title: Liposome encapsulation of thiol-capped CdTe quantum dots for enhancing the intracellular delivery.
abstract: Although water soluble thiol-capped quantum dots (QDs) have been widely used as photoluminescence (PL) probes in various applications, the negative charges on thiol terminals limit the cell uptake hindering their applications in cell imaging. The commercial liposome complex (Sofast®) was used to encapsulate these QDs forming the liposome vesicles with the loading efficiency as high as about 95%. The cell uptakes of unencapsulated QDs and QD loaded liposome vesicles were comparatively studied by a laser scanning confocal microscope. We found that QD loaded liposome vesicles can effectively enhance the intracellular delivery of QDs in three cell lines (human osteosarcoma cell line (U2OS); human cervical carcinoma cell line (Hela); human embryonic kidney cell line (293 T)). The photobleaching of encapsulated QDs in cells was also reduced comparing with that of unencapsulated QDs, measured by the PL decay of cellular QDs with a continuous laser irradiation in the microscope. The flow cytometric measurements further showed that the enhancing ratios of encapsulated QDs on cell uptake are about 4-8 times in 293 T and Hela cells. These results suggest that the cationic liposome encapsulation is an effective modality to enhance the intracellular delivery of thiol-capped QDs.
authors.affiliation: State Key Laboratory of Surface Physics and Department of Physics, Fudan University, 220 Handan Road, Shanghai 200433, People's Republic of China.
authors.forename: Jun-Yong
authors.initials: JY
authors.lastname: Wang
authors.forename: Jin-Feng
authors.initials: JF
authors.lastname: Zhao
authors.forename: Pei-Nan
authors.initials: PN
authors.lastname: Wang
authors.forename: Wu-Li
authors.initials: WL
authors.lastname: Yang
authors.forename: Ji-Yao
authors.initials: JY
authors.lastname: Chen
mesh_terms: D019187:Cadmium Compounds / Q000737:chemistry / Q000493:pharmacokinetics*; D002478:Cells, Cultured; D005456:Fluorescent Dyes / Q000737:chemistry / Q000493:pharmacokinetics*; D006367:HeLa Cells; D006801:Humans; D008081:Liposomes / Q000737:chemistry*; D045663:Quantum Dots; D013438:Sulfhydryl Compounds / Q000737:chemistry*; D013691:Tellurium / Q000737:chemistry / Q000493:pharmacokinetics*; D014018:Tissue Distribution
chemical_list: D019187:Cadmium Compounds; D005456:Fluorescent Dyes; D008081:Liposomes; D013438:Sulfhydryl Compounds; D013691:Tellurium; C028337:cadmium telluride