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. 2017 Sep 21;8(50):87980–87996. doi: 10.18632/oncotarget.21256

Figure 1. Optimization of circulating free DNA (cfDNA) extraction and quantification of cfDNA in the samples.

Figure 1

(A) Reproducibility of cfDNA extraction using the QIAamp Circulating Acid Kit (Qiagen, Cat No 55114, Valencia, CA, USA) on two independent cfDNA samples extracted from 1 mL (Ai) and 3 mL (Aii) of plasma from NSCLC patients. After extraction, cfDNA was quantified by Qubit dsDNA HS Assay Kit (Life Technologies, Q32854, Carlsbad, CA, USA) according to the manufacturer's instructions. (B) Correlation between the initial volume of plasma 1 mL versus 3 mL (Bi) or 3 mL versus 5 mL (Bii) and the quantity of cfDNA extracted (in ng/μL). (Ci) Fragment size visualization of cfDNA (in bp) from a concentrated (left) and a less concentrated (right) sample obtained using the Bioanalyzer (Agilent Technologies, Santa Clara, CA, USA) (Cii), and average size distribution (10 bp increments) of cfDNA fragments in 77 plasma samples. (D) Correlation between cfDNA concentration measured using the Qubit method and the number of amplifiable copies in the corresponding plasma samples determined using the Quantifiler Kit.