Thursday, June 9, 2016

ALD functionalization with ZnO generates CNTs that possess increased risk for human exposure

Here is a study on the risks of novel nano materials and in this parrticular case ZnO ALD coated multi walled carbon annotuber (MWCNTs). The study concludes that  "Pulmonary exposure to ZnO-coated MWCNTs produces a systemic acute phase response that involves the release of Zn+2, lung epithelial growth arrest, and increased IL-6. ALD functionalization with ZnO generates MWCNTs that possess increased risk for human exposure." So basically be very careful in the lab and use gloves, lab coat, safety glaces and and a mask when handling your new smart nano materials since there is no way you can tell if what you have synthesised is a potent risk for you and your surroundings. The study is OPEN ACCESS and free to download as below.

Atomic layer deposition coating of carbon nanotubes with zinc oxide causes acute phase immune responses in human monocytes in vitro and in mice after pulmonary exposure


Erinn C. Dandley, Alexia J. Taylor, Katherine S. Duke, Mark D. Ihrie, Kelly A. Shipkowski, Gregory N. Parsons and James C. Bonner
Particle and Fibre Toxicology 201613:29, DOI: 10.1186/s12989-016-0141-9 [OPEN ACCESS]

 
Background

Atomic layer deposition (ALD) is a method for applying conformal nanoscale coatings on three-dimensional structures. We hypothesized that surface functionalization of multi-walled carbon nanotubes (MWCNTs) with polycrystalline ZnO by ALD would alter pro-inflammatory cytokine expression by human monocytes in vitro and modulate the lung and systemic immune response following oropharyngeal aspiration in mice.
 
Methods

Pristine (U-MWCNTs) were coated with alternating doses of diethyl zinc and water over increasing ALD cycles (10 to 100 ALD cycles) to yield conformal ZnO-coated MWCNTs (Z-MWCNTs). Human THP-1 monocytic cells were exposed to U-MWCNTs or Z-MWCNTs in vitro and cytokine mRNAs measured by Taqman real-time RT-PCR. Male C57BL6 mice were exposed to U- or Z-MWCNTs by oropharyngeal aspiration (OPA) and lung inflammation evaluated at one day post-exposure by histopathology, cytokine expression and differential counting of cells in bronchoalveolar lavage fluid (BALF) cells. Lung fibrosis was evaluated at 28 days. Cytokine mRNAs (IL-6, IL-1β, CXCL10, TNF-α) in lung, heart, spleen, and liver were quantified at one and 28 days. DNA synthesis in lung tissue was measured by bromodeoxyuridine (BrdU) uptake.

Results

ALD resulted in a conformal coating of MWCNTs with ZnO that increased proportionally to the number of coating cycles. Z-MWCNTs released Zn+2 ions in media and increased IL-6, IL-1β, CXCL10, and TNF-α mRNAs in THP-1 cells in vitro. Mice exposed to Z-MWCNTs by OPA had exaggerated lung inflammation and a 3-fold increase in monocytes and neutrophils in BALF compared to U-MWCNTs. Z-MWCNTs, but not U-MWCNTs, induced IL-6 and CXCL10 mRNA and protein in the lungs of mice and increased IL-6 mRNA in heart and liver. U-MWCNTs but not Z-MWCNTs stimulated airway epithelial DNA synthesis in vivo. Lung fibrosis at 28 days was not significantly different between mice treated with U-MWCNT or Z-MWCNT.

Conclusions

Pulmonary exposure to ZnO-coated MWCNTs produces a systemic acute phase response that involves the release of Zn+2, lung epithelial growth arrest, and increased IL-6. ALD functionalization with ZnO generates MWCNTs that possess increased risk for human exposure.