Background: The light absorption and emission characteristics of Gold Nanoparticles (GNPs) are exploited in detection and treatment of cancer. The properties of Nanoparticles (NPs) give them high potential for use in various medical applications, particularly in diagnostics and therapy where they promise increased sensitivity, speed, and costeffectiveness. The Ultraviolet-Visible and fluorescence properties of non-functionalized GNPs have not thus far been comprehensively documented. This study evaluated the absorption and fluorescence spectra for solutions of GNPs at different concentrations. Methods: The mean sizes of these GNPs were calculated from Transmission Electron Microscope (TEM) images, which were also used to study the morphology of the GNPs. UV-Visible and fluorescence measurements, were made from 250-700 nm using 1 cm quartz cuvettes. Results: When the GNP size changed from 10 nm to 50 nm, the maximum extinction of the Surface Plasmon Band (SPB) shifted from 517 nm to 532 nm in the visible region which may be attributed to the surface plasmon oscillation of free electrons. At constant GNP size, the absorbance was found to be proportional to the concentration of gold. This is because an increased number of GNPs also increases the total surface for surface plasmon resonance. The Photoluminescence (PL) band centre appears at 423 nm. An increase in fluorescence intensity with increase in GNP size was observed. At a fixed GNP size of 10 nm, and with increasing GNP concentration, the intensity of the emission band increased, which was consistent with the changes observed for the surface plasmon band of GNPs. Conclusions: The absorption intensity and maxima are particle size dependent. The surface plasmon resonance of the gold particles is red shifted (from 517 to 532 nm) with increasing particle size. These results indicate that the fluorescence intensity and the absorption band of GNPs were concentration and particle size dependent.
Background: Recently, use of nanotechnology in biomedical applications such as drug delivery and diagnostic and therapeutic tools has increased greatly. This study evaluated gold nanoparticle (GNPs)-induced nephrotoxic effects in rats in vivo, and examined protective effects of alpha-lipoic acid (α-Lip) and Vitamin E (Vit E) against nephrotoxicity, lipid peroxidation, and inflammatory kidney damage induced by GNPs. Materials and Methods: Twenty-four male Wistar-Kyoto rats (220-240 g, 12 weeks old) were dosed with 50 μL of 10 nm GNPs administered intraperitoneally with or without 200 mg/ kg/day Vit E or 200 mg/kg/day α-Lip. Serum was prepared for biochemical analyses. Kidney function was evaluated through measurement of creatinine (CR), uric acid (URIC), and blood urea nitrogen (BUN). Oxidative stress and lipid peroxidation were evaluated by measurement of reduced glutathione (GSH) and malondialdehyde (MDA) in kidney tissue homogenates. Results and Conclusions: The results showed a significant rise in serum kidney function biomarkers including urea, URIC, CR, and BUN in GNP-treated rats compared to normal control rats. Furthermore, GNPs led to decreased GSH and elevated MDA levels. Vit E or α-Lip supplementation showed a beneficial effect against nephrotoxicity, lipid peroxidation, and inflammatory kidney damage induced by GNPs. This study suggests that use of natural antioxidants in combination with GNPs may be a useful tool in preventing GNPs toxicity.
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