# Organic small-molecule NIR-II fluorophores for tumor phototheranostics

## TL;DR

This review discusses recent advances in small-molecule NIR-II fluorophores for deep-tissue imaging and cancer therapy, highlighting their potential for clinical use.

## Contribution

The paper provides a systematic summary of molecular engineering strategies and theranostic applications of NIR-II fluorophores over the past five years.

## Key findings

- NIR-II fluorophores enable high-resolution deep-tissue imaging with low phototoxicity.
- Recent developments include efficient photodynamic and photothermal therapeutic modalities using these fluorophores.
- Structure-function relationships and photophysical properties are key to optimizing their performance.

## Abstract

Near-infrared II (NIR-II) fluorophores possess transformative potential for biomedical applications, owing to their deep-tissue penetration, reduced tissue autofluorescence, and low phototoxicity. Recent breakthroughs in molecular engineering have accelerated the development of NIR-II organic small-molecule fluorophores based on versatile scaffolds, including cyanine, boron dipyrromethene, benzobisthiadiazole, xanthene, cyano-based derivatives, and small-molecule metal complexes. This review systematically summarizes the molecular engineering strategies, photophysical properties, and structure-function relationships of NIR-II fluorophores in the last five years. We highlight recent breakthroughs in their theranostic applications, including high-resolution deep-tissue imaging and efficient phototherapeutic modalities such as photodynamic and photothermal therapy. Finally, we present forward-looking perspectives on current challenges and emerging opportunities, aiming to provide insights for promoting continued innovation and clinical translation in this rapidly advancing field.

This review systematically summarizes the recent advances in organic small-molecule NIR-II fluorophores for phototheranostics, providing insights into further innovation and facilitating clinical translation.