Infrared fluorescence imaging of infarcted hearts with Ag₂S nanodots

Ag₂S nanodots have already been demonstrated as promising near-infrared (NIR-Ⅱ, 1.0–1.45 μm) emitting nanoprobes with low toxicity, high penetration and high resolution for in vivo imaging of, for example, tumors and vasculature. In this work, we have systematically investigated the potential application of functionalized Ag₂S nanodots for accurate imaging of damaged myocardium tissues after a myocardial infarction induced by either partial or global ischemia. Ag₂S nanodots surface-functionalized with the angiotensin Ⅱ peptide (ATⅡ) have shown over 10-fold enhanced binding efficiency to damaged tissues than non-specifically (PEG) functionalized Ag₂S nanodots due to their interaction with the upregulated angiotensin Ⅱ receptor type Ⅰ (AT1R). It is demonstrated how the NIR-Ⅱ images generated by ATⅡ-functionalized Ag₂S nanodots contain valuable information about the location and extension of damaged tissue in the myocardium allowing for a proper identification of the occluded artery as well as an indirect evaluation of the damage level. The potential application of Ag₂S nanodots in the near future for in vivo imaging of myocardial infarction was also corroborated by performing proof of concept whole body imaging experiments.