title: Magnetic nanoparticle-enhanced biosensor based on grating-coupled surface plasmon resonance.
abstract: A highly sensitive surface plasmon resonance (SPR) biosensor employing magnetic nanoparticle (MNP) assays is presented. In the reported approach, MNPs simultaneously served as "vehicles" for rapid delivery of target analyte from a sample to the sensor surface and as labels increasing the measured refractive index changes that are associated with the binding of target analyte. An optical setup based on grating-coupled surface plasmon resonance (GC-SPR) was used with a magnetic field gradient applied through the sensor chip for manipulating with MNPs on its surface. Iron oxide MNPs and a sensor surface with metallic diffraction grating were modified with antibodies that specifically recognize different epitopes of the analyte of interest. The sensitivity of the biosensor was investigated as a function of mass transport of the analyte to the sensor surface driven by diffusion (free analyte) or by the magnetic field gradient (analyte bound to MNPs). Immunoassay-based detection of β human chorionic gonadotropin (βhCG) was implemented to evaluate the sensitivity of the MNP-enhanced GC-SPR biosensor scheme. The results reveal that the sensitivity of βhCG detection was improved by 4 orders of magnitude compared with the regular SPR sensor with direct detection format, and a limit of detection below pM was achieved.
authors.affiliation: Health & Environment Department, AIT Austrian Institute of Technology, Vienna, Austria.
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.forename: Jakub
authors.initials: J
authors.lastname: Dostalek
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Knoll
mesh_terms: D000906:Antibodies / Q000737:chemistry / Q000378:metabolism*; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000032:analysis* / Q000378:metabolism; D004058:Diffusion; D005260:Female; D005290:Ferric Compounds / Q000737:chemistry; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D057230:Limit of Detection; D060526:Magnetic Fields; D053758:Nanoparticles / Q000737:chemistry; D015203:Reproducibility of Results; D020349:Surface Plasmon Resonance / Q000379:methods*
chemical_list: D000906:Antibodies; D018997:Chorionic Gonadotropin, beta Subunit, Human; D005290:Ferric Compounds; C000499:ferric oxide