Gold nanoparticle interference study during the isolation, quantification, purity and integrity analysis of RNA

PLoS One. 2014 Dec 3;9(12):e114123. doi: 10.1371/journal.pone.0114123. eCollection 2014.

Abstract

Investigations have been conducted regarding the interference of nanoparticles (NPs) with different toxicological assay systems, but there is a lack of validation when conducting routine tests for nucleic acid isolation, quantification, integrity, and purity analyses. The interference of citrate-capped gold nanoparticles (AuNPs) was investigated herein. The AuNPs were added to either BEAS-2B bronchial human cells for 24 h, the isolated pure RNA, or added during the isolation procedure, and the resultant interaction was assessed. Total RNA that was isolated from untreated BEAS-2B cells was spiked with various concentrations (v/v%) of AuNPs and quantified. A decrease in the absorbance spectrum (220-340 nm) was observed in a concentration-dependent manner. The 260 and 280 nm absorbance ratios that traditionally infer RNA purity were also altered. Electrophoresis was performed to determine RNA integrity, but could not differentiate between AuNP-exposed samples. However, the spiked post-isolation samples did produce differences in spectra (190-220 nm), where shifts were observed at a shorter wavelength. These shifts could be due to alterations to chromophores found in nucleic acids. The co-isolation samples, spiked with 100 µL AuNP during the isolation procedure, displayed a peak shift to a longer wavelength and were similar to the results obtained from a 24 h AuNP treatment, under non-cytotoxic test conditions. Moreover, hyperspectral imaging using CytoViva dark field microscopy did not detect AuNP spectral signatures in the RNA isolated from treated cells. However, despite the lack of AuNPs in the final RNA product, structural changes in RNA could still be observed between 190-220 nm. Consequently, full spectral analyses should replace the traditional ratios based on readings at 230, 260, and 280 nm. These are critical points of analyses, validation, and optimization for RNA-based techniques used to assess AuNPs effects.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line
  • Electrophoresis, Agar Gel
  • Gold / chemistry*
  • Humans
  • Metal Nanoparticles / chemistry*
  • Microscopy
  • RNA / analysis*
  • RNA / isolation & purification
  • Spectrophotometry, Ultraviolet
  • Time Factors

Substances

  • RNA
  • Gold

Grants and funding

MG received funding for this work from the South African Department of Science and Technology (http://www.dst.gov.za/) and the National Institute for Occupational Health (http://www.nioh.ac.za/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.