posted on 2013-09-17, 00:00authored byMichelle
A. Penn, David M. Drake, Jeremy D. Driskell
A rapid
and simple SERS-based immunoassay has been developed to
overcome diffusion-limited binding kinetics that often impedes rapid
analysis in conventional heterogeneous immunoassays. This paper describes
the development of an antibody-modified membrane as a flow-through
capture substrate for a nanoparticle-enabled SERS immunoassay to enhance
antibody–antigen binding kinetics. A thin layer of gold is
plated onto polycarbonate track-etched nanoporous membranes via electroless
deposition. Capture antibody is immobilized onto the surface of a
gold-plated membrane via thiolate coupling chemistry to serve as a
capture substrate. A syringe is then used to actively transport the
analyte and extrinsic Raman labels to the capture substrate. The fabrication
of the gold-plated membrane is thoroughly investigated and established
as a viable capture substrate for a SERS-based immunoassay in the
absence of sample/SERS label flow. A syringe pump is used to systematically
investigate the effect of flow rate on antibody–antigen binding
kinetics and demonstrate that active transport to the capture membrane
surface expedites antibody–antigen binding. Mouse IgG and goat
anti-mouse
IgG are selected as a
model antigen–antibody system to establish proof of principle.
It is demonstrated that the assay for mouse IgG is reduced from 24
h to 10 min and a 10-fold improvement in detection limit is achieved
with the flow assay developed herein relative to the passive, i.e.,
no flow, assay. Moreover, mouse serum is directly analyzed and IgG
level is determined using the flow assay.