, we present a summary of controllable PDT implemented by regulating singlet oxygen efficiency. Herein, various controllable PDT strategies based on different initiating conditions (such as pH, light, H2O2 and so on) have been summarized and introduced. More importantly, the action mechanisms of controllable PDT strategies, such as photoinduced electron transfer (PET), fluorescence resonance energy transfer (FRET), intramolecular charge transfer (ICT) and some physical/chemical means (e.g. captivity and release), are described as a key point in the article. This review provide a general overview of designing novel PS or strategies for effective and controllable PDT.

Spin–Orbit Charge‐Transfer Intersystem Crossing (ISC) in Compact Electron Donor–Acceptor Dyads: ISC Mechanism and Application as Novel and Potent Photodynamic Therapy Reagents

“…PDT has attracted great attention owing to its spatial and temporal selectivity, low side effects and negligible drug resistance for the treatment of tumours . Compared with traditional heavy atom‐containing PSs used in PDT, triplet PSs based on SOCT‐ISC are free of heavy atoms and therefore lower dark toxicity is expected.…”

“…Efficient production of triplet excited states in organicc ompounds upon visible light photoexcitationi so fp articulari nterest, owing to its application in photoredox catalytic preparative organic reactions, [1][2][3][4][5] hydrogen (H 2 )p roduction through photocatalytic water splitting, [6][7][8] photodynamic therapy [9][10][11][12][13][14] and triplet-triplet annihilation upconversion (TTA-UC). [15][16][17] Owingt ot he electron spin forbidden nature of the S 1 !T n transition, it is tricky to access the triplet state of an heavy atom-free organic chromophored irectly upon photoexcitation.…”

Efficient Radical‐Enhanced Intersystem Crossing in an NDI‐TEMPO Dyad: Photophysics, Electron Spin Polarization, and Application in Photodynamic Therapy

“…Photodynamic therapy (PDT), in which a photosensitizer is used to produce reactive oxygen species (ROS) and kill tumor cells upon light irradiation, has attracted tremendous attention as the next‐generation cancer treatment with a non‐invasive approach, low side‐effects, and no drug resistance . Given the high triplet state and singlet oxygen quantum yields of NDI‐TEMPO and its strong absorption of red light, we explored its potential application in PDT towards cancer cells.…”

“…Photodynamic therapy (PDT), in which ap hotosensitizer is used to produce reactive oxygen species( ROS) and kill tumor cells upon light irradiation, hasa ttracted tremendous attention as the next-generation cancert reatment with an on-invasive approach, low side-effects, and no drug resistance. [81,82] Given the high triplet state and singlet oxygen quantum yields of NDI-TEMPO and its strong absorption of red light, we explored its potentialapplicationinP DT towards cancer cells. To achieve biocompatibility and water dispersity of NDI-TEMPO,w ee n-capsulated NDI-TEMPO molecules into al iposome, aw idely used nanocarrier ford rug delivery, [83] prepared from phospholipids and cholesterol (Figure 9a).…”

Boron Dipyrromethene Nano‐Photosensitizers for Anticancer Phototherapies

“…PDT is based on the electron or energy interactions between PSs in triplet states and oxygen (O 2 ) or nearby substrates under light irradiation, generating ROS, such as free radicals (type I) and singlet oxygen ( 1 O 2 ) (type II) . When certain PSs specifically localize in tumor sites via systemic administration and are then activated by light with a specific wavelength, a series of photochemical reactions are initiated and generate ROS to inhibit tumor growth …”