Chemically modified spherical gold nanoparticles have been used as extrinsic labels for surface enhanced Raman scattering (SERS) detection of surface based assays.  Rod-shaped gold nanoparticles should provide higher sensitivity and potentially stronger binding via multivalent interactions.  The challenge in employing gold nanorods for this application is the replacement of the shape directing surfactant layer on the surface.  We have developed a modification procedure to replace the cetyltrimethylammonium bromide (CTAB) layer on gold nanorods with a self-assembled monolayer (SAM) teminated with ethylene glycol (EG) and COOH groups.  The nanorods are made SERS active by place exchange with 4-nitrobenzenethiol (NBT).  We will present results that track the modification procedure.  Antibodies are conjugated to the nanorods through the terminal �COOH group.  The antibody conjugated nanorods were used for SERS readout in sandwich immunoassays and provide extremely low detection limits.  A direct comparison with spherical nanoparticles will be presented.

Modified gold nanorods as extrinsic surface enhanced Raman labels for bioassays

243rd National Meeting (2012)

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