Elsevier

Chemical Physics Letters

Volume 463, Issues 1–3, 22 September 2008, Pages 145-149
Chemical Physics Letters

Challenge in understanding size and shape dependent toxicity of gold nanomaterials in human skin keratinocytes

https://doi.org/10.1016/j.cplett.2008.08.039Get rights and content

Abstract

As the nanotechnology field continues to develop, assessing nanoparticle toxicity is very important for advancing nanoparticles for biomedical application. Here we report cytotoxicity of gold nanomaterial of different size and shape using MTT test, absorption spectroscopy and TEM. Spherical gold nanoparticles of different sizes are not inherently toxic to human skin cells, but gold nanorods are highly toxic due to the presence of CTAB as coating material. Due to toxicity of CTAB, and aggregation of gold nanomaterials in the presence of cell media, we have demonstrated that it is difficult to understand the cytotoxicity of gold nanomaterials individually.

Graphical abstract

Assessing nanoparticle toxicity is very important for advancing nanoparticles for real life application. This Letter demonstrates that due to CTAB toxicity, and aggregation of gold nanomaterials in the presence of cell media, it is a real challenge to study the cytotoxicity of gold nanomaterials individually.

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Introduction

The nanoscience revolution that sprouted throughout the 1990s is having promises to benefit society [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24]. Since their size scale is similar to that of biological molecules (e.g., proteins, DNA) and structures (e.g., viruses and bacteria), enormous interest is growing to exploit nanoparticles for various biomedical applications [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24]. Due to valuable size and shape dependent properties, gold nanoparticles have been exploited as tools in biology for the last fifteen years [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24]. Their high electron density has made them popular labels in electron microscopy, and because their surface properties enable a great variety of functionalization procedures. Having extremely small size with highest possible surface area enables them to access a variety of biological environments. These advantages, along with the universal biocompatibility, gold nanoparticles are promising to be used as vehicles for drug and gene delivery. Furthermore, gold nanoparticles have recently been demonstrated in cell imaging, targeted drug delivery, and cancer diagnostics and therapeutic applications [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24]. As nanotechnology field continues to develop, studies on the cytotoxicity of nanoparticles, with respect to their size and shape, are required in order to advance nanotechnology for biomedical applications. This will be important for assessing nanoparticle toxicity, for advancing nanoparticles for imaging, drug delivery, and therapeutic applications and for designing multifunctional nanoparticles. Though nanoparticle production has been estimated to increase from 2300 tons produced today to 58 000 tons by 2020, it is surprising that knowledge on the toxicity effect of nanoparticle exposure is in infancy and also reported results are confusing [25], [26], [27], [28], [29], [30]. Driven by the need, we report the systematic study of cytotoxicity of gold nanomaterial of different size and shape.

Section snippets

Experimental

Gold nanoparticles of different particle sizes were synthesized using the citrate reduction method as reported recently [9], [10], [11], [12], [13], [14], [15], [16].

Transmission electron microscope (TEM) images and UV–Vis absorption spectra were used to characterize the nanoparticles, as we reported recently [9], [10], [11], [12], [13], [14], [15], [16]. The particle concentration was measured by UV–Vis spectroscopy using molar extinction coefficients at the wavelength of maximum absorption of

Results and discussion

The cell viabilities for gold nanoparticles of different sizes are shown in Fig. 2. Chithrani et. al. [29] have measured the intracellular uptake of different sizes and shapes of colloidal gold nanoparticles. Their results show that gold nanoparticles and nanorods are capable of entering the cells. The cellular uptake increases with incubation time until it is saturated at 8 h.

To make sure that cellular uptake reaches maximum, all our results are for 24 h incubation. As shown in Fig. 2A, no

Acknowledgements

We wish to thank NSF-PREM grant # DMR-0611539, NSF-MRI grant # 0421406 for their generous funding. We thank Sara H. Bayley, MRSEC Instrumentation Facilities Coordinator, University of Southern Mississippi for helping to acquire TEM data. We also thank reviewers whose valuable suggestion improved the quality of the manuscript.

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