Magnetic iron oxide nanoparticles for biorecognition: evaluation of surface coverage and activity.
Modifying the surfaces of magnetic nanoparticles (MNPs) by the covalent attachment of biomolecules will enable their implementation as contrast agents for magnetic resonance imaging or as media for magnetically assisted bioseparations. In this paper we report both the surface coverage and the activity of IgG antibodies on MNPs. The antibodies were immobilized on gamma-Fe2O3 nanoparticles by conventional methods using aminopropyltriethoxy silane and subsequent activation by glutaraldehyde. Novel fluorescence methods were used to provide a quantitative evaluation of this well-known approach. Our results show that surface coverage can be stoichiometrically adjusted with saturated surface coverage occurring at approximately 36% of the theoretical limit. The saturated surface coverage corresponds to 34 antibody molecules bound to an average-sized MNP (32 nm diameter). We also show that the immobilized antibodies retain approximately 50% of their binding capacity at surface-saturated levels.
Koh
Isaac
I
Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742-2111, USA.
Wang
Xiang
X
Varughese
Bindhu
B
Isaacs
Lyle
L
Ehrman
Sheryl H
SH
English
Douglas S
DS
D000906:Antibodies / Q000737:chemistry*; D000918:Antibody Specificity; D005290:Ferric Compounds / Q000737:chemistry*; D005456:Fluorescent Dyes / Q000737:chemistry*; D008024:Ligands; D008280:Magnetics; D049329:Nanostructures; D013050:Spectrometry, Fluorescence; D013499:Surface Properties
D000906:Antibodies; D005290:Ferric Compounds; D005456:Fluorescent Dyes; D008024:Ligands; C000499:ferric oxide