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.
Highlights
Plasmonic engineered nanoparticles (NPs) are popular in consumer- and medical-based industries due to their unique surface characteristics
This study was initiated in order to determine if any AuNP interference occurred during the isolation, quantification and integrity analyses of RNA obtained from the BEAS-2B human cell line
The RNA isolated from the 24 h AuNP-treated samples was considered to be suitable for RNA-based techniques when using the traditional methods, additional screening identified changes that are associated with structural alterations of functional groups
Summary
Plasmonic engineered nanoparticles (NPs) are popular in consumer- and medical-based industries due to their unique surface characteristics. Identifying the toxicity of NPs is, critical given increased exposure and it has become increasingly important to validate assay parameters for techniques used to determine cyto- and genotoxicity. The toxicity of NPs is often determined using conventional colorimetric and optical high-throughput toxicity systems that rely on absorbance, luminescence or fluorescence signals. NPs themselves may interfere with these assay mechanisms [1], producing inaccurate results. There is a lack of assay validation when conducting research with NPs, especially with regard to routine tests for nucleic acid quantification and purity analyses. Toxicity results should be interpreted with caution when using conventional systems, where systems that rely on dyes or optical devices should be avoided. Methods based on label-free technologies should be implemented [2]
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