title: Superparamagnetic bead interactions with functionalized surfaces characterized by an immunomicroarray.
abstract: Magneto-resistive sensors capable of detecting superparamagnetic micro-/nano-sized beads are promising alternatives to standard diagnostic assays based on absorbance or fluorescence and streptavidin-functionalized beads are widely used as an integral part of these sensors. Here we have developed an immunomicroarray for systematic studies of the binding properties of 10 different micro-/nano-sized streptavidin-functionalized beads to a biotin substrate immobilized on SiO(2) with or without surface modification. SiO(2) surface cleaning, immobilized substrate concentration and surface blocking conditions were optimized. Polyethylene glycol-based surfaces with different end groups on the anchor molecule, 2,4,6-trichloro-1,3,5-triazine (TsT), were synthesized and compared with the standard (3-aminopropyl)triethoxysilane (APTS)/glutaraldehyde chemistry. APTS/glutaraldehyde, directly linked TsT and bare H(2)O(2)-activated SiO(2) performed better than polyethylene glycol-modified surfaces. Two beads, Masterbeads and M-280 beads, were found to give superior results compared with other bead types. Antibody/antigen interactions, illustrated by C-reactive protein, were best performed with Masterbeads. The results provide important information concerning the surface binding properties of streptavidin-functionalized beads and the immunomicroarray can be used when optimizing the performance of bead-based biosensors.
authors.affiliation: Department of Micro- and Nanotechnology, Technical University of Denmark, DTU Nanotech, Kongens Lyngby, Denmark.
authors.forename: Peter Durand
authors.initials: PD
authors.lastname: Skottrup
authors.forename: Mikkel Fougt
authors.initials: MF
authors.lastname: Hansen
authors.forename: Jacob Moresco
authors.initials: JM
authors.lastname: Lange
authors.forename: Maria
authors.initials: M
authors.lastname: Deryabina
authors.forename: Winnie Edith
authors.initials: WE
authors.lastname: Svendsen
authors.forename: Mogens Havsteen
authors.initials: MH
authors.lastname: Jakobsen
authors.forename: Martin
authors.initials: M
authors.lastname: Dufva
mesh_terms: D015374:Biosensing Techniques; D001710:Biotin / Q000737:chemistry / Q000378:metabolism; D002097:C-Reactive Protein / Q000378:metabolism; D007118:Immunoassay / Q000379:methods*; D008280:Magnetics; D008422:Materials Testing; D046228:Microarray Analysis / Q000379:methods*; D008863:Microspheres; D015394:Molecular Structure; D011092:Polyethylene Glycols / Q000737:chemistry; D012710:Serum Albumin, Bovine / Q000378:metabolism; D012822:Silicon Dioxide / Q000737:chemistry; D019809:Streptavidin / Q000737:chemistry / Q000378:metabolism; D013499:Surface Properties
chemical_list: D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols; D001710:Biotin; D012822:Silicon Dioxide; D002097:C-Reactive Protein; D019809:Streptavidin