title: Dual-Color Fluorescence Imaging of Magnetic Nanoparticles in Live Cancer Cells Using Conjugated Polymer Probes.
abstract: Rapid growth in biological applications of nanomaterials brings about pressing needs for exploring nanomaterial-cell interactions. Cationic blue-emissive and anionic green-emissive conjugated polymers are applied as dual-color fluorescence probes to the surface of negatively charged magnetic nanoparticles through sequentially electrostatic adsorption. These conjugated polymers have large extinction coefficients and high fluorescence quantum yield (82% for PFN and 62% for ThPFS). Thereby, one can visualize trace amount (2.7 μg/mL) of fluorescence-labeled nanoparticles within cancer cells by confocal laser scanning microscopy. Fluorescence labeling by the conjugated polymers is also validated for quantitative determination of the internalized nanoparticles in each individual cell by flow cytometry analysis. Extensive overlap of blue and green fluorescence signals in the cytoplasm indicates that both conjugated polymer probes tightly bind to the surface of the nanoparticles during cellular internalization. The highly charged and fluorescence-labeled nanoparticles non-specifically bind to the cell membranes, followed by cellular uptake through endocytosis. The nanoparticles form aggregates inside endosomes, which yields a punctuated staining pattern. Cellular internalization of the nanoparticles is dependent on the dosage and time. Uptake efficiency can be enhanced three-fold by application of an external magnetic field. The nanoparticles are low cytotoxicity and suitable for simultaneously noninvasive fluorescence and magnetic resonance imaging application.
authors.affiliation: Department of Pharmaceutics, China Pharmaceutical University, Nanjing, 210009, China.|Department of Polymer Science &Engineering and Key Laboratory of High Performance Polymer Materials &Technology of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry &Chemical Engineering, Nanjing University, Nanjing 210023, China.
authors.forename: Minjie
authors.initials: M
authors.lastname: Sun
authors.affiliation: Department of Polymer Science &Engineering and Key Laboratory of High Performance Polymer Materials &Technology of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry &Chemical Engineering, Nanjing University, Nanjing 210023, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Sun
authors.affiliation: Department of Polymer Science &Engineering and Key Laboratory of High Performance Polymer Materials &Technology of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry &Chemical Engineering, Nanjing University, Nanjing 210023, China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Polymer Science &Engineering and Key Laboratory of High Performance Polymer Materials &Technology of MOE, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry &Chemical Engineering, Nanjing University, Nanjing 210023, China.
authors.forename: Qun-Dong
authors.initials: QD
authors.lastname: Shen
authors.affiliation: Department of Pathology and Laboratory of Electron Microscopy, Jinling Hospital, Nanjing 210002, China.
authors.forename: Shaojun
authors.initials: S
authors.lastname: Jiang
mesh_terms: D016923:Cell Death; D045744:Cell Line, Tumor; D003116:Color; D003952:Diagnostic Imaging / Q000379:methods*; D004705:Endocytosis; D005456:Fluorescent Dyes / Q000737:chemistry; D006801:Humans; D058185:Magnetite Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D015335:Molecular Probes / Q000737:chemistry*; D009369:Neoplasms / Q000175:diagnosis*; D011108:Polymers / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D005456:Fluorescent Dyes; D058185:Magnetite Nanoparticles; D015335:Molecular Probes; D011108:Polymers