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Proceedings Paper

Probing mass-transport and binding inhomogeneity in macromolecular interactions by molecular interferometric imaging
Author(s): Ming Zhao; Xuefeng Wang; David Nolte
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Paper Abstract

In solid-support immunoassays, the transport of target analyte in sample solution to capture molecules on the sensor surface controls the detected binding signal. Depletion of the target analyte in the sample solution adjacent to the sensor surface leads to deviations from ideal association, and causes inhomogeneity of surface binding as analyte concentration varies spatially across the sensor surface. In the field of label-free optical biosensing, studies of mass-transport-limited reaction kinetics have focused on the average response on the sensor surface, but have not addressed binding inhomogeneities caused by mass-transport limitations. In this paper, we employ Molecular Interferometric Imaging (MI2) to study mass-transport-induced inhomogeneity of analyte binding within a single protein spot. Rabbit IgG binding to immobilized protein A/G was imaged at various concentrations and under different flow rates. In the mass-transport-limited regime, enhanced binding at the edges of the protein spots was caused by depletion of analyte towards the center of the protein spots. The magnitude of the inhomogeneous response was a function of analyte reaction rate and sample flow rate.

Paper Details

Date Published: 16 February 2009
PDF: 7 pages
Proc. SPIE 7188, Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications VI, 71880O (16 February 2009); doi: 10.1117/12.809500
Show Author Affiliations
Ming Zhao, Purdue Univ. (United States)
Xuefeng Wang, Purdue Univ. (United States)
David Nolte, Purdue Univ. (United States)

Published in SPIE Proceedings Vol. 7188:
Nanoscale Imaging, Sensing, and Actuation for Biomedical Applications VI
Alexander N. Cartwright; Dan V. Nicolau, Editor(s)

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