Uptake and intracellular accumulation of diamond nanoparticles – a metabolic and cytotoxic study

Abstract

Diamond nanoparticles, known as nanodiamonds (NDs), possess several medically significant properties. Having a tailorable and easily accessible surface gives them great potential for use in sensing and imaging applications and as a component of cell growth scaffolds. In this work we investigate in vitro interactions of human osteoblast-like SAOS-2 cells with four different groups of NDs, namely high-pressure high-temperature (HPHT) NDs (diameter 18–210 nm, oxygen-terminated), photoluminescent HPHT NDs (diameter 40 nm, oxygen-terminated), detonation NDs (diameter 5 nm, H-terminated), and the same detonation NDs further oxidized by annealing at 450 °C. The influence of the NDs on cell viability and cell count was measured by the mitochondrial metabolic activity test and by counting cells with stained nuclei. The interaction of NDs with cells was monitored by phase contrast live-cell imaging in real time. For both types of oxygen-terminated HPHT NDs, the cell viability and the cell number remained almost the same for concentrations up to 100 µg/mL within the whole range of ND diameters tested. The uptake of hydrogen-terminated detonation NDs caused the viability and the cell number to decrease by 80–85%. The oxidation of the NDs hindered the decrease, but on day 7, a further decrease was observed. While the O-terminated NDs showed mechanical obstruction of cells by agglomerates preventing cell adhesion, migration and division, the H-terminated detonation NDs exhibited rapid penetration into the cells from the beginning of the cultivation period, and also rapid cell congestion and a rapid reduction in viability. These findings are discussed with reference to relevant properties of NDs such as surface chemical bonds, zeta potential and nanoparticle types.

Diamond Nanoparticles Downregulate Expression of CycD and CycE in Glioma Cells

“…The medical use of NDs is probable because of their low cytotoxicity and high biological activity [9]. Several authors have reported a lack of toxic effects that manifest in the forms of inflammation and activation of macrophages [10], and symptoms of systemic toxicity after ND treatment in rats [11,12], but have also noted uptake and intracellular accumulation of NDs [13], activation of cell death (both apoptotic and necrotic) [14], and redox homeostasis disorders [15]. Diamond nanoparticles were also tested for their application in cancer chemotherapy.…”

Applications of Nanocellulose/Nanocarbon Composites: Focus on Biotechnology and Medicine

“…Nanodiamonds have been considered to be relatively nontoxic in comparison with other carbon nanoparticles. However, as shown in our earlier studies, hydrophobic, hydrogen-terminated and positively-charged diamond nanoparticles can enter the cells, impair their growth and cause cell death [152,156]. The mechanism of cell damage by nanodiamonds is by generating ROS, and by excessive delivery of sodium ions adsorbed on the nanodiamond surface [168].…”

“…Diamond is an allotrope of carbon, consisting of carbon atoms arranged in a cubic crystal structure covalently bonded in sp 3 hybridization (Figure 4a). Like all nanostructured materials, nanodiamonds or diamond nanoparticles are defined as features not exceeding 100 nm in at least one dimension, although some larger diamond particles, i.e., 125-210 nm, are still referred to as nanodiamonds (for a review, see [152]). At the same time, the size of ultrananocrystalline diamond particles is 3-5 nm [153,154].…”

“…The most widely used techniques are detonation of carbon-containing explosives in an oxygen-deficit environment and microwave-enhanced plasma chemical vapor deposition (MECVD). Other techniques include the radiofrequency plasma-assisted chemical vapor deposition (PACVD) method, milling of diamond microcrystals, hydrothermal synthesis, ion bombardment, laser bombardment, ultrasound synthesis and electrochemical synthesis (for a review, see [10,[152][153][154][155][156]). Nanodiamonds are considered to be the most advanced carbon materials in the world.…”

“…The chemical properties of nanodiamonds include low chemical reactivity and resistance to liquid-and gas-phase oxidations. However, nanodiamonds can be doped with various atoms, and their surface can be functionalized by various atoms, chemical groups and (bio)molecules ( [152,153,157,158]; for a review, see [10][11][12][13][14][15]155]). Scheme of a nanodiamond (a) and of the preparation and structure of nanocellulose/nanodiamond composites (b).…”