Synthesis and characterization of oligonucleotide conjugates bearing electroactive labels.

Oxime bond formation has been applied to the preparation of oligonucleotides labeled with electrochemical ferrocene and viologen labels. Aminooxy functionalized ferrocene and viologen derivatives were prepared by a straightforward route and efficiently conjugated with aldehyde containing oligonucleotides either at 3' or 5' end. Both labels were found to not disturb the recognition properties of the oligonucleotide. The versatility of the method was further demonstrated by preparing bi-functionalized conjugates with a disulfide at 3' end and an electrochemical label at 5' end.

Direct characterization of native chemical ligation of peptides on silicon nanowires.

We describe the site-specific and chemoselective immobilization of peptides on hydrogen-terminated silicon nanowires (SiNWs) using native chemical ligation (NCL) (i.e., the reaction of a thioester group with a cysteine moiety to give a stable amide bond). The SiNWs investigated in this work were grown via a vapor-liquid-solid mechanism and functionalized with a thioester moiety. The immobilization of the peptides on the SiNWs was demonstrated by synthesizing peptides with an N-terminal cysteine residue and labeled with tetramethylrhodamine or trifluoromethyl groups that were detected by fluorescence and X-ray photoelectron spectroscopy, respectively. The peptides labeled with tetramethylrhodamine or trifluoromethyl groups for fluorescence or X-ray photoelectron spectroscopy (XPS) detection studies were synthesized with an N-terminal cysteine residue. N-Terminal seryl peptides and carboxy-terminated SiNWs were used as controls to demonstrate the chemoselectivity of the peptide immobilization.

Towards the simplification of protein synthesis: iterative solid-supported ligations with concomitant purifications.

Please release me: a new linker for the temporary tagging of peptides at their N-terminus after solid-phase elongation, and its potential for capture/release purification is demonstrated. This concept is extended to a remarkably efficient self-purifying N-to-C iterative triazole ligation strategy, which is applied to the synthesis of a polypeptide having 160 residues, in a high purity without the need for chromatographic purification (orange blocks: peptide segments).

Surface patterning of (bio)molecules onto the inner wall of fused-silica capillary tubes.

An efficient photochemical method for the site-specific immobilization and patterning of (bio)molecules inside glass capillary tubes is reported. The strategy involves the photodeprotection of reactive aminooxy groups on surfaces and subsequent reaction with aldehyde containing (bio)molecules.

Use of gamma-aminopropyl-coated glass surface for the patterning of oligonucleotides through oxime bond formation.

The present work reports on the preparation of glass surfaces coated with NPPOC-protected aminooxy groups and their use for the patterning of oligonucleotides on glass slides and in capillary tubes. The method involves the use of surfaces coated with amino groups using (gamma-aminopropyl)triethoxy silane and subsequent grafting of the aminooxy groups by using the activated ester 1. The NPPOC-protected aminooxy groups on the surfaces can be cleaved upon irradiation. The free aminooxy groups so obtained are subsequently reacted with aldehyde-containing oligonucleotides to achieve efficient surface patterning.

Carbohydrate microarrays in 96-well polystyrene microtiter plates.

A method for the preparation of carbohydrate microarrays inside 96-well polystyrene microtiter plates is described. The key step in this strategy represents the synthesis of carbohydrate-dextran conjugates by copper (I)-catalyzed [3 + 2] cycloaddition between alkyne carbohydrate derivative and a specially designed azido dextran polymer. The conjugates adsorb efficiently on polystyrene surface and can be printed inside 96-well plates using a non-contact piezoelectric microarrayer. Model interactions with a selection of lectins (concanavalin A, wheat germ agglutinin, Erythrina Cristagalli) display the efficiency of the immobilization method, its reproducibility and the specificity of biomolecular interactions occurring at the polystyrene-water interface.

Polysaccharide microarrays: application to the identification of heparan sulphate mimetics.

The interaction of polysaccharides with proteins modulates or triggers many biological effects. In particular, heparan sulphate proteoglycans (HSPGs) have multiple regulatory interactions with growth factors, enzymes, enzyme inhibitors, and some components of the extracellular matrix. The important role played by HSPGs has motivated the synthesis and selection of HSPG mimetics for modulating the biological activity of HS-binding proteins. We present hereinafter an efficient polysaccharide microarray method that allows the screening of HS-mimetic libraries towards HS-binding growth factors, a major class of polypeptides whose inhibition or potentiation is of high medical interest.

Three-component synthesis of neoglycopeptides using a Cu(II)-triggered aminolysis of peptide hydrazide resin and an azide-alkyne cycloaddition sequence.

Copper(II)-induced oxidative aminolysis of hydrazides generates Cu(I), the catalyst of the azide-alkyne cycloaddition. This feature was exploited to design a novel solid phase detaching three-component reaction permitting the conversion of supported peptide hydrazides into 1,2,3-triazole linked C-terminal neoglycopeptides.

Efficient surface patterning of oligonucleotides inside a glass capillary through oxime bond formation.

The efficient surface patterning of oligonucleotides was accomplished onto the inner wall of fused-silica capillary tubes as well as on the surface of glass slides through oxime bond formation. The robustness of the method was demonstrated by achieving the surface immobilization of up to three different oligonucleotide sequences inside the same capillary tube. The method involves the preparation of surfaces grafted with reactive aminooxy functionalities masked with the photocleavable protecting group, 2-(2-nitrophenyl) propyloxycarbonyl group (NPPOC). Briefly, NPPOC-aminooxy silane 1 was prepared and used to silanize the glass surfaces. The NPPOC group was cleaved under brief irradiation to unmask the reactive aminooxy group on surfaces. These reactive aminooxy groups were allowed to react with aldehyde-containing oligonucleotides to achieve an efficient surface immobilization. The advantage associated with the present approach is that it combines the high-coupling efficiency of oxime bond formation with the convenience associated with the use of photolabile groups. The present strategy thus offers an alternative approach for the immobilization of biomolecules in the microchannels of "labs on a chip" devices.