Abstract
The aim of this study was to evaluate the impact of multi-walled carbon nanotubes (MWCNTs with diameter in the range of 10–30 nm) before and after chemical surface functionalisation on macrophages response. The study has shown that the detailed analysis of the physicochemical properties of this particular form of carbon nanomaterial is a crucial issue to interpret properly its impact on the cellular response. Effects of carbon nanotubes (CNTs) characteristics, including purity, dispersity, chemistry and dimension upon the nature of the cell environment–material interaction were investigated. Various techniques involving electron microscopy (SEM, TEM), infrared spectroscopy (FTIR), inductively coupled plasma optical emission spectrometry, X-ray photoelectron spectroscopy have been employed to evaluate the physicochemical properties of the materials. The results demonstrate that the way of CNT preparation prior to biological tests has a fundamental impact on their behavior, cell viability and the nature of cell–nanotube interaction. Chemical functionalisation of CNTs in an acidic ambient (MWCNT-Fs) facilitates interaction with cells by two possible mechanisms, namely, endocytosis/phagocytosis and by energy-independent passive process. The results indicate that MWCNT-F in macrophages may decrease the cell proliferation process by interfering with the mitotic apparatus without negative consequences on cell viability. On the contrary, the as-prepared MWCNTs, without any surface treatment produce the least reduction in cell proliferation with reference to control, and the viability of cells exposed to this sample was substantially reduced with respect to control. A possible explanation of such a phenomenon is the presence of MWCNT’s agglomerates surrounded by numerous cells releasing toxic substances.
Highlights
Nanomaterials as the foundation of nanotechnology are increasing in importance due to the needs of different branches of industry and medicine for modern and improved performance products and medical devices
The inductively coupled plasma optical emission spectrometry (ICP-OES) method indicates that after purification of MWCNTs in acid solution the catalyst residue was reduced to 0.1 wt% for MWCNT after chemical treatment (MWCNT-F) (Table 1)
According to our previous works and the results presented by other authors the influence of metal residuals on in vitro cellular response is significantly lower than effect of the length of the nanotubes and their agglomerated form (Poland et al 2008; Fraczek et al 2008; Sanchez et al 2011; Zhao and Liu 2012)
Summary
Nanomaterials as the foundation of nanotechnology are increasing in importance due to the needs of different branches of industry and medicine for modern and improved performance products and medical devices. Other researchers in turn have indicated that nanotubes are biocompatible and have a positive impact on cell growth and proliferation and, may be used in tissue engineering (Shi et al 2007; Matsumoto et al 2007; Fraczek et al 2008). Due to their mobility potential in living systems, they may be successfully used as novel drug delivery systems for therapy and diagnosis (Xu et al 2008; Menard-Moyon et al 2010). Many studies indicate that biocompatibility of CNTs in both in vivo and in vitro studies may be attributed to various factors, including their lengths, functionality, their concentration, duration in the living body, catalyst impurity, agglomeration and even the dispersants used to dissolve the nanotubes
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