Nano-hydroxyapatite and Nano-titanium Dioxide Exhibit Different Subcellular Distribution and Apoptotic Profile in Human Oral Epithelium

Abstract

Nanomaterials (NMs) such as titanium dioxide (nano-TiO2) and hydroxyapatite (nano-HA) are widely used in food, personal care, and many household products. Due to their extensive usage, the risk of human exposure is increased and may trigger NMs specific biological outcomes as the NMs interface with the cells. However, the interaction of nano-TiO2 and nano-HA with cells, their uptake and subcellular distribution, and the cytotoxic effects are poorly understood. Herein, we characterized and examined the cellular internalization, inflammatory response and cytotoxic effects of nano-TiO2 and nano-HA using TR146 human oral buccal epithelial cells as an in vitro model. We showed both types of NMs were able to bind to the cellular membrane and passage into the cells in a dose dependent manner. Strikingly, both types of NMs exhibited distinct subcellular distribution profile with nano-HA displaying a higher preference to accumulate near the cell membrane compared to nano-TiO2. Exposure to both types of NMs caused an elevated reactive oxygen species (ROS) level and expression of inflammatory transcripts with increasing NMs concentration. Although cells treated with nano-HA induces minimal apoptosis, nano-TiO2 treated samples displayed approximately 28% early apoptosis after 24 h of NMs exposure. We further showed that nano-TiO2 mediated cell death is independent of the classical p53-Bax apoptosis pathway. Our findings provided insights into the potential cellular fates of human oral epithelial cells as they interface with industrial grade nano-HA and nano-TiO2.

Preparation of graphene oxide reinforced hydroxyapatite Poly (vinyl alcohol) nanocomposite materials

“…The SEM observation of as-synthesized HA nanoparticles are shown in Figure 2 (A), which indicates that the morphology of the HA was rod like particle with 30-50nm in length and 10-20 nm wide. The size is similar to the size of HA in natural bones [22][23][24]. SEM observation on the HA-GO samples showed that the GO flasks covered with the HA particles to form the uniform mixtures Figure 2 (B).…”

Interaction of hydroxyapatite nanoparticles with endothelial cells: internalization and inhibition of angiogenesis in vitro through the PI3K/Akt pathway

“…The cytotoxic effect of np20 and np80 on HUVECs could be attributed to the induction of oxidative stress by HANPs as well as elevated intracellular calcium concentration due to substantial uptake of HANPs (Figures 3-5). 30,31 To date, the cytotoxicity of HANPs still remains a matter of debate. It has also been reported that HANPs were compatible to mouse bone marrow mesenchymal stem cells.…”

Nanoscience and nanotechnologies for biobased materials, packaging and food applications: New opportunities and concerns

“…Nevertheless, they do undergo the different physical-chemical conditions along the alimentary tract. In the oral cavity, particles already had a high agglomeration tendency (Teubl, Schimpel et al 2015), but 10% were still available in the nanosized range and penetrated the upper and lower buccal epithelium, independently of hydrophilicity (Tay, Fang et al 2014;Teubl, Leitinger et al 2014;Teubl, Schimpel et al 2015). Once introduced directly in the gastric fluid, TiO2 NPs agglomerate anyway (Jones, Morton et al 2015).…”