Recent advances in NIR small molecule activable probes for imaging and therapy

In the field of medical imaging and cancer treatment, the use of fluorescence (FL) methods to monitor and identify diseases is a common detection method. The function of these detection tools is to enhance the response of fluorescent signals by detecting cancer-related biomarkers to display the location of lesions in a targeted manner.

Among them, small molecule activatable probes (SMAPs) can realize the recognition function of different biomarkers by designing their molecular structures. Especially for SMAPs in the near infrared (NIR) region (900-1880 nm), compared with visible light (400–700 nm) SMAPs, NIR light has a longer wavelength, lower scattering and absorption in biological tissues, significantly better penetration depth than visible light, weak autoFL, and high imaging signal-to-noise ratio, making it suitable for deep tissue observation and high-sensitivity detection. After modification, NIR SMAPs can respond more quickly to changes in various tumors and inflammations, which are related to physiological parameters in vivo. They can accurately detect cancer metastasis and enable targeted and better treatment options, as well as improve cancer prognosis. Therefore, in this paper, we introduced the triggering mechanisms of SMAPs in the NIR-I (700–900 nm)/NIR-II (900–1880 nm) regions according to the types of different biomarkers, their applications in cancer imaging and treatment, and the emerging multimodal-guided imaging and tumor treatment regimens. Finally, the prospects and dilemmas of NIR SMAPs as further developments in the biomedical field are discussed.