Detection of amyloid-?42 using a waveguide-coupled bimetallic surface plasmon resonance sensor chip in the intensity measurement mode.

ABSTRACT: The waveguide-coupled bimetallic (WcBiM) surface plasmon resonance (SPR) chip had been utilized in the intensity interrogation detection mode to detect amyloid-?42 (A?42), a biomarker of the Alzheimer disease. The SPR reflectance curve of the WcBiM chip has the narrower full-width-at-half-maximum (FWHM) compared with the SPR reflectance curve of the conventional gold (Au) chip, resulting in the steeper gradient. For the enhancement of resolution, the light source was fixed at an angle where the slope of the reflectance curve is the steepest, and the change in the reflectance was monitored. For the detection of A?42, the antibody of A?42 (anti-A?42) was immobilized on the WcBiM SPR chip using the self-assembled monolayer. The SPR responses, the average changes in the reflectance to the A?42 at the concentrations of 100 pg/ml, 250 pg/ml, 500 pg/ml, 750 pg/ml, 1,000 pg/ml, and 2,000 pg/ml were 0.0111%, 0.0305%, 0.0867%, 0.1712%, 0.3021%, and 0.5577%, respectively, for the three replicates. From linear regression analysis, the calibration curve indicated that the SPR response had a linear relation with A?42 with the concentration in the range of 100 pg/ml to 2,000 pg/ml. A control experiment showed the anti-A?42-modified surface of the WcBiM chip had a high specificity to A?42. Thus, the enhanced resolution by utilizing the WcBiM SPR chip in the intensity interrogation detection mode aids the diagnosis of the Alzheimer disease by detecting the A?42 around the criteria concentration (500 pg/ml) without any labeling.

SUBMITTER: Lee YK 

PROVIDER: S-EPMC4049661 | biostudies-literature | 2014

REPOSITORIES: biostudies-literature