NIR ditriphenylamine Indole-BODIPY photosensitizer: synthesis, photodynamic therapy in A549 cells and two-photon fluorescence imaging in zebrafish

In this study, the ditriphenylamine Indole-BODIPY photosensitizer T2BDP-lyso was synthesized for near-infrared photodynamic therapy and two-photon fluorescence imaging. The photosensitizer T2BDP-lyso exhibits absorption above 700 nm and emission above 800 nm, respectively. Theoretical calculations show the energy gap from the excited state S1 to the excited state T2 is 0.14 eV, which indicated that the photosensitizer T2BDP-lyso could reach the triplet state by intersystem crossing from the singlet state. Under NIR light, the singlet oxygen yield of photosensitizer T2BDP-lyso was calculated to be 0.64 in CH2Cl2. The photosensitizer T2BDP-lyso can effectively produce reactive oxygen species in A549 cells and zebrafish under 660 nm light for 5 min. The photosensitizer T2BDP-lyso exhibited lower dark toxicity and higher phototoxicity (IC50 = 1.49 μM), as well as lysosomal targeting ability (Pearson coefficient = 0.89). In the AO/EB double staining assay simulating photodynamic therapy at the cellular level, 3 μM of T2BDP-lyso light for 10 min was effective in killing cancer cells. Moreover, the photosensitizer T2BDP-lyso has a large two-photon absorption cross section at 1050 nm, which was calculated to be 138.7 GM in THF by Z-scan method, and two-photon fluorescence imaging was performed in zebrafish. The above results indicate the potential application of the photosensitizer T2BDP-lyso in near-infrared photodynamic therapy and two-photon fluorescence imaging.

Recent Advances in Chemistry, Mechanism, and Applications of Quantum Dots in Photodynamic and Photothermal Therapy

Semiconductor quantum dots (QD) are a kind of nanoparticle with unique optical properties that have attracted a lot of attention in recent years. In this paper, the characteristics of these nanoparticles and their applications in nanophototherapy have been reviewed. Phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), has gained special importance because of its high accuracy and local treatment due to the activation of the drug at the tumor site. PDT is a new way of cancer treatment that is performed by activating light-sensitive compounds named photosensitizers (PS) by light. PSs cause the destruction of diseased tissue through the production of singlet oxygen. PTT is another non-invasive method that induces cell death through the conversion of near-infrared light (NIR) into heat in the tumor situation by the photothermal agent (PA). Through using energy transfer via the FRET (Förster resonance energy transfer) process, QDs provide light absorption wavelength for both methods and cover the optical weaknesses of phototherapy agents.

Red/NIR emissive aggregation-induced emission-active photosensitizers with strong donor-acceptor strength for image-guided photodynamic therapy of cancer

Light-mediated therapies such as photodynamic therapy (PDT) are considered emerging cancer treatment strategies. However, there are still lots of defect with common photosensitizers (PSs), such as short emission wavelength, weak photostability, poor cell permeability, and low PDT efficiency. Therefore, it is very important to develop high-performance PSs. Recently, luminogens with aggregation-induced emission (AIE) characteristics and red/near-infrared (NIR) emissive have been reported as promising PSs for image-guided cancer therapy, due to them being able to prevent autofluorescence in physiological environments, their enhanced fluorescence in the aggregated state, and generation of reactive oxygen species (ROS). Herein, we developed PSs named TBTCPM and MTBTCPM with donor-acceptor (D-A) structures, strong red/NIR, excellent targeting specificities to good cell permeability, and high photostability. Interestingly, both of them can efficiently generate ROS under white light irradiation and possess excellent killing effect on cancer cells. This study, thus, not only demonstrates applications in cell image-guided PDT cancer therapy performances but also provides strategy for construction of AIEgens with long emission wavelengths.

Induced Near-Infrared Emission and Controlled Photooxidation based on Sulfonated Crown Ether in Water

Regulation of physio-chemical properties and reaction activities via noncovalent methodology has become one of increasingly significant topics in supramolecular chemistry and showed inventive applications in miscellaneous fields. Herein, we demonstrate that sulfonated crown ether can form very stable host-guest complexes with a series of push-pull-type photosensitizers, eventually leading to the dramatic fluorescence enhancement in visible and near-infrared regions. Meanwhile, severe suppression in singlet oxygen (¹ O₂ ) production is found, mainly due to the higher energy barriers between the excited single and triple states upon host-guest complexation. Moreover, such complexation-induced tuneable ¹ O₂ generation systems has been utilized in adjusting the photochemical oxidation reactions of polycyclic aromatic hydrocarbons (anthracene) and sulfides ((methylthio)benzene) in water. This supramolecularly controlled photooxidation based on the selective molecular binding of crown ether with photosensitizers may provide a feasible and applicable strategy for monitoring and modulating many photocatalysis processes in aqueous phase.