title: Ultra-sensitive immunosensor for beta-amyloid (1-42) using scanning tunneling microscopy-based electrical detection.
abstract: An ultra-sensitive immunosensor for beta-amyloid is crucial because beta-amyloid is an important challenging marker to detect for early diagnosis of Alzheimer's disease. In this study, a vertically configured electrical detection system was developed based on scanning tunneling microscopy (STM) to detect antigen-antibody binding events. This technique could be used to easily construct a multiple measurement system in a biochip. We utilized immunocomplexes comprised of the model protein, beta-amyloid (1-42), corresponding antibody fragments, and gold (Au) nanoparticles-antibody conjugates for an immunosensor for Alzheimer's disease. The electrical tunneling current between the STM tip and these complexes exhibited a peak-like pulse, the frequency of which depended on the density of the bound complexes on the surface. We could therefore quantitatively measure beta-amyloid (1-42) concentrations as low as 10fg/mL using periodogram analysis of the peak frequency. Since this method accurately quantified much smaller amounts of beta-amyloid (1-42) than traditional immunosensors, this system shows promise as an ultra-sensitive immunodetection method.
authors.affiliation: Department of Chemical & Biomolecular Engineering, Sogang University, #1 Shinsoo-Dong, Mapo-Gu, Seoul 121-742, Republic of Korea.
authors.forename: Da-Yeon
authors.initials: DY
authors.lastname: Kang
authors.forename: Jin-Ho
authors.initials: JH
authors.lastname: Lee
authors.forename: Byung-Keun
authors.initials: BK
authors.lastname: Oh
authors.forename: Jeong-Woo
authors.initials: JW
authors.lastname: Choi
mesh_terms: D016229:Amyloid beta-Peptides / Q000032:analysis*; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007118:Immunoassay / Q000295:instrumentation* / Q000379:methods; D016252:Microscopy, Scanning Tunneling / Q000295:instrumentation* / Q000379:methods; D010446:Peptide Fragments / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; C075222:amyloid beta-protein (1-42)