Despite the many benefits of nanotechnology, some studies indicate that certain nanoparticles may cause adverse effects because of their small size and unique properties. The aim of the present study was to elucidate the period effects of intraperitoneal administration of different gold GNP sizes on the rat kidney tissue in vivo using fluorescence spectroscopy. The experimental rats were divided into control and six groups (G1A, G1B, G2A, G2B, G3A and G3B; G1: 20 nm; G2: 10 nm; G3: 50 nm; A: infusion of GNPs for 3 days; B: infusion of GNPs for 7 days). To investigate the period effects of GNPs 10, 20 and 50 nm on the kidney tissue of rats, 50 µl dose of GNPs (of concentration 0.1% Au) were intraperitonealy injected into rats for periods of 3 and 7 days to identify the toxicity and tissue distribution of GNPs in vivo using fluorescence measurements. GNPs of sizes 10 and 20 nm show spherical morphology with good particle size distribution dispersed in the solution while GNPs of size 50 nm have no spherical shape, but they have hexagonal shape. At the infusion period of 3 days, the fluorescence intensity of the 1st peaks increased for G1A and decreased for G2A and G3A compared with the control while the fluorescence intensity of the 2nd peaks decreased for G1A, G2A and G3A compared with the control. At the infusion period of 7 days, the fluorescence intensity of the 1st and 2nd peaks increased for G1B and G2B and sharply decreased for G3B compared with the control. At the infusion periods of 3 and 7 days, the fluorescence intensity of the 1st peaks increased for G1A, G1B and G2B and decreased for G2A, G3A and G3B compared with the control while the fluorescence intensity of the 2nd peaks decreased for G1A, G1B, G2A, G2B and G3A compared with the control. Fluorescence intensity of GNPs varied with the GNP size. The decrease in fluorescence intensity may be attributed to size, shape, number of GNPs, quenching of 50 nm GNPs, surface area of GNPs and slow clearance for GNPs of 10 and 20 nm through urine and bile from the kidney. Moreover, decreasing size may lead to an exponential increase in surface area relative to volume, thus making the GNPs surface more reactive on itself (aggregation) and to its surrounding environment (biological components). Size and shape of GNPs may be related to their useful characters and also plays a key role in toxicity. The alterations of accumulation in the kidney tissue, depending on GNP size, which may be mediated by dynamic protein binding and exchange. A better understanding of these mechanisms will improve drug delivery and period and dose estimation used in the risk assessment.
Key words: Gold nanoparticles, sizes, period effects, kidney tissue, fluorescence spectroscopy.
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