Microenvironment‐Tailored Catalytic Nanoprobe for Ratiometric NIR‐II Fluorescence/Photoacoustic Imaging of H<sub>2</sub>O<sub>2</sub> in Tumor and Lymphatic Metastasis
Tao Chen, Zhaolin Chen, Qianting Zhou, Hongye Ding, Peng Gong, Jun Wang, Huilan Cai, Rujiang Ao, Meili Yu, Jibin Song, Lisen Lin, Huanghao Yang
Abstract
Abstract In vivo H 2 O 2 visualization is crucial for disease diagnosis. Catalytic reaction‐based probes show potential in H 2 O 2 detection, yet their in vivo application remains challenging because catalysts always require a specific pH to function and cellular glutathione (GSH) may suppress signaling by depletion of hydroxyl radicals and oxidized substrates. Here, a microenvironment‐tailored catalytic nanoprobe (MTCN) comprising Fe 2+ , citric acid (CA), 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS), and downconversion nanoparticles in the liposomal cavity as well as a reference dye in the lipid membrane is reported, which utilizes the selective permeability of the liposomal membrane to offer a favorable pH for Fe 2+ catalyst with the aid of CA and to avoid GSH‐triggered signal loss by preventing entry of GSH into the cavity. The MTCN displays a large NIR‐II fluorescence (FL) ratio between 1550 and 1080 nm (FL 1550Em,808Ex /FL 1080Em,980Ex ), but a small photoacoustic (PA) ratio between 808 and 1048 nm (PA 808 /PA 1048 ). Upon exposure of MTCN to H 2 O 2 , catalytic conversion of ABTS into its oxidized form ABTS· + with 808 nm absorption causes a noticeable increment in PA 808 /PA 1048 accompanied by an apparent decrement in FL 1550Em,808Ex /FL 1080Em,980Ex , enabling bimodal ratiometric imaging of H 2 O 2 in the tumor and lymphatic metastasis.