- Imaging the binding ability of proteins immobilized on surfaces with different orientations by using liquid crystals
-
We report an investigation of the binding ability of a protein immobilized on surfaces with different orientations but in identical interfacial microenvironments. The surfaces present mixed self-assembled monolayers (SAMs) of 11 -[19-carboxymethylhexa(ethylene glycol)]undecyl-1-thiol, 1, and 11-tetra(ethylene glycol) undecyl-1-thiol, 2. Whereas 2 is used to define an interfacial microenvironment that prevents nonspecific adsorption of proteins, 1 was activated by two different schemes to immobilize ribonuclease A (RNase A) in either a preferred orientation or random orientations. The binding of the ribonuclease inhibitor protein (RI) to RNase A on these surfaces was characterized by using ellipsometry and the orientational behavior of liquid crystals. Ellipsometric measurements indicate identical extents of immobilization of RNase A via the two schemes. Following incubation of both surfaces with RI, however, ellipsometric measurements indicate a 4-fold higher binding ability of the RNase A immobilized with a preferred orientation over RNase A immobilized with a random orientation. The higher binding ability of the oriented RNase A over the randomly oriented RNase A was also apparent in the orientational behavior of nematic liquid crystals of 4-cyano-4′- pentylcyanobiphenyl (5CB) overlayed on these surfaces. These results demonstrate that the orientations of proteins covalently immobilized in controlled interfacial microenvironments can influence the binding activities of the immobilized proteins. Results reported in this article also demonstrate that the orientational states of proteins immobilized at surfaces can be distinguished by examining the optical appearances of liquid crystals.
- Luk, Yan-Yeung,Tingey, Matthew L.,Dickson, Kimberly A.,Raines, Ronald T.,Abbott, Nicholas L.
-
-
Read Online
- Adsorption of proteins onto surfaces containing end-attached oligo(ethylene oxide): A model system using self-assembled monolayers
-
This paper reports a study of the adsorption of four proteins - fibrinogen, lysozyme, pyruvate kinase, and RNAse A - to self-assembled monolayers (SAMs) on gold. The SAMs examined were derived from thiols of the structure HS(CH2) 10R, where R was CH3, CH2OH, and oligo(ethylene oxide). Monolayers that contained a sufficiently large mole fraction of alkanethiolate groups terminated in oligo(ethylene oxide) chains resisted the kinetically irreversible, nonspecific adsorption of all four proteins. Longer chains of oligo(ethylene oxide) were resistant at lower mole fractions in the monolayer. Resistance to the adsorption of proteins increased with the length of the oligo(ethylene oxide) chain: the smallest mole fraction of chains that prevented adsorption was proportional to 1-0.4, where n represents the number of ethylene oxide units per chain. Termination of the oligo(ethylene oxide) chains with a methoxy group instead of a hydroxyl group had little or no effect on the amount of protein adsorbed. The amount of pyruvate kinase that adsorbed to mixed SAMs containing hexa(ethylene oxide)-terminated chains depended upon the temperature. When the mole fraction of oligo(ethylene oxide) groups in the monolayer was below the level needed to prevent adsorption, more pyruvate kinase adsorbed to the monolayer at 37 °C than at 25 °C. No difference was observed between adsorption at 25 and 4 °C.
- Prime, Kevin L.,Whitesides, George M.
-
-
Read Online
- Facile method for development of ligand-patterned substrates induced by a chemical reaction
-
Choose a pattern: A simple and efficient method for ligand patterning on a surface is reported. An organic chemical reaction induces various patterns of an amine functional group, which is further conjugated to a cell adhesion ligand to result in cell patterning (see figure). Copyright
- Seo, Hyunjung,Choi, Inseong,Lee, Jeongwook,Kim, Sohyun,Kim, Dong-Eun,Kim, Sang Kyung,Yeo, Woon-Seok
-
supporting information; experimental part
p. 5804 - 5807
(2011/06/27)
-
- Synthesis of benzaldehyde-functionalized glycans: A novel approach towards glyco-SAMs as a tool for surface plasmon resonance studies
-
In recent years the interest in tools for investigating carbohydrateprotein (CPI) and carbohydrate-carbohydrate interactions (CCI) has increased significantly. For the investigation of CPI and CCI, several techniques employing different linking methods are available. Surface plasmon resonance (SPR) imaging is a most appropriate tool for analyzing the formation of self-assembled monolayers (SAM) of carbohydrate derivatives, which can mimic the glycocalyx. In contrast to the SPR imaging methods used previously to analyze CPI and CCI, the novel approach reported herein allows a facile and rapid synthesis of linker spacers and carbohydrate derivatives and enhances the binding event by controlling the amount and orientation of ligand. For immobilization on biorepulsive amino-functionalized SPR chips by reductive amination, diverse aldehyde-functionalized glycan structures (glucose, galactose, mannose, glucosamine, cellobiose, lactose, and lactosamine) have been synthesized in several facile steps that include olefin metathesis. Effective immobilization and the first binding studies are presented for the lectin concanavalin A.
