New generation ICG-based contrast agents for ultrasound-switchable fluorescence imaging

Area of Science:

• Biomedical Engineering
• Optical Imaging
• Nanotechnology

Background:

• Ultrasound-switchable fluorescence (USF) enables high-resolution, deep-tissue imaging using fluorescence contrast.
• Indocyanine green-encapsulated poly(N-isopropylacrylamide) nanoparticles (ICG-NPs) are effective near-infrared (NIR) USF contrast agents.
• First-generation ICG-NPs suffer from a limited shelf life of less than one month.

Purpose of the Study:

• To enhance the shelf life and functionality of ICG-NPs for USF imaging.
• To explore modifications for improved stability and future molecular targeting.
• To optimize imaging parameters for in vivo applications.

Main Methods:

• Development of new-generation ICG-NPs with extended shelf life (>6 months).
• Conjugation of hydroxyl or carboxyl functional groups for molecular targeting capabilities.
• Investigation of temperature-switching threshold (Tth) and background temperature (TBG) effects on USF image quality.

Main Results:

• Significantly increased shelf life of ICG-NPs to over six months.
• Successful conjugation of functional groups for potential molecular targeting.
• Demonstrated influence of Tth and TBG on USF imaging performance.

Conclusions:

• The new-generation ICG-NPs offer improved stability and versatility for USF imaging.
• Optimizing Tth around 38-40°C is crucial for effective in vivo USF imaging.
• These advancements reduce barriers to the clinical application of USF technology.