Assembly of Polymers/Metal Nanoparticles and Their Applications as Medical Devices - Biosensors Nanotechnology - page 42

turned to the therapeutic possibilities for such materials. Structures which
behave as gene-regulating agents, drug carriers, imaging agents, and thera-
peutics have been designed and studied in the context of cells and many
diseases [30-32]. h ese structures are not simply chosen as alternatives to
molecule-based systems, but rather for their new physicochemical proper-
ties, which confer substantive advantages in cellular and medical applications.
Depending on their morphology, degree of aglomeration, and local
environment, gold nanoparticles can appear red, blue, or other colors
(Figure 2.3). h ese visible colors rel ect the underlying coherent oscillations
Increasing particle size
Increasing aspect ratio
Figure 2.3 Photographs of aqueous solutions of gold nanospheres (upper panels) and gold
nanorods (lower panels) as a function of increasing dimensions. Corresponding transmission
electron microscopy images of the nanoparticles are shown (all scale bars 100 nm) [1].