Biodegradable Biliverdin Nanoparticles for Efficient Photoacoustic Imaging.

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Optical Imaging

Background:

• Photoacoustic imaging offers deep tissue penetration but lacks biodegradable nanoparticle agents.
• Existing biodegradable nanoparticles for imaging are limited, hindering clinical translation.
• There is a need for biocompatible, metabolically digestible probes for advanced diagnostics.

Purpose of the Study:

• To develop novel biodegradable nanoparticles for photoacoustic imaging using biliverdin.
• To investigate the spectral properties and biocompatibility of these nanoparticles.
• To evaluate their efficacy in vivo for sentinel lymph node detection.

Main Methods:

• Nanoprecipitation of biliverdin cross-linked with an amine linker.
• Spectral characterization (absorbance, fluorescence) under varying synthesis conditions.
• In vivo photoacoustic imaging in mice to assess lymph node accumulation.
• Mass spectroscopy and in vivo studies to confirm biodegradation.

Main Results:

• Biliverdin nanoparticles were successfully synthesized with tunable spectral properties.
• Nanoparticles exhibited strong absorbance at 365 and 680 nm, with photoacoustic signal at near-infrared excitation.
• In vivo imaging showed accumulation in lymph nodes, indicating potential for sentinel lymph node detection.
• Complete biodegradation was confirmed in vitro and in vivo via biliverdin reductase.

Conclusions:

• Biliverdin-based nanoparticles offer a promising platform for biocompatible photoacoustic and fluorescent imaging.
• Their metabolic digestibility and inherent imaging capabilities support clinical translation.
• These nanoparticles are suitable for diagnostic imaging, particularly for sentinel lymph node mapping.