Preparation of cellulose beads grafted with cationic polymer chains through ATRT for separation of DNA — ASN Events
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  3. Preparation of cellulose beads grafted with cationic polymer chains through ATRT for separation of DNA

Preparation of cellulose beads grafted with cationic polymer chains through ATRT for separation of DNA (#284)

Masayo Sakata 1 , Eri Ikegami 1 , Yusuke Goto 1
  1. Kumamoto University, Chuo-ku, Kumamoto, Japan

   This report describes the synthesis of the DNA adsorbent by surface initiated atom transfer radical polymerization (SI-ATRP), and then provide a method for the purification of DNA from a protein solution using the adsorbent beads-packed columns.

   To synthesize the DNA adsorbent, at first, ethylenediamine was grafted onto chloromethyloxirane-activated cellulose beads. Then 2-bromo-2-methyl-propionyl bromide (BMPB) was introduced into the aminated beads as initiating sites for SI-ATRP.Cu(I)Br/phenanthrolin catalyst-ligand system was used for polymerization of N,N-dimethylaminopropylacryl-amide (DAPA) in water at 100°C. The content of initiating sites and the degree of polymerization (amino-exchange capacity; AEC) were adjusted by changing BMPB content of beads and polymerization time, respectively. The resulting various polyDAPA grafted cellulose beads, which had diameters of 44–105 μm and matrix’s pore-sizes of 1×103–1×106 as molecular mass exclusions (Mlim), were used as adsorbents.

   The separation of DNA (salmon spermary, Mw 3×105) and bovine serum albumin (BSA) was investigated by a frontal column method with various polyDAPA grafted cellulose beads packed columns (DAPA column).  The DAPA-LL columm, which have the ligand of low density (BMPB content: 0.15 m-mol/g) and the long chain length (DAPA-polymerization degree: 30), showed the highest DNA-selectivity at pH 7.0 and ionic strength (μ) 0.2: DNA adsorption was 99 % (residual concentration <10 ng/mL) and BSA recovery was 90%. However, no DNA was eluted when the DNA-saturated column was then treated with the salt gradient concentration. We assume that the remaining DNA, which was not eluted, was strongly adsorbed onto the their polyDAPA chain by hydrophobic binding and multipoint attachments. In comparison, the DAPA-HS column, which have the ligand of high density (BMPB content: 0.36 m-mol/g) and the short chain length (DAPA-polymerization degree: 4-9), showed the highest DNA-recovery (elution rate 63%) under a salt gradient condition (0.2-2.0 M). The results indicate that the DAPA-HS beads also allow specific purification of DNA from a protein-containing solution.