Xanthene-Based Nitric Oxide-Responsive Nanosensor for Photoacoustic Imaging in the SWIR Window

Area of Science:

• Organic Chemistry
• Biomedical Imaging
• Materials Science

Background:

• Shortwave infrared (SWIR) dyes absorb light between 900-1400 nm, ideal for deep tissue imaging due to reduced light scattering and endogenous pigment interference.
• Tuning photophysical properties of near-infrared dyes offers a pathway to novel SWIR imaging agents.

Purpose of the Study:

• To develop easily synthesized SWIR xanthene dyes.
• To create a ratiometric nanoparticle for nitric oxide (NO) detection using SWIR imaging.
• To demonstrate the utility of these dyes in deep tissue photoacoustic imaging for disease models.

Main Methods:

• Synthesis of three novel SWIR xanthene dyes (SCR-1, SCR-2, SCR-3) featuring a dibenzazepine donor conjugated to thiophene, thienothiophene, or bithiophene.
• Development of a ratiometric nanoparticle (rNP-NO) by leveraging the aggregation-induced bathochromic shift of SCR-1.
• In vivo application of rNP-NO for deep tissue SWIR photoacoustic (PA) imaging in a drug-induced liver injury model.

Main Results:

• Successfully synthesized a series of easily accessible (three-step) SWIR xanthene dyes.
• Developed a ratiometric nanoparticle (rNP-NO) capable of detecting nitric oxide.
• Visualized pathological nitric oxide levels in a drug-induced liver injury model using deep tissue SWIR PA imaging.

Conclusions:

• The developed SWIR xanthene dye series is easily accessible and tunable for imaging applications.
• The ratiometric nanoparticle (rNP-NO) is effective for in vivo visualization of nitric oxide.
• This work highlights the potential of these dyes as components in nanosensor designs for deep tissue imaging studies.