- Kopitzki, Sebastian,Jensen, Knud J.,Thiem, Joachim
-
experimental part
p. 7017 - 7029
(2010/09/10)
-
- A new glycosylation method. Part 2: Study of carbohydrate elongation onto the gold nanoparticles in a colloidal phase
-
A new reaction for carbohydrate elongation for synthesis of oligosaccharide using gold colloidal nanoparticles (GCNPs) has been developed. The gold core in this colloidal phase synthesis was prepared by a reduction of tetrachloroauric acid with 30,31-dithia-3,6,9,12,15,18,43,46,49,52,55,58-dodecaoxa-1,60-hexacontanediol. The presented alkanethionyl oligomeric ethylene glycol worked as a stabilizer of GCNPs and as a linker in chemical elongations of carbohydrates. This colloidal phase synthesis has several advantages such as (1) remnants of reagents and glycosyl donors in each reaction could be easily removed by ultrafiltration or gel filtration column chromatography, (2) further purifications are not required, and (3) the reactions can be monitored by MALDI-TOF MS directly without any pretreatment. In fact, we have successfully synthesized lactose derivative on GCNPs and will report these results in this paper.
- Shimizu, Hiroki,Sakamoto, Masahiro,Nagahori, Noriko,Nishimura, Shin-Ichiro
-
p. 2418 - 2425
(2007/10/03)
-
- Gold glyconanoparticles: Synthetic polyvalent ligands mimicking glycocalyx-like surfaces as tools for glycobiological studies
-
A simple and versatile methodology is described for tailoring sugar-functionalised gold nanoclusters (glyconanoparticles) that have 3D polyvalent carbohydrate display and globular shapes. This methodology allows the preparation of glyconanoparticles with biologically significant oligosaccharides as well as with differing carbohydrate density. Fluorescent glyconanoparticles have been also prepared for labelling cells in biological tests. The materials are water soluble, stable under physiological conditions and present an exceptional small core size. All of them have been characterised by 1H NMR, UV and IR spectroscopy, TEM and elemental analysis. Their highly polyvalent network can mimic glycosphingolipid clustering and interactions at the plasma membrane, providing an controlled system for glycobiological studies. Furthermore, they are useful building blocks for the design of nanomaterials.
- Barrientos, Africa G.,De la Fuente, Jesus M.,Rojas, Teresa C.,Fernandez, Asuncion,Penades, Soledad
-
p. 1909 - 1921
(2007/10/03)
-
- Factors that determine the protein resistance of oligoether self-assembled monolayers - Internal hydrophilicity, terminal hydrophilicity, and lateral packing density
-
Protein resistance of oligoether self-assembled monolayers (SAMs) on gold and silver surfaces has been investigated systematically to elucidate structural factors that determine whether a SAM will be able to resist protein adsorption. Oligo(ethylene glycol) (OEG)-, oligo(propylene glycol)-, and oligo(trimethylene glycol)-terminated alkanethiols with different chain lengths and alkyl termination were synthesized as monolayer constituents. The packing density and chemical composition of the SAMs were examined by XPS spectroscopy; the terminal hydrophilicity was characterized by contact angle measurements. IRRAS spectroscopy gave information about the chain conformation of specific monolayers; the amount of adsorbed protein as compared to alkanethiol monolayers was determined by ellipsometry. We found several factors that in combination or by themselves suppress the protein resistance of oligoether monolayers. Monolayers with a hydrophobic interior, such as those containing oligo(propylene glycol), show no protein resistance. The lateral compression of oligo(ethylene glycol) monolayers on silver generates more highly ordered monolayers and may cause decreased protein resistance, but does not necessarily lead to an all-trans chain conformation of the OEG moieties. Water contact angles higher than 70° on gold or 65° on silver reduce full protein resistance. We conclude that both internal and terminal hydrophilicity favor the protein resistance of an oligoether monolayer. It is suggested that the penetration of water molecules in the interior of the SAM is a necessary prerequisite for protein resistance. We discuss and summarize the various factors which are critical for the functionality of "inert" organic films.
- Herrwerth, Sascha,Eck, Wolfgang,Reinhardt, Sven,Grunze, Michael
-
p. 9359 - 9366
(2007/10/03)
-
- Formation of self-assembled monolayers by chemisorption of derivatives of oligo(ethylene glycol) of structure HS(CH2)11(OCH2CH2)mOH on gold
-
This paper describes the preparation of oligo(ethylene glycol)-terminated alkanethiols having structure HS-(CH2)11(OCH2CH2)mOH (m = 3-7) and their use in the formation of self-assembled monolayers (SAMs) on gold. A combination of experimental evidence derived from X-ray photoelectron spectroscopy (XPS), measurement of contact angles, and ellipsometry implies substantial disorder in the oligo(ethylene glycol)-containing segment. The order in the -(CH2)11- group is not denned by the available evidence. The SAMs are moderately hydrophilic: θa(H2O) = 34-38°; θr(H2O) = 22-25°. A study of monolayers containing mixtures of HS(CH2)11CH3 and HS(CH2)11(OCH2CH2)6OH suggests that the oligo(ethylene glycol) moieties are effective at preventing underlying methylene groups from influencing wetting by water. A limited study demonstrates that these oligo(ethylene glycol)-containing SAMs resist the adsorption of protein from solution and suggests that SAMs will be a useful model system for studying the adsorption of proteins onto organic surfaces.
- Pale-Grosdemange, Catherine,Simon, Ethan S.,Prime, Kevin L.,Whitesides, George M.
-
-