# A novel near-infrared II viscosity-responsive probe for surgical fluorescence guidance: laboratory investigation in a murine subcutaneous glioma model

## TL;DR

A new fluorescent probe called POH was tested in a mouse model to help surgeons better identify brain tumor boundaries during operations.

## Contribution

The study introduces a novel NIR-II viscosity-responsive fluorescent probe, POH, with improved performance over existing agents for glioma surgery guidance.

## Key findings

- POH showed strong photostability, a large Stokes shift, and high responsiveness to tumor tissue.
- Statistical analysis showed POH outperformed ICG in delineating glioma margins and improving postoperative survival.
- The probe's semi-cyanine structure suggests potential for improved surgical navigation contrast agents.

## Abstract

Distinguishing brain tumor boundaries from surrounding parenchymal tissue with high sensitivity and specificity remains a daunting clinical challenge due to their diffuse nature and proximity to critical brain regions. Currently approved clinical fluorescent contrast agents are insufficient for clearly delineating the margins of gliomas. This study evaluated a novel near-infrared II (NIR-II) viscosity responsive fluorescent probe, POH, for fluorescence guided surgery in glioma models. Compared to commercial dyes, this probe offers advantages such as strong photostability, large Stokes shift, and high responsiveness to tumor tissue. Statistical analysis of postoperative survival and tissue margins demonstrated that the viscosity responsive probe POH exhibited significant advantages over the mainstream NIR contrast agent ICG. The unique chemical structure of this semi-cyanine derivative offers potential advantages for fluorescence guided surgery of gliomas, providing new insights into the design and selection of surgical navigation contrast agents. However, it should be noted that the subcutaneous glioma model used in this study does not replicate the intracranial tumor microenvironment or the impact of the blood-brain barrier. Future studies using orthotopic glioma models are essential to fully evaluate the translational potential of POH.