Phototheranostics for NIR fluorescence image guided PDT/PTT with extended conjugation and enhanced TICT.

Introducing donor and acceptor into conjugated system can facilitate the intersystem crossing (ISC) rate to increase the generation of ROS. Twisted intramolecular charge transfer (TICT) state could favor enhance the nonradiative transition and photothermal conversion efficiency (PCE). Herein, diketopyrrolopyrrole (DPP) core functionalized benzene (PDDP), thiophene (TDPP), triphenylamine-conjugated benzene (TPA-PDDP) and thiophene (TPA-TDPP) derivatives were designed and synthesized. Electrochemistry experiments revealed the heavy atom effect and the introduction of triphenylamine reduced the energy level of TPA-TDPP and improved the ability to generate 1O2 (1O2 QY = 50%). In addition, in the aggregated state, introduction of thiophene, triphenylamine, and long alkyl chains promoted the twisting effect, preventing the intermolecular π-π interaction and enhancing the PCE of TPA-TDPP (38.7%). In vivo fluorescence imaging showed that TPA-TDPP NPs can target the tumor site with the enhanced permeability and retention (EPR) effect and presented excellent synergistic photodynamic/photothermal therapy.

Cell-membrane-targeted near-infrared fluorescent probe for detecting extracellular ATP.

Extracellular adenosine triphosphate (ATP) as a signal molecule plays a key role in tumor progression and metastasis. Therefore, the development of a fluorescent probe to detect extracellular ATP is crucial for tumor treatment. However, small-molecule fluorescent probes have better advantages than biological probes, such as low price, easy modification, and optical tunability, but still remain highly challenging and rarely explored in extracellular ATP detection. Here, a near-infrared small molecule fluorescent probe (NIR-P) with hydrophobic alkyl chains and hydrophilic macrocyclic polyamines was prepared for the detection of extracellular ATP. The NIR-P exhibited enhanced fluorescence upon binding to ATP by electrostatic interaction and π-π interaction between phosphates and macrocyclic polyamines, adenines and benzene rings with a limit of detection (LOD) of 21 nM. In addition, with similarity and intermiscibility to the cell membrane, the NIR-P can specifically target cell membranes and image extracellular ATP. This work provides a cell-membrane-targeted fluorescent probe used for extracellular ATP detection.