title: Ligand-installed PEGylated bionanosphere.
abstract: The synthesis of poly(ethylene glycol)-b-poly(2-N,N-dimethylaminoethylmethacrylate) processing an acetal group at the PEG chain end (acetal-PEGPAMA) is reported. The obtained acetal-PEGPAMA block copolymer was found to reduce tetrachloroauric acid at room temperature to produce gold nanoparticles. The size of these nanoparticles was controllable in the range of 6 to 13 nm by changing the initial Au3+: polymer ratio. In addition to the reduction of tetrachloroauric acid, acetal-PEGPAMA bonds on the surface of the obtained gold nanoparticles to improve their dispersion stability in an aqueous medium even at a salt concentration as high as two. Biotinyl-PEGPAMA-anchored gold nanoparticles undergo specific aggregation in the presence of streptavidin thereby revealing their promising utility as colloidal sensing systems for use in biological systems. Biotin-PEGPAMA can also be utilised for the preparation of a functionally PEGylated quantum dot (QD). When CdCl2 and Na2S were mixed in aqueous media in the presence of the biotin-PEGPAMA, a CdS QD with an approximately 5 nm size was prepared. The polyamine segment was anchored onto the surface of the formed CdS nanoparticle, whereas the PEG segment was tethered onto the surface to form a hydrophilic palisade, thus improving the dispersion stability in aqueous media even under a high salt concentration condition. An effective fluorescent resonance energy transfer (FRET) was observed by the specific interaction of the biotin-PEGPAMA stabilised CdS QD with TexasRed-labelled streptavidin with the physiological ionic strength of 0.15 M. The extent of the energy transfer was in proportion to the concentration of the TexasRed-streptavidin. This FRET system using the PEGylated CdS QD coupled with fluorescent-labelled protein can be utilised as a highly sensitive bioanalytical system.
authors.affiliation: Department of Materials Science, Tokyo University of Science, Noda 278-8510, Japan. nagasaki@nagalabo.jp
authors.forename: Y
authors.initials: Y
authors.lastname: Nagasaki
authors.forename: K
authors.initials: K
authors.lastname: Kataoka
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D001710:Biotin / Q000032:analysis* / Q000737:chemistry / Q000276:immunology; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D004337:Drug Carriers / Q000032:analysis / Q000737:chemistry; D031541:Fluorescence Resonance Energy Transfer / Q000295:instrumentation / Q000379:methods*; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods; D008024:Ligands; D008422:Materials Testing; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods; D043942:Nanotubes / Q000032:analysis / Q000737:chemistry*; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry*; D019809:Streptavidin / Q000032:analysis* / Q000737:chemistry / Q000276:immunology
chemical_list: D020099:Coated Materials, Biocompatible; D004337:Drug Carriers; D008024:Ligands; D011092:Polyethylene Glycols; D001710:Biotin; D019809:Streptavidin