Generation of hydroxyl radical-activatable ratiometric near-infrared bimodal probes for early monitoring of tumor response to therapy

Tumor response to radiotherapy or ferroptosis is closely related to hydroxyl radical (center dot OH) production. Noninvasive imaging of center dot OH fluctuation in tumors can allow early monitoring of response to therapy, but is challenging. Here, we report the optimization of a diene electrochromic material (1-Br-Et) as a center dot OH-responsive chromophore, and use it to develop a near-infrared ratiometric fluorescent and photoacoustic (FL/PA) bimodal probe for in vivo imaging of center dot OH. The probe displays a large FL ratio between 780 and 1113 nm (FL780/FL1113), but a small PA ratio between 755 and 905 nm (PA(755)/PA(905)). Oxidation of 1-Br-Et by center dot OH decreases the FL780/FL1113 while concurrently increasing the PA(755)/PA(905), allowing the reliable monitoring of center dot OH production in tumors undergoing erastin-induced ferroptosis or radiotherapy. The hydroxyl radical is generated during radiotherapy and ferroptosis and accurate imaging of this reactive oxygen species may permit the monitoring of response to therapy. Here, the authors develop a ratiometric probe for accurate imaging of hydroxyl radical generation in vivo.

Automated summary

The response of tumors to radiotherapy or ferroptosis is closely linked to hydroxyl radical production, and accurate imaging of this reactive oxygen species may allow for monitoring of therapy response. A ratiometric probe has been developed for in vivo imaging of hydroxyl radical generation, providing a reliable method for monitoring treatment response in tumors undergoing erastin-induced ferroptosis or radiotherapy.