title: Scavenger receptor-recognized and enzyme-responsive nanoprobe for fluorescent labeling of lysosomes in live cells.
abstract: 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.
authors.affiliation: Department of Macromolecular Science, The State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, PR China.
authors.forename: Yanbin
authors.initials: Y
authors.lastname: Fan
authors.affiliation: Department of Chemistry, The State Key Laboratory of Molecular Engineering of Polymers, Institute of Biomedicine Science, Fudan University, Shanghai 200433, PR China. Electronic address: fyli@fudan.edu.cn.
authors.forename: Fuyou
authors.initials: F
authors.lastname: Li
authors.affiliation: Department of Macromolecular Science, The State Key Laboratory of Molecular Engineering of Polymers, Fudan University, Shanghai 200433, PR China. Electronic address: chendy@fudan.edu.cn.
authors.forename: Daoyong
authors.initials: D
authors.lastname: Chen
mesh_terms: D000143:Acids / Q000378:metabolism; D000818:Animals; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D002470:Cell Survival; D004705:Endocytosis; D004950:Esterases / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D051116:Receptors, Scavenger / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013054:Spectrophotometry, Atomic; D013194:Staining and Labeling; D034421:Sus scrofa; D013997:Time Factors
chemical_list: D000143:Acids; D005456:Fluorescent Dyes; D051116:Receptors, Scavenger; D004950:Esterases
keywords: Enzyme; Extracellular pH; Gold; Imaging; Lysosome; Nanoparticle