Theranostics Platform Based on Multifunctional Au Nanocubes for an miRNA-21-Triggered Highly Efficient Tumor Imaging and Synergistic Chemo-Photothermal Therapy

The construction of a highly efficient theranostics platform is of great significance for the imaging-guided tumor treatment. In this study, a multifunctional Au nanocubes-based theranostics platform was established for amplified imaging of tumor-related miRNA-21 and synergistic chemo-photothermal therapy. For this theranostics platform, doxorubicin (Dox) was loaded in the pores of multifunctional Au nanocubes (AuNCs), and the pores were subsequently blocked via DNA locks to prevent the leakage of Dox. When the multifunctional AuNCs entered in the tumor cells, the overexpressed miRNA-21 in the tumor cells specifically initiated a cyclic chain displacement reaction, opening DNA locks with high efficiency. The opening of DNA locks led to the release of Dox from the pores of AuNCs and the aggregation of AuNCs. The released Dox was utilized for fluorescence imaging and tumor chemotherapy. The aggregated AuNCs achieved photothermal conversion under near-infrared light irradiation, which was used for photothermal therapy. The miRNA-21-triggered cyclic chain displacement reaction improves the efficiency of imaging and treatment, achieving highly sensitive and selective detection of miRNA-21 with a detection limit of 233 fM. And the combination of chemotherapy and photothermal therapy efficiently kills tumor cells both in vitro and in vivo. The multifunctional AuNCs-based theranostics platform provides an effective way to diagnose cancer and treatment.