Start where you're curious.
May 2017 to May 2019
Xu Lab
Study of Cytotoxic and Therapeutic Effects of Silver Nanoparticles Against Colon Tumor Cells
Rebecca M. Richardson, Krishna K. Raut, Tatiana Zvonareva, Preeyaporn Songkiatisak, Pavan Cherukuri, and X. Nancy Xu*
Department of Chemistry and Biochemistry, Old Dominion University, Norfolk, VA 23529 *xhxu@odu.edu https://ww2.odu.edu/~xhxu/
This study explored the cytotoxic and therapeutic potential of silver nanoparticles (AgNPs) against human colon tumor cells. We synthesized and characterized 43.2 ± 12.1 nm AgNPs, confirming their stability in cell culture medium for up to 120 hours. Using time- and dose-dependent exposure models, we found that treatment with AgNPs (2.5–20 pM) significantly reduced tumor cell growth after 120 hours, while control samples treated with nanoparticle-free supernatant showed no such inhibition.
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Further investigation revealed that AgNPs disrupted tumor cell viability through multiple mechanisms, including cell cycle arrest, genotoxicity, and induction of apoptosis. Uptake studies showed a preferential accumulation of nanoparticles in the cytoplasm over the nucleus, with intracellular nanoparticle counts increasing through 72 hours before declining—suggesting a possible cellular efflux response.
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These findings provide valuable insight into the cytotoxic behavior of AgNPs and support their promise as stable, effective agents for future cancer nanotherapeutics and diagnostic tools.
Characterization of 43nm Ag NPs size, shape, and LSPR spectra dispersed in medium
(A) HRTEM representative image of single Ag NPs distribution show mostly spherical shape, with occasional rods, scale bar = 50 nm. (B) A histogram of the Ag NPs measured from HRTEM images shows an average diameter of 43.2 ± 12.1 nm for over 100 NPs. (C) Single blue, green, and red particles were observed in dark-field imaging of 20pM Ag NPs in medium. (D) LSPR spectra of single Ag NPs in medium showed λ max at (a) 471 nm, (b) 536 nm and (C) 628 nm, which is consistent with the blue, green, and red Ag NPs observed in (C).
Stability of 43nm Ag NPs in medium at 37°C for 120 hr using DFOMS
(A) Average number of NPs per location over time. Nanoparticles appear stable with no statistically significant difference in number of Ag NPs observed over time until 170 h (P<0.05). (B) Average number of NP color distribution in medium at (a) 3, (b) 72, and (c) 120 h. No statistically significant difference among the distribution of individual colors over time until 170 (d) h (P<0.05).
Study of time and dose dependent inhibitory effects of 43nm Ag NPs on HT-29 colon tumor cells
Representative optical Images of cells on flask surface, in medium containing (A) 0pM, (B) supernatant, (C) 2.5pM, (D) 5pM, (E) and 20pM Ag NPs, at (a) 4, (b) 24, (c) 48, (d) 72, (e) 96, and (f) 120 h. Scale bar = 50µm.
Study of 43nm Ag NPs cytotoxicity effects on HT-29 colon tumor cells
(A) number of cells cultured in medium with 0pM (a), supernatant (b), 2.5pM (c), 5pM (d), and 20pM (e) Ag NPs. There was no statistically significant difference found in the number of cells for control (a) and supernatant (b) or the 5pM (c) and 20pM (d) at any time point. There was a significant difference in the number of control cells compared to 2.5pM, 5pM, and 20pM Ag NP treated cells after 120 h (P<0.05).
Study of single HT-29 colon tumor cells and the effects of Ag NPs on morphology and viability
(A) Optical images of coverslip cultured cells in medium containing 0pM (a), supernatant (b), and 20pM AgNPs (c) for 170 h, show that the Ag NPs had an evident effect on the cellular morphology. Fluorescence imaging, using mitotracker orange (B), of cells treated with 0pM, supernatant (b), and 20pM AgNPs (c), revealed (B) that the cells are viable, scale bar = 5µm.
Study and imaging of intracellular single Ag NPs inside single live colon tumor cell’s cytoplasm and nucleus
(A) Optical images of single cells cultured on coverslips with 20pM AgNPs. AgNPs are distributed in both the cytoplasm and nucleus (a) and just the cytoplasm (b). (B) The total number of AgNPs observed in the cytoplasm, in comparison to the nuclei, was higher. The total number of intracellular NPs in the cytoplasm (a) decreased after 80 h, but the number of NPs in the nucleus (b) had little fluctuation, scale bar = 10 µm.
Characterization of Ag NP induce DNA damage in HT-29 colon tumor cells
(A) Fluorescence images of single cell’s DNA stained with ethidium bromide and characterized with comet assay (a) 0pM, (b) supernatant, (c) 5pM, and (d) 20pM, scale bars=10 µm. (B) Percent of cells in 5pM and 20pM treated cells where DNA damage was observed with (a) comet tail, and (b) no tail. (C) Length of comet tails observed in 5 and 20pM cells.
Correlation between degree of DNA damage and Ag NP uptake in 20pM treated tumor cells
(A) Representative image of HT-29 cells with and without comet tail at 40x objective. (B) Ag NP uptake of cells depicted in figure (A) at 100x objective (a) comet tail, and (b) no comet tail. (C) Average number of Ag NPs found per 20pM treated cell with tail, 11 ± 2.8 NPs, or without tail 4 ± 0.6 NPs. (D) Multispectral image of 20pM treated cell, and (E) LSPR spectra of green Ag NP, shown in figure D, with λmax at (a) 617.8, (b) 765.0, and (c) 794.8 nm. Scale bar figure (A) 20 nm, (B) 10 nm, and (D) 5 nm.