Near-infrared (NIR) fluorescent probes can deeply penetrate through tissues with little damage. To facilitate image-guided theranostics, researchers usually apply a desired amount of photosensitizers to achieve effective photothermal responses. However, these probes could easily suffer from low photostability and aggregated-caused quenching effect in high concentrations. In this paper, the rational incorporation of an aggregated-induced emission (AIE) unit into the structure of heptamethine cyanine IR-780 is reported. Using tetraphenylethene (TPE) as an AIE core, we synthesize three TPE-modified IR-780 probes (IR-780 AIEgens) via different linkages. The IR-780 derivatives all show enhanced AIE features, in which the probe with an ether linkage (IR780-O-TPE) is superior in rapid cell uptake, high targeting capacity, and good photostability. Moreover, IR780-O-TPE exhibits the strongest cytotoxicity to HeLa cells (IC50 = 3.3 μM). The three IR-780 derivatives displayed a photothermal response in a concentration-dependent manner, in which IR-780 AIEgens are more cytotoxic than IR-780, with IC50 of 0.3 μM under 808 nm laser irradiation. In tumor-bearing mice, the optimal probe IR780-O-TPE also showed a more effective photothermal response than IR-780. By illustrating the relationship between aggregation state with photophysical properties, cell imaging, and cytotoxicity, this work is helpful in modulating NIR-based photosensitizers into AIE features for efficient image-guided theranostics.

A novel dual-channel mitochondria-targeted fluorescent probe (NCR) was rationally designed for simultaneously distinguishing and sequentially sensing H2S, Cys/Hcy, and GSH.

A customizable fluorescent probe platform that can be used to detect various bioactive analytes offers significant potential for engineering a wide range of bioprobes with diverse sensing and imaging functions. Here, we show a facile and innovative strategy for introducing cis-amino-proline as a carrier scaffold, which is appended with three specific functional groups: a target group, a water-soluble group, and fluorophores with triggers. The potency of the designed strategy could be customized to generate variable multifunctional fluorescent probes for detecting bioactive species of interest, including reactive oxygen species (ROS), reactive nitrogen species (RNS), reactive sulfur species (RSS), ROS/RSS, and even enzymes. We designed and synthesized five representative water-soluble and organelle-targeted compounds, PMB, PMN, PMD, PRB, and PME, with emission wavelengths of these fluorescent probes varying from blue to red (465, 480, 535, 550, 565, and 640 nm). This strategy could be exemplified by its application to develop a mitochondria-/lysosome-targeting multifunctional fluorescent probe capable of imaging bioactive species of interest in live cells and nude mice.

An ICT-based mitochondria-targeted fluorescent probe Mito-NP was designed and synthesized for the detection of H 2 O 2 , with radical fluorescence intensity changes (up to 120-fold) and a large Stokes shift (93 nm) in aqueous solution. There was good linear relationship (R 2 = 0.9983) between the concentration of H 2 O 2 in the range of 0 to 100 μM and the fluorescence intensity at 553 nm, with a low detection limit of 0.25 μM (S/ N = 3). Mito-NP could also visualize enzymatically generated H 2 O 2 . Furthermore, the probe could detect endogenous H 2 O 2 with good mitochondria targeting ability in living cells and could also detect the change in H 2 O 2 levels during mitochondria-oriented apoptosis. and in living cells, with good mitochondria targeting ability, and it could also detect the change in H 2 O 2 levels during mitochondria-oriented apoptosis.

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