title: An aptamer-based quartz crystal protein biosensor.
abstract: We developed a quartz crystal biosensor designed to detect concentrations and ligand affinity parameters of free unlabeled proteins in real time. Using a model system with human IgE as the analyte and single-stranded DNA aptamers or an anti-IgE antibody as immobilized ligands, we could demonstrate that aptamers were equivalent to antibodies in terms of specificity and sensitivity. Both receptor types selectively detected 0.5 nmol/L of IgE. In addition, the aptamer receptors tolerated repeated affine layer regeneration after ligand binding and recycling of the biosensor with little loss of sensitivity. Because of the small size and nonprotein nature of the aptamers, they were immobilized in a dense, well-oriented manner, thus extending the linear detection range to 10-fold higher concentrations of IgE. In addition to demonstrating for the first time that an aptamer-based biosensor can specifically and quantitatively detect an analyte in various complex protein mixes, the aptamer-ligand proved to be relatively heat resistant and stable over several weeks. Since aptamers consist of nucleic acids, well-established chemistry can be applied to produce optimized affine layers on biosensors that may be developed to specifically detect proteins in solution for analysis of proteomes.
authors.affiliation: Institute of Medical Microbiology and Hygiene, University of Regensburg, Germany.
authors.forename: Michael
authors.initials: M
authors.lastname: Liss
authors.forename: Birgit
authors.initials: B
authors.lastname: Petersen
authors.forename: Hans
authors.initials: H
authors.lastname: Wolf
authors.forename: Elke
authors.initials: E
authors.lastname: Prohaska
mesh_terms: D000888:Antibodies, Anti-Idiotypic / Q000276:immunology; D015374:Biosensing Techniques / Q000379:methods*; D004277:DNA, Single-Stranded / Q000378:metabolism; D004867:Equipment Design; D006046:Gold; D007073:Immunoglobulin E / Q000032:analysis / Q000378:metabolism; D011485:Protein Binding; D011506:Proteins / Q000032:analysis* / Q000378:metabolism; D011791:Quartz; D012680:Sensitivity and Specificity
chemical_list: D000888:Antibodies, Anti-Idiotypic; D004277:DNA, Single-Stranded; D011506:Proteins; D011791:Quartz; D007073:Immunoglobulin E; D006046:Gold