Förster Resonance Energy Transfer-Based Dual-Modal Theranostic Nanoprobe for In Situ Visualization of Cancer Photothermal Therapy.

The visualization of the treatment process in situ could facilitate to accurately monitor cancer photothermal therapy (PTT), and dramatically decrease the risk of thermal damage to normal cells and tissues, which represents a major challenge for cancer precision therapy. Herein, we prepare theranostic nanoprobes (NPs) for Förster resonance energy transfer (FRET)-based dual-modal imaging-guided cancer PTT, and clear visualization of the therapeutic process. The FRET-based theranostic NPs exhibit high FRET efficiency (88.2%), good colloidal stability, and tumor-targeting ability. Tumor tissue and surrounding blood vessels are visualized clearly by FRET-based NIR fluorescence imaging with a high signal-to-background ratio (14.5) and photoacoustic imaging with an excellent resolution at 24 h post injection of NPs. Under the guidance of dual-modal imaging, the NPs-induced photothermal effect selectively destructs cancer cells, simultaneously decreasing the FRET efficiency and leading to fluorescence and photoacoustic signal changes. The sensitive self-feedback process enables the in situ visualization of therapeutic process and precision guidance of in vivo cancer PTT. A high therapeutic efficacy and minimum side effects are achieved in C6 tumor-bearing nude mice, holding great promise for precision therapy and cancer theranostics.

治疗过程的原位可视化有助于准确监测癌症光热疗法（PTT），并显著降低对正常细胞和组织热损伤的风险，这是癌症精准治疗面临的一项重大挑战。在此，我们制备了用于基于Förster共振能量转移（FRET）的双模态成像引导癌症PTT以及治疗过程清晰可视化的诊疗纳米探针（NPs）。基于FRET的诊疗纳米探针表现出高FRET效率（88.2%）、良好的胶体稳定性和肿瘤靶向能力。在纳米探针注射24小时后，基于FRET的近红外荧光成像以高信噪比（14.5）以及光声成像以优异的分辨率清晰地显示肿瘤组织和周围血管。在双模态成像的引导下，纳米探针诱导的光热效应选择性地破坏癌细胞，同时降低FRET效率并导致荧光和光声信号变化。这种灵敏的自反馈过程实现了治疗过程的原位可视化以及体内癌症PTT的精准引导。在C6荷瘤裸鼠中实现了高治疗效果和最小的副作用，为精准治疗和癌症诊疗一体化带来了巨大希望。