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[Display omitted] • Two lipid-droplets (LDs) targeting photosensitizers (C-S-2 and C-S-3) were designed and synthesized. • C-S-2 and C-S-3 presented NIR emission and singlet oxygen generation capability under laser irradiation. • C-S-3 processed better photostability, superior LDs targeting capability and stronger photodynamic effect than C-S-2. The development of photosensitizers (PSs) with subcellular targeting capability has raised interest for photodynamic therapy (PDT) research. In this work, two coumarin-based photosensitizers (C-S-2 and C-S-3) were designed and synthesized via expanding their π-conjugation, introducing strong electron-donor and acceptor groups, and adopting sulfur substitution strategy. These sulfured-coumarins exhibited near-infrared emission (greater than 650 nm), lipid droplet-targeting ability and obvious photocytotoxicity under laser irradiation. In particular, C-S-3 exhibited better photostability, superior lipid droplet-targeting capability, and stronger photodynamic effect on cancer cells than C-S-2. [ABSTRACT FROM AUTHOR]

Hydrogen peroxide (H 2 O 2) as an important reactive oxygen species (ROS) is correlated in various oxidative stress and cell signaling processes. Thus, developing an effective method that can monitor H 2 O 2 in the Golgi apparatus is of great importance. Herein, a Golgi-targeting two-photon fluorescent probe (GT-H 2 O 2) that can be excited by a femto-second pulse (760 nm) is designed. GT-H 2 O 2 utilized aminoquinoline as a fluorophore / Golgi-targetable unit and borate ester as a H 2 O 2 -responsive unit with an intramolecular charge transfer strategy. The borate ester of GT-H 2 O 2 was oxidized by H 2 O 2 selectively to afford a new fluorescent molecule GT-NH 2 , thereby realizing a ratiometric detection of H 2 O 2. The probe exhibited a high sensitivity and selectivity to H 2 O 2 with a linear range from 5 to 60 μM. In addition, endogenous / exogenous H 2 O 2 could be directly visualized utilizing GT-H 2 O 2 in vitro and in vivo by one/two-photon microscopy. • A two-photon fluorescent probe (GT-H 2 O 2) is presented to sense H 2 O 2 levels. • GT-H 2 O 2 exhibited a rapid and notable ratiometric fluorescent response for H 2 O 2. • GT-H 2 O 2 can achieve Golgi localization. • GT-H 2 O 2 was visualized to monitor endogenous/exogenous H 2 O 2 by two-photon imaging. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs) have emerged as promising nanomaterials for bioimaging-guided photodynamic therapy (PDT). However, designing red-emissive CDs (RCDs) with tunable type I and type II reactive oxygen species (ROS) generation to simultaneously meet PDT applications in aerobic and hypoxic scenarios still remain major challenges. Herein, three types of RCDs with maximum emission at approximately 680 nm are successfully prepared. It is noteworthy that they exhibit the adjustable ROS production with equal superoxide anion (via type I PDT) and incremental singlet oxygen (via type II PDT). Detailed structural and optical characterizations along with theoretical calculation reveal that the unique type I/II ROS formation mainly depends on the core sizes and surface states of RCDs, which determine their identical redox potentials and tapering energy gaps between singlet- and triplet states, respectively. Additionally, due to the inherent mitochondria targeting capability, RCDs enable themselves to induce cell programmed death via activating mitochondrion-mediated apoptotic pathways. This work exploits the unprecedented RCDs with tunable type I and type II ROS generation that could ensure highly efficient tumor eradication both in vitro and in vivo, even under the harsh tumor microenvironment, providing a new prospect for CDs as nanophotosensitizers to conquer the limitations of single type PDT. Red emissive carbon dots with tunable reactive oxygen species generation are prepared to achieve highly efficient fluorescence imaging-guided type I/II photodynamic therapy via activating mitochondrion-mediated apoptotic pathways of cancer cells, providing a new prospect for carbon dots as nanophotosensitizers to conquer the limitations of single type PDT. [Display omitted] [ABSTRACT FROM AUTHOR]

Benzopyran nitrile dyes cannot be used as qualified photosensitizers due to the low quantum yield of triplet state. The benzopyran derivatives containing selenium instead of oxygen atom based on the heavy atom effect are expected to become potential agents for photodynamic therapy. In this paper, a series of selenium-containing photosensitizers (PS X) were prepared according to this strategy. PS X can effectively produce both singlet oxygen and superoxide anions upon laser irradiation. PS X exhibited the emission wavelength at 500–800 nm and near-infrared (NIR) fluorescence imaging in HeLa cells. Excellent biocompatibility and phototoxicity further indicated that PS X could be used as efficient photosensitizers for NIR fluorescence imaging and photodynamic therapy. Four novel selenium-containing photosensitizers (PS X) have been synthesized through a strategy of introducing Se into the dye core. PS X can serve as effective photosensitizers for NIR fluorescence imaging and photodynamic therapy. [Display omitted] • Four selenium-containing photosensitizers (PS X) were prepared by introducing Se into the dye core. • PS X can effectively produce both singlet oxygen and superoxide anions upon laser irradiation. • PSx exhibited near-infrared fluorescence imaging and efficient photodynamic therapy in HeLs cells. [ABSTRACT FROM AUTHOR]