Surface Immobilization (surface + immobilization)

Distribution by Scientific Domains

Selected Abstracts

Protein Biochips: Oriented Surface Immobilization of Proteins,

Po-Chiao Lin
Abstract Substantial progress in biochip technologies has established an efficient and reliable platform for advanced biological and biomedical applications. In particular, the use of protein biochips in high-throughput screens provides high content information. We briefly introduce here recent developments in protein biochip preparation with a special focus on our own work on new methods for protein immobilization and protein microarray fabrication, including the application of the Diels-Alder reaction, Staudinger ligation, ,click' sulfonamide formation, and the photochemical thiol-ene reaction. These chemical methods allow for oriented, site-specific protein conjugation on solid surfaces with high sensitivity and specificity under mild, aqueous conditions. [source]

Carbon-Nanotube Based Electrochemical Biosensors: A Review

Joseph Wang
Abstract This review addresses recent advances in carbon-nanotubes (CNT) based electrochemical biosensors. The unique chemical and physical properties of CNT have paved the way to new and improved sensing devices, in general, and electrochemical biosensors, in particular. CNT-based electrochemical transducers offer substantial improvements in the performance of amperometric enzyme electrodes, immunosensors and nucleic-acid sensing devices. The greatly enhanced electrochemical reactivity of hydrogen peroxide and NADH at CNT-modified electrodes makes these nanomaterials extremely attractive for numerous oxidase- and dehydrogenase-based amperometric biosensors. Aligned CNT "forests" can act as molecular wires to allow efficient electron transfer between the underlying electrode and the redox centers of enzymes. Bioaffinity devices utilizing enzyme tags can greatly benefit from the enhanced response of the biocatalytic-reaction product at the CNT transducer and from CNT amplification platforms carrying multiple tags. Common designs of CNT-based biosensors are discussed, along with practical examples of such devices. The successful realization of CNT-based biosensors requires proper control of their chemical and physical properties, as well as their functionalization and surface immobilization. [source]

Fabrication of poly(ethylene glycol)-based hydrogels entrapping enzyme-immobilized silica nanoparticles

Eunji Jang
Abstract In this study, we immobilized enzymes by combining covalent surface immobilization and hydrogel entrapment. A model enzyme, glucose oxidase (GOX), was first covalently immobilized on the surface of silica nanoparticles (SNPs) via 3-aminopropyltriethoxysilane (APTES), and the resultant SNP-immobilized enzyme was physically entrapped within photopolymerized hydrogels prepared from two different molecular weights (MWs) (575 and 8000,Da) of poly(ethylene glycol)(PEG). The hydrogel entrapment resulted in a decrease in reaction rate and an increase in apparent Km of SNP-immobilized GOX, but these negative effects could be minimized by using hydrogel with a higher MW PEG, which provides higher water content and larger mesh size. The catalytic rate of the PEG 8000 hydrogel was about ten times faster than that of the PEG 575 hydrogel because of enhanced mass transfer. Long-term stability test demonstrated that SNP-immobilized GOX entrapped within hydrogel maintained more than 60% of its initial activity after a week, whereas non-entrapped SNP-immobilized GOX and entrapped GOX without SNP immobilization maintained less than 20% of their initial activity. Incorporation of SNPs into hydrogel enhanced the mechanical strength of the hydrogel six-fold relative to bare hydrogels. Finally, a hydrogel microarray entrapping SNP-immobilized GOX was fabricated using photolithography and successfully used for quantitative glucose detection. Copyright 2009 John Wiley & Sons, Ltd. [source]

Chemical Synthesis of Triple-Labelled Three-Helix Bundle Binding Proteins for Specific Fluorescent Detection of Unlabelled Protein

CHEMBIOCHEM, Issue 6 2005
Torun Engfeldt
Abstract Site-specifically triple-labelled three-helix bundle affinity proteins (affibody molecules) have been produced by total chemical synthesis. The 58 aa affinity proteins were assembled on an automated peptide synthesizer, followed by manual on-resin incorporation of three different reporter groups. An orthogonal protection strategy was developed for the site-specific introduction of 5-(2-aminethylamino)-1-naphthalenesulfonic acid (EDANS) and 6-(7-nitrobenzofurazan-4-ylamino)-hexanoic acid (NBDX), constituting a donor/acceptor pair for fluorescence resonance energy transfer (FRET), and a biotin moiety, used for surface immobilization. Circular dichroism and biosensor studies of the synthetic proteins and their recombinant counterparts revealed that the synthetic proteins were folded and retained their binding specificities. The biotin-conjugated protein could be immobilized onto a streptavidin surface without loss of activity. The synthetic, doubly fluorescent-labelled affinity proteins were shown to function as fluorescent biosensors in an assay for the specific detection of unlabelled human IgG and IgA. [source]