LAUSR

The pathological progression of thyroid diseases poses a serious threat to human health. Because thyroid diseases are close-ly related to Selenocysteine (Sec), it is necessary to investigate the relationship between Sec and thyroid diseases. Herein, we design and synthesize a ratiometric near-infrared fluorescent probe (Mito-Cy-Sec) to analyze the fluctuations and roles of Sec in cells and in mice thyroid diseases model. The probe is composed of a near-infrared heptamethine cyanine fluorophore, an acrylamide as the response moiety, and a lipophilic triphenylphosphonium cation as the mitochondrial localization group. After reacting with Sec for 5 min, the probe Mito-Cy-Sec exhibits a distinct ratiometric fluorescence signal accompanied by color change from green to blue. The applicability of Mito-Cy-Sec in mitochondrial localization is assessed via the super-resolution imaging. Mito-Cy-Sec has been successfully applied to detect the fluctuations of Sec concentration in human thy-roid epithelial/cancer cell lines (Nthy-ori-3 cells/BHT101 cells) and mice thyroid diseases (thyroiditis and thyroid cancer) model. Besides, both of our probe Mito-Cy-Sec and commercial ROSGreen H2O2 probe are employed to examine the inter-relationship between H2O2 and Sec in cells and in mice models. The results demonstrate that the relevant-levels between H2O2 and Sec are exactly negative correlation. The related-levels of Sec and H2O2 may be identify as diagnostic indicators for auxiliary diagnosis of thyroid diseases. We suppose that our probe Mito-Cy-Sec can be employed as a promising chemi-cal tool for the diagnosis of thyroid diseases.