- One-phase synthesis of water-soluble gold nanoparticles with control over size and surface functionalities
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We report a simple and efficient synthetic method to prepare gold nanoparticles (AuNPs) in aqueous phase using HAuCl4 and poly(ethylene glycol) (PEG) ligands appended with bidentate anchoring groups. Our approach provides narrow size distribution nanocrystals over the size range between 1.5 and 18 nm; this range is much wider than those achieved using other small molecules and polymer ligands. The NP size was simply controlled by varying the molar ratio of Au-to-PEG ligand precursors. Further passivation of the as-prepared AuNPs permitted in situ functionalization of the NP surface with the desired functional groups. The prepared AuNPs exhibit remarkable stability in the presence of high salt concentrations, over a wide range of pHs (2-13), and a strong resistance to competition from dithiothreitol (DTT). These results are a clear manifestation of the advantages offered by our synthetic approach to prepare biocompatible AuNPs, where modular, multifunctional ligands presenting strong anchoring groups and hydrophilic PEG chains are used.
- Oh, Eunkeu,Susumu, Kimihiro,Goswami, Ramasis,Mattoussi, Hedi
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Read Online
- Covalent capture and electrochemical quantification of pathogenicE. coli
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PathogenicE. colipose a significant threat to public health, as strains of this species cause both foodborne illnesses and urinary tract infections. Using a rapid bioconjugation reaction, we selectively captureE. coliat a disposable gold electrode from complex solutions and accurately quantify the pathogenic microbes using electrochemical impedance spectroscopy.
- Klass, Sarah H.,Sofen, Laura E.,Hallberg, Zachary F.,Fiala, Tahoe A.,Ramsey, Alexandra V.,Dolan, Nicholas S.,Francis, Matthew B.,Furst, Ariel L.
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supporting information
p. 2507 - 2510
(2021/03/16)
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- PRODRUGS OF PEPTIDE EPOXY KETONE PROTEASE INHIBITORS
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This disclosure features compounds that are useful as pro-drugs of epoxy ketone protease inhibitors.
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Page/Page column 213
(2014/02/15)
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- Multivalent interaction and selectivities in selectin binding of functionalized gold colloids decorated with carbohydrate mimetics
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Colloidal gold particles with functionalized organic shells were applied as novel selectin binders. The ligand shell was terminated with different monocyclic carbohydrate mimetics as simplified analogs of the sLex unit found in biological selectin ligands. The multivalent presentation of the sulfated selectin binding epitopes on the gold particles led to extremely high binding affinities towards L- and P-selectin and IC50 values in the subnanomolar range. Depending on the ring size of the sulfated carbohydrate mimetic, its substitution pattern and its configuration, different selectivities for either L-selectin or P-selectin were obtained. These selectivities were not found for gold particles with simple acyclic sulfated alcohols, diols and triols in the ligand shell. In addition, the influence of the particle size and the thickness of the hydrophobic organic shell were systematically investigated.
- Roskamp, Meike,Enders, Sven,Pfrengle, Fabian,Yekta, Shahla,Dekaris, Vjekoslav,Dernedde, Jens,Reissig, Hans-Ulrich,Schlecht, Sabine
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supporting information; experimental part
p. 7448 - 7456
(2011/12/03)
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- Conformation of receptor adopted upon interaction with virus revealed bysite-specific fluorescence quenchers and FRET analysis
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Human rhinovirus serotype 2 (HRV2) specifically binds to very-low-density lipoprotein receptor (VLDLR). Among the eight extracellular repeats ofVLDLR, the third module (V3) has the highest affinity for the virus, an d 12 copies of the genetically engineered concatamer V33333-His6 were found to bind per virus particle. In the present study, ring formation of V33333-His 6 about each of the 12 5-fold symmetry axes on HRV2 was demonstrated by fluorescence resonance energy transfer (FRET) between donor and acceptor on N- and C-terminus, respectively. Inparticular, the N-terminus of V33333-His6 was labeled with f luorescein, and the C-terminus with a new quencher which was bound to the His6 tag with nanomolar affinity (Kd ～10-8 M) in the presence of 2 μM NiCl 2.
