Gold Nanoparticles

Gold nanoparticles are indicated in the treatment ofrheumatoid arthritis as anti-inflammatory agents. On the other hand, radioactive gold microparticles are directed to cancer therapy as local radioisotope [14]. Silica-coated gold nanoparticles can deliver excess heat and active agent simultaneously to the tumor cells to achieve superior efficacy [15]. Similarly, gadolinium-loaded dendrimer-entrapped gold nanoparticles (Gd-Au DENPs) contain gold nanoparticles and gadolinium entrapped within the same nanoparticle carrier system. These dual-loaded inorganic nanoparticles may aid in simultaneous magnetic resonance (MR) and computed tomography (CT) imaging of kidney, heart, liver, and other biological systems [16]. A combination of gold nanoparticles with X-ray has been prepared to induce DNA damage and cytotoxicity of tumor cells. Fig. 14.4 demonstrates model tumor cells and illustrates the mean displacement of gold nanoparticles from the nuclear boundary. Moreover, the size of the cell nuclei can be mapped (Fig. 14.4) by calculating the intensity of gold, which is directly proportional to the ionization of gold particles causing DNA damage.

Figure 14.4 (A) Cells incubated with 500 mg/mL gold particles for 24 h before being fixed and stained with 4',6-diamidino-2-phenylindole (DAPI). Image contains both the surface plasmon resonance signal from two-photon interaction with gold particles (orange, black in print versions) and nuclei regions (blue, dark gray in print versions). The gold nanoparticles are observed in the cytoplasmic regions with some of the gold particles accumulating close to the nuclear boundary regions. (B) Nuclei boundaries produced in image analysis by a varying binary threshold. The automatic threshold determined by ImageJ (white) in comparison with a lower threshold (green, white in print versions) and higher threshold (red, light gray in print versions). (C) Integrated gold signal of 20 cells for increasing distance from the nuclear membrane for the three thresholds chosen in (B). The automatic threshold outline (black line) produces a maximum gold intensity at 0.5 mm outside the nuclear membrane. The gold intensity reduces significantly across the membrane (distance = 0) and the gold signal within the nucleus (distances < 0) is consistent with the assumption that all of the gold is outside the nucleus, instead reflecting the measured point spread function for the gold image of 0.5 mm. The integration was done taking account of the number of pixels in the image at each distance from the nuclear membrane. Hence to a good approximation the intensity is equivalent to the relative density of gold nanoparticles.