Development of polycation-immobilized cellulose particles for selective DNA adsorption based its multipoint attachment

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We have focused a method for the selective removal of DNA from various cellular products using columns packed with polycation-immobilized cellulose beads. Polyethyleneimine (PEI), poly-N,N-dimethylaminopropylacrylamide (poly (DAPA)) and poly (ε-lysine) (PεL), all of which have cationic properties, were used as the ligands on the beads. Cellufine-GC15[○!R] and -CPC^[○!R] were used as cellulose matrices. Adsorption of DNA by the beads was determined using a batchwise method or a column method. Each bead type showed high DNA-adsorbing activity at pH 7.0 and ionic strengths of μ= 0.05-0.8. The larger the pore size of the beads, the larger the DNA-adsorbing activity. The DNA- adsorbing capacities per wet-mL of PEI-, poly(DAPA)- and PεL-immobilized Cellufine-CPC with large pore sizes, were 3.7, 3.2 and 1.8 mg, respectively. When a protein, such as bovine serum albumin (BSA) or γ-globulin, was present in solution with the DNA under physiological conditions (pH 7.0,μ= 0.2), the DNA selectivity of the PEI-immobilized Cellufine-CPC columns was unsatisfactory, because both the DNA and the protein were adsorbed onto the column. In contrast, the poly (DAPA) -immobilized Cellufine-CPC column selectively removed DNA from each protein solution contaminated with DNA under similar conditions : the DNA concentration in each treated protein solution was below 10 ng /mL, and high recovery of each protein (>92%) was obtained.