Selective removal of DNA from protein solution with copolymer particles derived from N,N-dimethylaminopropylacrylamide

To remove nucleic acids from cellular products as drugs, cross-linked N,N-dimethylaminopropylacrylamide (DMP) particles with cationic functional groups were prepared. The particle’s hydrophobicity and its anion-exchange capacity were easily adjusted by changing the cross-linking agent and the DMP ratio in the cross-linking, respectively. When divinylbenzene (DVB) was used as a cross-linking agent and the DMP ratio (in the cross-linking) was adjusted to 90 mol%, the particles (DMP–DVB, 90:10) showed the highest adsorbing activity of DNA (salmon spermary). Its adsorption capacity was 54 mg/ml adsorbent. On the other hand, the adsorption of bovine serum albumin (BSA) to the DMP–DVB extremely increased with increase in the adsorbent’s pore size (molecular mass exclusions; Mlim) from 2×103 to 1×104, but decreased with increase in the buffer’s ionic strength (μ) to 0.2 or stronger. As a result, when the DMP–DVB (80:20) with Mlim 2×103 was used as adsorbent by a column method at pH, 7.2 and μ=0.17, it only selectively removed DNA from a BSA solution, including 1000 μg/ml of BSA and 10 μg/ml of DNA. The adsorbent decreased the concentration of DNA in the BSA solution to <10 ng/ml, and the recovery rate of BSA was more 98%.