title: Alkyl passivation and amphiphilic polymer coating of silicon nanocrystals for diagnostic imaging.
abstract: A method to produce biocompatible polymer-coated silicon nanocrystals for medical imaging is shown. Silica-embedded Si nanocrystals are formed by HSQ thermolysis. The nanocrystals are then liberated from the oxide and terminated with Si-H bonds by HF etching, followed by alkyl monolayer passivation by thermal hydrosilylation. The Si nanocrystals have an average diameter of 2.1 nm ± 0.6 nm and photoluminesce with a peak emission wavelength of 650 nm, which lies within the transmission window of 650-900 nm that is useful for biological imaging. The hydrophobic Si nanocrystals are then coated with an amphiphilic polymer for dispersion in aqueous media with the pH ranging between 7 and 10 and an ionic strength between 30 mM and 2 M, while maintaining a bright and stable photoluminescence and a hydrodynamic radius of only 20 nm. Fluorescence imaging of polymer-coated Si nanocrystals in biological tissue is demonstrated, showing the potential for in vivo imaging.
authors.affiliation: Department of Chemical Engineering, The University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Colin M
authors.initials: CM
authors.lastname: Hessel
authors.forename: Michael R
authors.initials: MR
authors.lastname: Rasch
authors.forename: Jose L
authors.initials: JL
authors.lastname: Hueso
authors.forename: Brian W
authors.initials: BW
authors.lastname: Goodfellow
authors.forename: Vahid A
authors.initials: VA
authors.lastname: Akhavan
authors.forename: Priyaveena
authors.initials: P
authors.lastname: Puvanakrishnan
authors.forename: James W
authors.initials: JW
authors.lastname: Tunnel
authors.forename: Brian A
authors.initials: BA
authors.lastname: Korgel
mesh_terms: D000477:Alkylating Agents / Q000737:chemistry / Q000494:pharmacology; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis* / Q000737:chemistry; D003952:Diagnostic Imaging / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions / Q000187:drug effects; D006900:Hydroxylation / Q000187:drug effects / Q000502:physiology; D008954:Models, Biological; D053758:Nanoparticles / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods; D011108:Polymers / Q000737:chemistry* / Q000494:pharmacology; D012825:Silicon / Q000737:chemistry*; D013499:Surface Properties; D013501:Surface-Active Agents / Q000737:chemistry* / Q000494:pharmacology; D014961:X-Ray Diffraction
chemical_list: D000477:Alkylating Agents; D020099:Coated Materials, Biocompatible; D011108:Polymers; D013501:Surface-Active Agents; D012825:Silicon
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