title: Synthesis of poly(ethylene glycol)-graft-chitosan and using as ligand for fabrication of water-soluble quantum dots.
abstract: The synthesis of water-soluble, stable and biocompatible quantum dots (QDs) is of crucial importance for nanobiotechnology. A chitosan derivative, poly(ethylene glycol)-graft-chitosan (PEG-g-CS), was successfully synthesized and employed as ligand for the growth of CdSe QDs in aqueous solution. The bivalent Cd(2+) ions can coordinate with multiple amino-groups, thus they act as both inter- and intramolecular cross-linking agents. When the concentration of Cd(2+) was 0.2 mmol/L, the CdSe/PEG-g-CS aggregates formed an irregular cross-linked network; when the concentration was 1 mmol/L, a phenomenon of micro-phase separation emerged as a result of enrichment of CS phase; when the concentration was 2 mmol/L, spherical nanohybrids with the size of 30-50 nm were obtained. Moreover, a possible mechanism was proposed for the formation of CdSe/PEG-g-CS aggregates. Meantime, in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity tests against HepG2 cells were carried out, the corresponding results suggested that the CdSe QDs prepared using PEG-g-CS as ligand displayed very low cytotoxicity. Therefore, these water-soluble QD-polymer hybrids are expected to find promising applications in medical field.
authors.affiliation: School of Chemical Department, Key Laboratory of Soft Chemistry and Functional Materials of Ministry Education, Nanjing University of Science and Technology, Nanjing 210094, China.
authors.forename: Zhenchao
authors.initials: Z
authors.lastname: Jiang
authors.affiliation: School of Chemical Department, Key Laboratory of Soft Chemistry and Functional Materials of Ministry Education, Nanjing University of Science and Technology, Nanjing 210094, China.
authors.forename: Chunbao
authors.initials: C
authors.lastname: Zhao
authors.affiliation: School of Chemical Department, Key Laboratory of Soft Chemistry and Functional Materials of Ministry Education, Nanjing University of Science and Technology, Nanjing 210094, China. Electronic address: xhliu@mail.njust.edu.cn.
authors.forename: Xiaoheng
authors.initials: X
authors.lastname: Liu
mesh_terms: D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D048271:Chitosan / Q000138:chemical synthesis* / Q000737:chemistry / Q000633:toxicity; D056945:Hep G2 Cells; D006801:Humans; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D046529:Microscopy, Electron, Transmission; D011092:Polyethylene Glycols / Q000138:chemical synthesis* / Q000737:chemistry / Q000633:toxicity; D045663:Quantum Dots / Q000737:chemistry* / Q000633:toxicity; D012995:Solubility; D013050:Spectrometry, Fluorescence; D017550:Spectroscopy, Fourier Transform Infrared; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D008024:Ligands; D008823:Micelles; D014867:Water; D011092:Polyethylene Glycols; D048271:Chitosan
keywords: Chitosan; Graft copolymer; Hybrid aggregates; Poly(ethylene glycol); Water-soluble quantum dots