title: High sensitivity detection of molecular recognition using magnetically labelled biomolecules and magnetoresistive sensors.
abstract: Small magnetoresistive spin valve sensors (2 x 6 microm(2)) were used to detect the binding of single streptavidin functionalized 2 microm magnetic microspheres to a biotinylated sensor surface. The sensor signals, using 8 mA sense current, were in the order of 150-400 microV for a single microsphere depending on sensor sensitivity and the thickness of the passivation layer over the sensor surface. Sensor saturation signals were 1-2 mV representing an estimated 6-20 microspheres, with a noise level of approximately 10 microV. The detection of biomolecular recognition for the streptavidin-biotin model was shown using both single and differential sensor architectures. The signal data compares favourably with previously reported signals for high numbers of magnetic microspheres detected using larger multilayered giant magnetoresistance sensors. A wide range of applications is foreseen for this system in the development of biochips, high sensitivity biosensors and the detection of single molecules and single molecule interactions.
authors.affiliation: INESC Microsystems and Nanotechnologies, R Alves Redol 9, 1000 Lisbon, Portugal. dgraham@inesc-mn.pt
authors.forename: D L
authors.initials: DL
authors.lastname: Graham
authors.forename: H A
authors.initials: HA
authors.lastname: Ferreira
authors.forename: P P
authors.initials: PP
authors.lastname: Freitas
authors.forename: J M S
authors.initials: JM
authors.lastname: Cabral
mesh_terms: D000936:Antigen-Antibody Complex / Q000032:analysis; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D001710:Biotin; D004867:Equipment Design; D008280:Magnetics / Q000295:instrumentation*; D008832:Microchemistry / Q000295:instrumentation / Q000379:methods; D008863:Microspheres; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013113:Spin Labels; D013194:Staining and Labeling / Q000379:methods*; D019809:Streptavidin / Q000032:analysis*; D014159:Transducers
chemical_list: D000936:Antigen-Antibody Complex; D013113:Spin Labels; D001710:Biotin; D019809:Streptavidin