title: Mechanism of cellular uptake of highly fluorescent conjugated polymer nanoparticles.
abstract: Conjugated polymer nanoparticles are formed by precipitation of highly fluorescent conjugated polymers to form small nanoparticles with extremely bright fluorescence. We characterized cellular uptake and cytotoxicity of 18 ± 5 nm PFBT conjugated polymer nanoparticles in J774A.1 cells. Significant nanoparticle uptake was observed, indicating efficient nanoparticle entry into cells, even for short (1 h) incubations. The high fluorescence of these nanoparticles allows extremely low loading concentrations; PFBT nanoparticle fluorescence in cells could be detected with loading concentrations of 155 pM (270 ppb). Cellular uptake slows at low temperature, consistent with endocytic entry. Nanoparticles colocalize with Texas Red dextran and are trafficked to lysosomes, as demonstrated by the location of nanoparticle fluorescence in perinuclear organelles that also stain with an anti-LAMP-1 antibody. Inhibition of uptake by phosphoinositide 3-kinase inhibitors implicates macropinocytosis as the operative endocytic mechanism. No significant cytotoxic or inflammatory effects could be observed, making PFBT nanoparticles attractive probes for live cell imaging.
authors.affiliation: Department of Chemistry, Clemson University, Clemson, SC 29634, USA.
authors.forename: Lawrence P
authors.initials: LP
authors.lastname: Fernando
authors.forename: Prakash K
authors.initials: PK
authors.lastname: Kandel
authors.forename: Jiangbo
authors.initials: J
authors.lastname: Yu
authors.forename: Jason
authors.initials: J
authors.lastname: McNeill
authors.forename: P Christine
authors.initials: PC
authors.lastname: Ackroyd
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Christensen
mesh_terms: D000818:Animals; D018929:Cell Culture Techniques; D002460:Cell Line; D005434:Flow Cytometry; D005449:Fluorenes / Q000737:chemistry / Q000378:metabolism*; D005453:Fluorescence; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D018625:Microscopy, Atomic Force; D008856:Microscopy, Fluorescence; D057054:Molecular Imaging / Q000379:methods*; D053758:Nanoparticles / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry / Q000378:metabolism*
chemical_list: D005449:Fluorenes; D011108:Polymers; C556103:poly((9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-(2,1',3)-thiadiazole))