Near-Infrared Dye-Loaded Thermosensitive Hydrogels as Novel Fluorescence Tissue Markers.

Area of Science:

• Biomaterials Science
• Surgical Innovation
• Medical Imaging

Background:

• Intraoperative localization of deep lesions is challenging in minimally invasive surgery.
• Current methods like ink and clips have limitations such as dye diffusion and poor visibility.
• Need for improved tissue markers for accurate lesion identification.

Purpose of the Study:

• To develop and evaluate thermosensitive injectable hydrogels for enhanced intraoperative lesion localization.
• To assess the fluorescence retention and visibility of hydrogel-based markers.
• To determine the suitability of these hydrogels for fluorescence-guided surgery.

Main Methods:

• Formulation of four thermosensitive hydrogels: HGC, Pluronic F-127, PCL-PEG-PCL, and PLA-PEG-PLA.
• Incorporation of indocyanine green-human serum albumin (ICG-HSA) complexes into hydrogels.
• Evaluation of sol-gel transition at physiological temperatures.
• In vivo fluorescence imaging to assess signal retention duration and intensity.

Main Results:

• All hydrogels showed sol-gel transitions at body temperature, enabling in situ dye entrapment.
• HGC and Pluronic F-127 hydrogels retained fluorescence for 5 and 2 days, respectively.
• Polyester-based hydrogels (PCL-PEG-PCL, PLA-PEG-PLA) provided long-term fluorescence retention (21-30 days).
• PLA-PEG-PLA exhibited superior signal-to-background ratios and sustained intensity.

Conclusions:

• Thermosensitive hydrogels incorporating ICG-HSA complexes are effective tissue markers.
• These hydrogels facilitate real-time, minimally invasive, and long-term fluorescence-guided lesion tracking.
• Polyester-based hydrogels offer promising solutions for sustained intraoperative guidance.