QIAamp Circulating Nucleic Acid Kit

Analysis of tumor-specific extracellular DNA fragments and mRNAs in the blood can enable specific detection of tumor types from a simple blood sample. These circulating nucleic acids are present in serum or plasma usually as short fragments, <1000 bp (DNA) or <1000 nt (RNA). In addition, miRNAs, as small as 21 nt, have the potential to provide biomarkers for certain cancers and disease states.

The QIAamp Circulating Nucleic Acid Kit enables efficient purification of these circulating nucleic acids from human plasma or serum and other cell-free body fluids. Efficient purification with reproducible yields provides a representative population of the circulating nucleic acids in blood (see figure "Reproducible recovery of circulating DNA"). Tube extenders and vacuum processing on the QIAvac 24 Plus enable starting sample volumes of up to 5 ml, and flexible elution volumes between 20 μl and 150 μl allow concentration of nucleic acid species that are present in low concentrations. The kit provides advanced technology of selective binding to a silica-based membrane for improved recovery of fragmented nucleic acids (see figure "Improved recovery of fragmented DNA").

Purification of circulating RNA, without copurification of DNA, is possible with DNA digestion using the RNase-Free DNase Set. A specialized protocol provides highly efficient purification of small RNA, such as miRNAs (see figure "Efficient purification of circulating miRNA"). Methylated DNA can be efficiently purified using the QIAamp Circulating Nucleic Acid Kit. The purified DNA maintains its methylation, allowing bisulfite conversion for analysis of the methylation state (see figure "Efficient recovery of methylated DNA").

The purified and concentrated circulating DNA and RNA is free of proteins, nucleases, and other impurities, and is ready to use in wide range of downstream applications, including:

• PCR and quantitative real-time PCR and RT-PCR
• Biomarker research and validation for blood-based cancer detection
• Viral nucleic acid detection

The QIAamp Circulating Nucleic Acid Kit simplifies isolation of circulating DNA and RNA from plasma or serum. No phenol–chloroform extraction is required. Nucleic acids bind specifically to the QIAamp Mini column, while contaminants pass through. PCR inhibitors, such as divalent cations and proteins, are completely removed in 3 wash steps, leaving pure nucleic acids to be eluted in a buffer provided with the kit. The QIAamp Circulating Nucleic Acid technology yields circulating DNA and RNA from human plasma, serum, or urine.

The QIAamp Circulating Nucleic Acid Kit combines the selective binding properties of silica-based membrane with flexible elution volumes between 20 and 150 μl. Circulating RNA can be purified with DNA digestion using the RNase-Free DNase Set.

The QIAamp Circulating Nucleic Acid procedure includes 4 steps (lyse, bind, wash, and elute) that are carried out using QIAamp Mini columns on a vacuum manifold. The simple procedure is highly suited for simultaneous processing of multiple samples, providing nucleic acids in less than 2 hours per 24 samples. If the QIAamp Circulating Nucleic Acid Kit is used for isolation of viral RNA and DNA, the performance cannot be guaranteed for every virus species and must be validated by the user.

The QIAamp Circulating Nucleic Acid Kit efficiently purifies and concentrates free-circulating DNA, RNA, miRNA, and viral nucleic acids from starting materials that contain low concentrations of mostly fragmented DNA and RNA (typically 1–100 ng/ml circulating DNA in human plasma). Starting sample volumes can be up to 5 ml.

The QIAamp Circulating Nucleic Acid Kit purifies and concentrates nucleic acids from the following sample types:

• Human plasma
• Serum
• Urine