Abstract:
A bimetallic nanorod dimer biosensor based on localized surface plasmon resonance
(LSPR) has been proposed in this thesis. Larger absorption and stronger electric eld
coupling have been achieved when a gold (Au) core nanorod is coated with silver (Ag)
shell layer (Au@Ag). The optical response, e.g., dielectric function of this bimetallic
monomer has been modeled analytically with the help of Clausius-Mossotti equation.
Using the developed model, the polarizability, dipole moment, and absorption crosssection
of the Au@Ag nanorod dimer have been calculated. In order to investigate
the molecular sensitivity, this bimetallic dimer has been simulated without and with
the presence of label-free proteins using the nite di erence time domain (FDTD)
technique. Lysozyme (Lys), human serum albumin (HSA), human
-immunoglobulin
(IgG), adenomatous polyposis coli (APC) and human brinogen (Fb) proteins have
been used to calculate the resonance shifts from the FDTD simulations. In addition,
e ects of physical parameters, orientations and environment of Au@Ag nanorods in
the dimer system have also been studied through peak shifts for an APC protein
sample. The shift values from the proposed structure have been found to be 6%{
30% larger compared to the conventionally used Au dimer sensors. Therefore, better
sensitivity performance of the Au@Ag nanorod dimers would pave the way for its
extensive research in biochemical and pharmaceutical industries.
