Department of Macromolecular Science, The State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, PR China.
Department of Chemistry, The State Key Laboratory of Molecular Engineering of Polymers, Institute of Biomedicine Science, Fudan University, Shanghai 200433, PR China.
Biomaterials. 2014 Sep;35(27):7870-80. doi: 10.1016/j.biomaterials.2014.05.054. Epub 2014 Jun 12.
Lysosomal imaging represents a potent tool for investigating the organization of related cellular events and their modulation via diagnostic and therapeutic approaches. However, specific labeling of the lysosome in live cells is a significant challenge. Taking advantage of the inherent lysosomal entry of nanoparticles and unique digestive inclusions in the lysosome, we developed a nanoparticle-based, enzyme-switchable fluorescence OFF-ON strategy for specific labeling of the lysosome and further imaging of extracellular acidification-induced lysosome trafficking in living cells. The nanoprobe comprised a 16 nm spherical gold nanoparticle as the core and an enzyme-responsive oligomer of fluorescein-conjugated oligo(4-vinyl-phenyl phosphate) as the shell. Due to quenching of the core gold nanoparticle, the nanoprobe was non-fluorescent. After incubation with cancer cells, the nanoprobe was rapidly internalized via scavenger receptor-mediated endocytosis and significantly shuffled into the lysosome. The nanoprobe specifically lighted up the lysosome owing to lysosome-induced fluorescence enhancement. Specifically, digestive inclusions in the lysosome hydrolyzed and released gold-quenched fluorescein molecules, leading to significant augmentation of fluorescence. On account of specific lysosomal labeling, the nanoprobe effectively facilitated imaging of a 4-6 μm anterograde trafficking event of the lysosome from the perinuclear region to the cell surface when an acidic extracellular environment developed. Our findings collectively highlight the use of nanoprobes for lysosomal imaging.
溶酶体成像是研究相关细胞事件的组织及其通过诊断和治疗方法进行调节的有力工具。然而，活细胞中溶酶体的特异性标记仍然是一个巨大的挑战。利用纳米颗粒内在的溶酶体进入特性和溶酶体中独特的消化内含物，我们开发了一种基于纳米颗粒的、酶响应的荧光关闭-开启策略，用于特异性标记溶酶体，并进一步在活细胞中对细胞外酸化诱导的溶酶体运输进行成像。该纳米探针由 16nm 的球形金纳米颗粒作为核心和荧光素偶联的寡聚（4-乙烯基苯膦酸）的酶响应寡聚物作为壳层组成。由于核心金纳米颗粒的猝灭，该纳米探针无荧光。孵育癌细胞后，纳米探针通过清道夫受体介导的内吞作用被迅速内化，并大量转移到溶酶体中。由于溶酶体诱导的荧光增强，纳米探针特异性地点亮了溶酶体。具体来说，溶酶体中的内含物水解并释放出金猝灭的荧光素分子，导致荧光显著增强。由于特异性的溶酶体标记，当细胞外环境呈酸性时，纳米探针有效地促进了从核周区域到细胞表面的 4-6μm 顺行转运事件的成像。我们的研究结果共同强调了纳米探针在溶酶体成像中的应用。
