Monitoring Neovascularization of Malignant Solid Tumors with Horseradish Peroxidase-Functionalized Near-Infrared-II PbS Quantum Dots

The growth and metastasis of malignant solid tumors depend closely on new blood vessels. Vasculogenic mimicry provides a special pathway of blood supply during the early growth of malignant tumors, and real-time monitoring of its occurrence and development in vivo is important to clinical applications. However, there are few labels with sufficient brightness and stability in vivo to achieve high spatiotemporal resolution imaging of deep tissue for noninvasive optical detection of vasculogenic mimicry in tumor tissues. In this study, we constructed a high-brightness fluorescent label with fluorescence in the near-infrared-II region, which can be used not only for in vivo tumor imaging but also for tissue section imaging. Real-time high-resolution imaging of tumor vessels has been achieved with PbS quantum dots (QDs) surface-coupled with horseradish peroxidase (HRP) (HRP-QDs) by taking advantage of the low background autofluorescence of tissue at the near-infrared-II wavelength for in vivo and tissue section imaging. Qualitative and quantitative analysis of early blood supply patterns of tumor growth enables monitoring neovascularization to accurate noninvasive identification of benign and malignant solid tumors.