- Wruss, Juergen,Pollheimer, Philipp D.,Meindl, Irene,Reichel, Annett,Schulze, Katrin,et al.
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supporting information; experimental part
p. 5478 - 5482
(2009/09/25)
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- Synthesis of a series of oligo(ethylene glycol)-terminated alkanethiol amides designed to address structure and stability of biosensing interfaces
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A strategy for the synthesis of a series of closely related oligo(ethylene glycol)-terminated alkanethiol amides (principally HS(CH2)mCONH(CH2CH2O) nH; m = 2, 5, 11, 15, n = 1, 2, 4, 6, 8, 10, 12) and analogous esters has been developed. These compounds were made to study the structure and stability of self-assembled monolayers (SAMs) on gold in the prospect of designing new biosensing interfaces. For this purpose, monodisperse heterofunctional oligo(ethylene glycols) with up to 12 units were prepared. Selective monoacylation of the symmetrical tetra- and hexa(ethylene glycol) diols as their mesylates with the use of silver(I) oxide was performed. The synthetic approach was based on carbodiimide couplings of various oligo(ethylene glycol) derivatives to ω-(acetylthio) carboxylic acids via a terminal amino or hydroxyl function. SAM structures on gold were studied with respect to thickness, wettability (water contact angles ～30°), and conformation. A good fit was obtained for the relation between monolayer thickness (d) and the number of units in the oligo(ethylene glycol) chain (n): d = 2.8n + 21.8 (A). Interestingly, the corresponding infrared spectroscopy analysis showed a dramatic change in conformation of the oligomeric chains from all-trans (n = 4) to helical (n ≥ 6) conformation. A crystalline helical structure was observed in the SAMs for n > 6.
- Svedhem,Hollander,Shi,Konradsson,Liedberg,Svensson
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p. 4494 - 4503
(2007/10/03)
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- Kinetics of Intramolecular Alkyl Radical Attack on Sulfur in Disulfides and Thioesters
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The 4-(alkyldithio)butyl radicals 8a and c, and the 4-(phenyldithio)butyl radical 8b, generated from the corresponding esters of N-hydroxypyridine-2(1H)-thione, undergo fast exo-cyclisation by SHi attack at sulfur.Similarly, the 5-(alkyldithio)pentyl radical 8d undergoes 1,6-ring formation.The rate constants for cyclisation were determined by photolysis of the radical precursors in the presence of appropriate thiols.Butyl and pentyl radicals bearing ω-acetylthio or ω-benzoylthio substituents also undergo ring closure but much more slowly.The kinetics of these intramolecular SH2 reactions are discussed and compared with those for the intermolecular attack of hexyl radicals on diphenyl disulfide and on dibutyl disulfide.
- Beckwith, Athelstan L. J.,Duggan, Sandhya A. M.
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p. 1509 - 1518
(2007/10/02)
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- "Mercaptan-Tail" Porphyrins: Synthetic Analogues for the Active Site of Cytochrome P-450
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The synthesis and characterization of a series of tetraarylporphyrins which bear covalently attached alkyl and aryl mercaptans designed to serve as axial ligands are described.The coordination chemistry of the iron(II) complexes of these "mercaptan-tail" porphyrins has been investigated by 1H NMR, IR, and electronic absorption spectroscopy, magnetic circular dichroism, and magnetic susceptibility measurements.Ferrous complexes of the alkyl mercaptan-tail porphyrins appear to remain four-coordinate, intermediate spin (S = 1) in solution.The situation is less clear in the case of appended aryl mercaptans and a "tail-on/tail-off" equilibrium is implicated.In the presence of carbon monoxide, however, binding of thiol trans to CO is observed in both the alkyl and aryl cases.By the addition of an appropriate base, six-coordinate mercaptide-Fe(II)-CO complexes can be generated; these reproduce quite well the characteristic absorption and MCD spectra of cytochrome P-450, suggesting that such compounds are indeed viable models for the active site of cytochrome P-450.
- Collman, James P.,Groh, Susan E.
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p. 1391 - 1403
(2007/10/02)
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