Gold nanorods are excellent candidate as biosensing materials because they are highly refractive index sensitive to trace amount of bio-molecules. The index sensitivity and figure of merit of gold nanorods are closely related to their morphology details, for example, the size, aspect ratio and end profile.
Shape- and Size-Dependent Refractive Index Sensitivity of Gold Nanoparticles [PDF]
Contrast Agents for SERS Labeling and Imaging
SERS was proven to be a superior method for bio-labelling and imaging base on laser scanning microscopy. Gold nanorods are perfect candidate as contrast agents for SERS labeling and imaging of live cells and tissues because of their high Raman luminance under NIR laser and excellent chemical inertia.
Gold nanorods with suitable width and aspect ratios can absorb strongly in the NIR region, which enables them for photothermal cancer therapy. The photothermal conversion efficiencies of gold nanorods are strongly dependent on their morphology.