Electronic platform for real-time multi-parametric analysis of cellular behavior post-exposure to single-walled carbon nanotubes

Our plain-English summary of Electronic platform for real-time multi-parametric analysis of cellular behavior post-exposure to single-walled carbon nanotubes, by R. Eldawud, A. Wagner, C. Dong, et al (Biosensors & Bioelectronics, 2015).

The study

• Authors: R. Eldawud, A. Wagner, C. Dong, Y. Rojansakul, C. Zoica Dinu
• Journal: Biosensors & Bioelectronics
• Published: 2015;71:269-277
• Cited by: 7 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Single-walled carbon nanotubes (SWCNTs) implementation in a variety of biomedical applications from bioimaging, to controlled drug delivery and cellular-directed alignment for muscle myofiber fabrication, has raised awareness of their potential toxicity. Nanotubes structural aspects which resemble asbestos, as well as their ability to induce cyto and genotoxicity upon interaction with biological systems by generating reactive oxygen species or inducing membrane damage, just to name a few, have led to focused efforts aimed to assess associated risks prior their user implementation. In this study, we employed a non-invasive and real-time electric cell impedance sensing (ECIS) platform to monitor behavior of lung epithelial cells upon exposure to a library of SWCNTs with user-defined physico-chemical properties. Using the natural sensitivity of the cells, we evaluated SWCNT-induced cellular changes in relation to cell attachment, cell-cell interactions and cell viability respectively. Our methods have the potential to lead to the development of standardized assays for risk assessment of other nanomaterials as well as risk differentiation based on the nanomaterials surface chemistry, purity and agglomeration state.

Copyright © 2015 Elsevier B.V. All rights reserved.

In plain English

This laboratory study tested single-walled carbon nanotubes, not asbestos. Asbestos is mentioned only because the nanotubes' structure resembles it. The authors compared untreated (pristine) commercial nanotubes with nanotubes treated in strong acid for 3 or 6 hours. The acid treatment shortened the nanotubes, changed their surface chemistry and reduced metal impurities. Immortalized human lung epithelial cells (BEAS-2B) grown on gold electrodes were exposed to three doses of each type. Their electrical resistance was tracked continuously for 48 hours to measure cell attachment. Compared with unexposed cells, attachment fell most with 6-hour treated nanotubes (60%, 68% and 72% at the low, middle and high dose). It fell less with 3-hour treated nanotubes (29%, 45%, 57%) and least with pristine nanotubes (about 10%). Cells exposed to 6-hour treated nanotubes partly recovered their attachment by 48 hours. Pristine nanotubes caused the largest fall in live cells: about 30% at 48 hours at the two higher doses. The authors concluded that cell responses depended on time, dose and the nanotubes' length, surface chemistry, purity and clumping. They also concluded that the method could help standardize nanomaterial risk testing.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: In vitro laboratory experiment on a human lung cell line, using electric cell impedance sensing (cells grown on gold electrodes) plus apoptosis and live-cell counts
• Who was studied: Immortalized human lung epithelial cells (BEAS-2B) from a commercial cell collection. ECIS experiments had at least 6 replicates per sample. Apoptosis scoring used about 1000 nuclei from ten random fields per sample.
• Exposure: Single-walled carbon nanotubes in three forms: pristine (commercial, from Unidym Inc.) and acid treated for 3 h or 6 h. Each was given at three doses, printed in the text as 100, 50 and 25 mg/ml, for up to 48 h. No asbestos fibers were tested.
• Main results:
  • Acid treatment changed the oxygen and carbon content of the nanotubes and reduced metal impurities.
  • Average nanotube length was 844 plus or minus 162 nm for pristine nanotubes. It fell by 22% (to 656 plus or minus 207 nm) after 3 h of acid treatment and by 39% (to 517 plus or minus 208 nm) after 6 h.
  • Electrical resistance of cells exposed to pristine nanotubes dropped significantly below that of control cells, with no significant differences between doses.
  • Cells exposed to 6 h treated nanotubes had the largest reduction in the attachment (alpha) measure: 60%, 68% and 72% at 25, 50 and 100 (as printed) doses.
  • Cells exposed to 3 h treated nanotubes had 29%, 45% and 57% reductions in the attachment measure at the 25, 50 and 100 doses.
  • Cells exposed to pristine nanotubes had the smallest reduction in attachment, about 10% below control cells, with no significant dose differences.
  • At 48 h, cells exposed to 6 h treated nanotubes showed an average increase of about 38% in their attachment measure compared with 24 h.
  • Percentage of apoptotic (dying) cells:
  • Percentage of apoptotic cells for treated nanotubes: about 5% (24 h) and 11% (48 h) with 3 h treated nanotubes; about 7% (24 h) and 13% (48 h) with 6 h treated nanotubes.
  • At the 100 and 50 doses, live cells fell compared with controls. The initial drops were about 16% (pristine), 14% (3 h treated) and 10% (6 h treated). By 48 h these drops had grown to 30%, 22% and 18%.
  • At the 25 dose, there was no significant reduction in live cells at 24 h.
  • At the 25 dose at 48 h, live cells fell by about 15% (pristine), 12% (3 h treated) and 9% (6 h treated) compared with controls.
• The authors' conclusion: The authors concluded that exposure led to time- and dose-dependent changes in cell behavior, adhesion and viability. They found differences according to nanotube length, surface chemistry, purity and agglomeration state, and said this helps extend electric sensing platforms toward standardized nanomaterial risk evaluation.

Topics

Medical terms in this study, explained in our Lexicon: Genotoxicity, Reactive Oxygen Species (ROS).

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