Abstract
BackgroundOne particularly exciting field of research involves the use of gold nanoparticles (GNPs) in the detection and treatment of cancer cells in the liver. The detection and treatment of cancer is an area in which the light absorption and emission characteristics of GNPs have become useful. Currently, there are no data available regarding the fluorescence spectra or in vivo accumulation of nanoparticles (NPs) in rat liver after repeated administration. In an attempt to characterise the potential toxicity or hazards of GNPs in therapeutic or diagnostic use, the present study measured fluorescence spectra, bioaccumulation and toxic effects of GNPs at 3 and 7 days following intraperitoneal administration of a 50 μl/day dose of 10, 20 or 50 nm GNPs in rats.MethodsThe experimental rats were divided into one normal group (Ng) and six experimental 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). A 50 μl dose of GNPs (0.1% Au by volume) was administered to the animals via intraperitoneal injection, and fluorescence measurements were used to identify the toxicity and tissue distribution of GNPs in vivo. Seventy healthy male Wistar-Kyoto rats were exposed to GNPs, and tissue distribution and toxicity were evaluated after 3 or 7 days of repeated exposure.ResultsAfter administration of 10 and 20 nm GNPs into the experimental rats, two fluorescence peaks were observed at 438 nm and 487 nm in the digested liver tissue. The fluorescence intensity for 10 and 20 nm GNPs (both first and second peaks) increased with the infusion time of GNPs in test rats compared to normal rats. The position of the first peak was similar for G1A, G2A, G1B, G2B, G3B and the normal (438 nm); that for G3A was shifted to a longer wavelength (444 nm) compared to the normal. The position of the second peak was similar for G1A, G1B, G2A, G2B and the control (487 nm), while it was shifted to a shorter wavelength for G3A (483 nm) and G3B (483 nm). The fluorescence intensity of the first and second peaks increased for G1A, G2A, G1B and G2B, while it decreased for G3A and G3B compared to the control.ConclusionsThe fluorescence intensity of GNPs varied with the number, size and shape of particles and with the ratio of surface area to volume in a given sample. Fluorescence intensity changes during infusion depended on the size and shape of GNPs, with smaller particles experiencing larger changes during the infusion time in addition to the quenching produced by the larger GNPs. It is likely that smaller particles, which have a much higher ratio of surface area to volume compared to larger particles, are more prone to aggregation and surface interaction with biological components. This study suggests that fluorescence intensity can be used to evaluate bioaccumulation and the toxicity of gold nanoparticles in rats.
Highlights
Nanoparticles (NPs) offer great promise for biomedical applications, in pharmaceutical delivery and novel diagnostic and therapeutic methods [1].Despite the many potential therapeutic benefits of nanoparticles, some studies indicate that certain nanoparticles, due to their small size and unique physical properties, may cause adverse effects [2,3]
Size and morphology of different gold nanoparticles (GNPs) The 10 and 20 nm GNPs showed spherical morphology with a narrow particle size distribution when dispersed in solution
The results of this study indicate that decreasing nanoparticle size, which produces an exponential increase in surface area relative to volume, may make the GNPs more self-reactive and more prone to interactions with surrounding molecules
Summary
Nanoparticles (NPs) offer great promise for biomedical applications, in pharmaceutical delivery and novel diagnostic and therapeutic methods [1].Despite the many potential therapeutic benefits of nanoparticles, some studies indicate that certain nanoparticles, due to their small size and unique physical properties, may cause adverse effects [2,3]. The size, surface area and dosage of particles all appear to play important roles in mediating nanoparticle toxicity. It has been proposed, for example, that the size of nanoparticles influences their adhesion to and interaction with living cells [4]. Metallic NPs can be made to exhibit a resonant response to a time-dependent magnetic field, producing a potentially useful energy transfer to the particles [5,6]. Such particles have been used as hyperthermic agents that deliver lethal amounts of thermal energy to targets such as tumours [7,8,9]. In an attempt to characterise the potential toxicity or hazards of GNPs in therapeutic or diagnostic use, the present study measured fluorescence spectra, bioaccumulation and toxic effects of GNPs at 3 and 7 days following intraperitoneal administration of a 50 μl/day dose of 10, 20 or 50 nm GNPs in rats
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