title: Amphiphilic hyperbranched fluoropolymers as nanoscopic 19F magnetic resonance imaging agent assemblies.
abstract: Three hyperbranched fluoropolymers were synthesized and their micelles were constructed as potential (19)F MRI agents. A hyperbranched star-like core was first synthesized via atom transfer radical self-condensing vinyl (co)polymerization (ATR-SCVCP) of 4-chloromethyl styrene (CMS), lauryl acrylate (LA), and 1,1,1-tris(4'-(2''-bromoisobutyryloxy)phenyl)ethane (TBBPE). The polymerization gave a small core with M n of 5.5 kDa with PDI of 1.6, which served as a macroinitiator. Trifluoroethyl methacrylate (TFEMA) and tert-butyl acrylate (tBA) in different ratios were then "grafted" from the core to give three polymers with M(n) of about 120 kDa and PDI values of about 1.6-1.8. After acidolysis of the tert-butyl ester groups, amphiphilic, hyperbranched star-like polymers with M(n) of about 100 kDa were obtained. These structures were subjected to micelle formation in aqueous solution to give micelles having TEM-measured diameters ranging from 3-8 nm and DLS-measured hydrodynamic diameters from 20-30 nm. These micelles gave a narrow, single resonance by (19)F NMR spectroscopy, with a half-width of approximately 130 Hz. The T1/T2 parameters were about 500 and 50 ms, respectively, and were not significantly affected by the composition and sizes of the micelles. (19)F MRI phantom images of these fluorinated micelles were acquired, which demonstrated that these fluorinated micelles maybe useful as novel (19)F MRI agents for a variety of biomedical studies.
authors.affiliation: Department of Chemistry, Washington University in Saint Louis, Saint Louis, Missouri 63130, USA.
authors.forename: Wenjun
authors.initials: W
authors.lastname: Du
authors.forename: Andreas M
authors.initials: AM
authors.lastname: Nyström
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.forename: Kenya T
authors.initials: KT
authors.lastname: Powell
authors.forename: Yali
authors.initials: Y
authors.lastname: Li
authors.forename: Chong
authors.initials: C
authors.lastname: Cheng
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Wickline
authors.forename: Karen L
authors.initials: KL
authors.lastname: Wooley
mesh_terms: D000085:Acetates / Q000737:chemistry; D002152:Calorimetry, Differential Scanning / Q000379:methods; D003287:Contrast Media / Q000494:pharmacology; D005462:Fluorine Radioisotopes / Q000737:chemistry*; D007850:Lauric Acids / Q000737:chemistry; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy; D008689:Methacrylates / Q000737:chemistry; D008823:Micelles; D018625:Microscopy, Atomic Force / Q000379:methods; D046529:Microscopy, Electron, Transmission; D008970:Molecular Weight; D054813:Polyhydroxyalkanoates / Q000737:chemistry; D011108:Polymers / Q000737:chemistry*; D011137:Polystyrenes / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000085:Acetates; D003287:Contrast Media; D005462:Fluorine Radioisotopes; D007850:Lauric Acids; D008689:Methacrylates; D008823:Micelles; D054813:Polyhydroxyalkanoates; D011108:Polymers; D011137:Polystyrenes; C421257:poly(lauryl methacrylate); C426943:poly(p-chloromethylstyrene); C089834:tert-butyl acetate
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