Theranostic NIR-active Conjugated Polymer Nanoparticles

Conjugated polymer nanoparticles (CPNs) based on a common solar cell material (PTB7) have been prepared, and their potential in theranostic applications based on bioimaging and photosensitizing capabilities has been evaluated. The main absorption and emission bands of the prepared CPN particles both fell within the NIR-I (650-950 nm) transparency window, allowing facile and efficient implementation of our CPNs as bioimaging agents, as demonstrated in this work for A549 human lung cancer cell cultures. The prepared CPN samples were also shown to produce reactive oxygen species (ROS) upon photoexcitation in the near infrared or ultraviolet spectral regions, both in aqueous solutions and in HaCaT keratinocyte cell cultures. Importantly, we show that the photosensitizing ability of our CPNs was largely determined by the nature of the stabilizing shell: coating the CPNs with a pluronic F127 copolymer led to an improvement of photoinitiated ROS production, while using PSMA instead completely quenched said process. To best of our knowledge, this work is the first to demonstrate the modulation of the photosensitizing capability of CPNs via an appropriate selection of stabilizing material and one that opens a new gateway to the design of theranostic probes based on CPNs.