Gold Nanocluster Encapsulated Nanorod for Tumor Microenvironment Simultaneously Activated NIR-II Photoacoustic/Photothermal Imaging and Cancer Therapy

Tumor microenvironment (TME)-responsive imaging and therapy has great potential for application towards precision diagnosis and treatment of cancer. Photoacoustic (PA) imaging with the second near-infrared window (NIR-II) and photothermal therapy are important ways to address high-resolution imaging of in vivo deep tumor tissue and high-effect therapy of cancer. A gold nanocluster (AuNCs) encapsulated nanorod (AuNRs) (AuNRs@MEA/DTGA@AuNCs, hereafter AMDAs) is prepared. The AuNRs are first modified using β-mercaptoethylamine (MEA) to form AuNRs@MEA. Dithioglycolic acid (DTGA) is coupled with AuNRs@MEA to obtain AuNRs@MEA/DTGA (AMD). Finally, AuNCs are attached to AuNRs@MEA/DTGA surface to form AMDAs. In this nanocomposite materials, the encapsulation of the AuNRs by the AuNCs obscures NIR-II PA signal of AuNRs. The high expressed glutathione in the TME react with the AMDAs via redox reaction, the detachment of the AuNCs from the AuNRs surface, and detection of the NIR-II PA signal from the AuNRs, thus enabling NIR-II PA imaging of tumor tissues. In addition, due to the high intensity light absorption of AuNRs in the NIR-II region, the release of AuNRs also enhance tumor photothermal imaging and therapy. This work establishes an accurate and efficient integrated platform for nanodiagnosis and treatment of cancer.