A multifunctional carbon dots with near-infrared fluorescence for Au3+/Hg2+ and GSH detection and tumor diagnosis

In recent years, carbon dots (CDs) have shown potential applications in fluorescence tracing and imaging due to their excellent optical and chemical properties. In this work, a new type of carbon dots (Cy7-CDs) with near-infrared absorption and emission was synthesized from cyanine dyes and polyethylene glycol by hydrothermal reaction. The prepared Cy7-CDs exhibited low toxicity and excellent biocompatibility, which were applied to detect the noble metal ions Au3+/Hg2+ and glutathione via the ‘on–off-on’ mode. In addition, in vivo fluorescence images demonstrated that Cy7-CDs could efficiently accumulate in the tumor. Therefore, Cy7-CDs could act as a multi-functional probe for biological sensing and tumor diagnosis.