Abstract
The long-term toxicity effects of gold nanoparticles (GNPs) on the proliferation and differentiation of a progenitor cell line, MG63 osteoblast-like cells, was investigated. These cells were treated for 20 hours with two media that contained 10 nm GNPs at concentrations of 1 ppm and 10 ppm. The mitosis of the GNP-treated MG63 was observed after at least 21 hours using dark-field and fluorescence microscopy. The TEM, LSCM and dark-field hyperspectral images indicated that the late endosomes in cells that contained aggregated GNPs were caused by vesicle fusion. Subsequently, after 21 days of being cultured in fresh medium, the specific nodule-like phenotypes and bone-associated gene expression of the treated MG63 cells exhibited the same behaviors as those of the control group. Statistically, after 21 days, the viability of the treated cells was identical to that of the untreated ones. During the cell death program analysis, the apoptosis and necrosis percentages of cells treated for 8 or fewer days were also observed to exhibit no significant difference with those of the untreated cells. In summary, our experiments show that the long-term toxicity of GNPs on the osteogenetic differentiation of MG63 is low. In addition, because of their low toxicity and non-biodegradability, GNPs can potentially be used as biomarkers for the long-term optical observation of the differentiation of progenitor or stem cells based on their plasmonic light-scattering properties.
Highlights
Molecular imaging is a potential method for detecting and imaging specific cells and molecules to understand their particular interactions in vivo
The energy-dispersive (EDS) spectrum of the gold nanoparticles (GNPs) shows that their surfaces do not contain a considerable number of oxygen atoms, which demonstrates that the GNPs utilized in the present study did not contain any specific functional groups even though they were synthesized via the citrate reduction of a gold salt (File S1)
Because the doubling time of the MG63 cells is approximately 24 hours, we treated MG63 with the two media for less than 24 hours to observe the effects of the concentration of GNPs on cell attachment and phenotype
Summary
Molecular imaging is a potential method for detecting and imaging specific cells and molecules to understand their particular interactions in vivo. This method has proven useful in proteomics and genomics research as well as for the diagnosis and therapy of certain diseases. Great effort has been devoted to the development of high-sensitivity and high-resolution optical nanoprobes with low detection limits. Among these new nanoprobes, MNPs, including gold nanoparticles (GNPs), gold nanorods and magnetic nanoparticles are promising biomarkers that have recently been developed. Because of the tunable SPR of GNPs, they have been investigated extensively for biomedical applications, including biosensing [3], molecular imaging [4,5,6,7] and photothermal therapy [8,9]
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