Freezing and post-thaw apoptotic behaviour of cells in the presence of palmitoyl nanogold particles

Document Type

Article

Publication Date

5-16-2007

Abstract

The aim of this study was to evaluate the freezing response of HeLa and Jurkat cells in the presence of commercially available nanoparticles, NPs (Palmitoyl Nanogold®, Nanoprobes). The cells were incubated with NPs for either 5 min or 3 h, and a calorimeter technique was then used to generate the volumetric shrinkage response during freezing at 20°C min-1. Concomitantly, we also examined the effect of a commonly used cryoprotectant, dimethylsulfoxide, DMSO (10% v/v ratio) on the freezing response of HeLa and Jurkat cells. By fitting a model of water transport to the experimentally determined volumetric shrinkage data, the reference hydraulic conductivity, Lpg, (μm/min-atm) and activation energy, ELp, (kcal mol-1) were obtained. For HeLa cells, the values of Lpg ranged from 0.08 to 0.23 νm/min-atm, while ELp ranged from 10.9 to 37.4 kcal mol-1. For Jurkat cells these parameter values ranged from 0.05 to 0.16 μm/min-atm and 9.5 to 35.9 kcal mol-1. A generic optimal cooling rate equation was then used to predict the optimal rates of freezing HeLa and Jurkat cells in the presence and absence of DMSO and NPs. The post-thaw viability and apoptotic response of HeLa and Jurkat cells was further investigated by cooling cells at three rates in the presence and absence of DMSO and NPs using a commercially available controlled rate freezer. Jurkat cells treated in this manner demonstrated an increase in their adhesive properties after 18 h incubation and adhered strongly to the bottom of the culture plate. This observation prevented further analysis of Jurkat apoptotic and necrotic post-thaw responses. There was no significant effect of NPs or DMSO alone on HeLa cell viability prior to freezing. The post-thaw results from HeLa cells show that the NPs increased the measured post-freeze apoptotic response when cooled at 1°C min-1, suggesting a possible therapeutic use of NPs in cryodestructive procedures. © IOP Publishing Ltd.

Publication Source (Journal or Book title)

Nanotechnology

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