Aminopeptidase N Activatable Nanoprobe for Tracking Lymphatic Metastasis and Guiding Tumor Resection Surgery via Optoacoustic/NIR-II Fluorescence Dual-Mode Imaging

Lymphatic metastasis is a crucial mechanism by which the cancer cells break away from the primary (original) tumor and travel to the closest regional lymph node(s) and ultimately to other organs or parts of the body, which is closely associated with tumor recurrence and reduced survival. Thus, tracking tumor lymphatic metastasis and realizing imaging-guided lymphoma resection surgery is of great significance. In this study, an activatable nanoprobe is developed for precisely tracking lymphatic metastasis of tumors and imaging-guided resection of the primary tumor and metastatic lymphoma. The molecular probe contains tricyanofuran as the electron-accepting unit (electron acceptor), xanthene as the electron-donating unit (electron donor), and alanine as the responsive unit (recognition moiety) for aminopeptidase N, and the probe molecules form the nanoprobe with bovine serum albumin as the matrix. The nanoprobe can respond specifically to aminopeptidase N overproduced in the tumor, thereby transmuting the alanine into an amino group, and correspondingly the nanoprobe is activated. Strong optoacoustic and NIR-II fluorescence signals emitted by the activated nanoprobe can be utilized for visualizing the lymphatic metastasis of tumors. Moreover, the nanoprobe with the aid of three-dimensional multispectral optoacoustic tomography (3D MSOT) imaging can accurately locate the tumor site of lymphatic metastasis, and ultimately, both the primary tumor and the metastatic lymphoma can be excised with resection surgery under the guidance of NIR-II fluorescence imaging.