Allelic discrimination between circulating tumor DNA fragments enabled by a multiplex-qPCR assay containing DNA-enriched magnetic ionic liquids

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2020-05-06
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Emaus, Miranda
Anderson, Jared
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Ames National Laboratory

Ames National Laboratory is a government-owned, contractor-operated national laboratory of the U.S. Department of Energy (DOE), operated by and located on the campus of Iowa State University in Ames, Iowa.

For more than 70 years, the Ames National Laboratory has successfully partnered with Iowa State University, and is unique among the 17 DOE laboratories in that it is physically located on the campus of a major research university. Many of the scientists and administrators at the Laboratory also hold faculty positions at the University and the Laboratory has access to both undergraduate and graduate student talent.

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Chemistry

The Department of Chemistry seeks to provide students with a foundation in the fundamentals and application of chemical theories and processes of the lab. Thus prepared they me pursue careers as teachers, industry supervisors, or research chemists in a variety of domains (governmental, academic, etc).

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The Department of Chemistry was founded in 1880.

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1880-present

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Ames National LaboratoryChemistry
Abstract

Multiplex amplification of DNA can be highly valuable in circulating tumor DNA (ctDNA) analysis due to the sheer number of potential mutations. However, commercial ctDNA extraction methods struggle to preconcentrate low concentrations of DNA and require multiple sample handling steps. Recently, magnetic ionic liquids (MILs) have been used to extract DNA and were integrated with a quantitative polymerase chain reaction (qPCR). However, in previous studies, DNA could not be preconcentrated from plasma and only one fragment could be amplified per reaction. In this study, MILs were utilized as DNA extraction solvents and directly integrated into a multiplex-qPCR buffer to simultaneously amplify wild-type KRAS, G12S KRAS, and wild-type BRAF, three clinically-relevant genes whose mutation status can affect the success of anti-EGFR therapy. DNA was desorbed from the MIL solvent during a multiplex-PCR without having a significant effect on the amplification efficiency, and allelic discrimination of single-nucleotide polymorphisms could still be achieved. Enrichment factors over 35 for all three sequences were achieved from Tris buffer using the [N8,8,8,Bz+][Ni(hfacac)3-]) and [P6,6,6,14+][Ni(Phtfacac)3-] MILs. DNA could still be preconcentrated from 2-fold diluted human plasma using the [N8,8,8,Bz+][Ni(hfacac)3-] MIL. Extractions from undiluted plasma were reproducible with the [P6,6,6,14+][Ni(Phtfacac)3-] MIL although DNA was not preconcentrated with enrichment factors around 0.6 for all three fragments. Compared to commercial DNA extraction methods (i.e., silica-based spin columns and magnetic beads), the MIL-based extraction achieved higher enrichment factors in Tris buffer and plasma. The ability of the MIL-based dispersive liquid-liquid microextraction (DLLME) direct-multiplex-qPCR method to simultaneously achieve high enrichment factors of multiple DNA fragments from human plasma is highly promising in the field of ctDNA detection.

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This is a manuscript of an article posted as Emaus, Miranda N., and Jared L. Anderson. "Allelic discrimination between circulating tumor DNA fragments enabled by a multiplex-qPCR assay containing DNA-enriched magnetic ionic liquids." Analytica Chimica Acta (2020). DOI: 10.1016/j.aca.2020.04.078. Posted with permission.

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Wed Jan 01 00:00:00 UTC 2020
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