Gold Nanorods Electrostatically Binding Nucleic Acid Probe for In Vivo MicroRNA Amplified Detection and Photoacoustic Imaging‐Guided Photothermal Therapy

Developing a comprehensive platform which has both diagnosis and therapeutic strategies is necessary for efficient tumor treatment. In this work, a Fuel Improved microRNA Explorer (FIRE) probe with signal amplification capability is designed for sensitive detection of microRNA‐21 (miR‐21), which is upregulated in most tumor cells. Besides, FIRE could be loaded by polyethylenimine (PEI)‐modified gold nanorods (AuNR‐PEI) via facile electrostatic interaction, which could avoid the complicated processes commonly used to covalently conjugate nucleic acid probes onto AuNRs. The as‐fabricated AuNR‐PEI/FIRE system could efficiently distinguish tumor cells from non‐tumor cells. The fluorescence signals in MCF‐7 breast carcinoma and HeLa cervical carcinoma cells treated with AuNR‐PEI/FIRE are enhanced 7‐ and 4.5‐fold, respectively, compared with non‐amplification system. AuNR‐PEI/FIRE improves tumor detection ability in vivo and exhibits excellent tumor inhibition efficacy under the fluorescence imaging and photoacoustic imaging guided photothermal therapy. This is the first time to utilize the combined application of amplified nucleic acid detection and photothermal effect derived from gold nanorods together with PA imaging in a facile manner to provide a promising theranostic strategy for accurate diagnosis and tumor therapy. A novel strategy for efficient tumor theranostics is demonstrated. The system shows higher microRNA (miRNA) detection sensitivity than traditional methods. Moreover, this is the first time to simultaneously achieve amplified in vivo miRNA detection and photoacoustic imaging‐guided tumor photothermal therapy in vivo.