Preparations and Applications of Polyethyleneimine-Immobilized Cellulose Fibers for Endotoxin Removal

Abstract

ABSTRACT:Through the immobilization of polyethyleneimine (PEI) onto cellulose fibers, novel fibrous adsorbents (Cell-PEI fibers) for the removal of endotoxins were prepared. Anionexchange capacity and pore size (molecular mass exclusion, Mlim) of the Cell-PEI fibers were readily adjusted by changing the ratio of polyethyleneimine and sodium carbonate to cellulose during suspension. The adsorption of endotoxin by the fibers increased with anion-exchange capacity of the fibers, and decreased with increase in the ionic strength of the buffer. The Cell-PEI fibers (anion-exchange capacity 1.1 to 3.0meqg-1 ) showed high endotoxin-adsorbing activity at pH 5 to 9 and ionic strength ofµ= 0.05 to 0.2. The adsorbing activity for acidic protein such as bovine serum albumin (BSA) increased with Mlim and the anion-exchange capacity of the fibers, but decreased with increase in the ionic strength of the buffer. The Cell-PEI fibers (Mlim: 2000, anion-exchange capacity: 1. I meq g-1 ) selectively reduced endotoxins in various protein solutions containing endotoxins at pH 7 andµ= 0.05. The residual concentration of endotoxins in the protein solutions decreased to less than 0.1 ng m1-1 , and recovery rate of the protein was over 98% in all cases. KEY WORDSEndotoxin / Pyrogen / Lipopolysaccharide / Selective Removal / Cellulose Fiber / Polyethyleneimine / Bovine Serum Albumin / Endotoxins, constituents of the cell wall of gram-negative bacteria, are pyrogenic lipopolysaccharides (LPS). Their potent biological activity causes pyrogenic and shock reactions in mammals on intravenous injection even in nanogram amounts. 1 • 2 A number of attempts have been made to remove endotoxins from cell products used as drugs. 3 • 4 To remove them from protein solutions, adsorption has proven to be the most effective. Histidine-immobilized cellulose 5 • 6 and polymyxine-immobilized Sepharose 7 are presently sold as endotoxin adsorbents. However, these adsorbents cannot remove endotoxins selectively, since their adsorbing capacity is high for both endotoxins and acidic proteins such as bovine serum albumin (BSA) at low ionic strength ofµ= 0.05 and neutral pH. When the ionic strength of the buffer increased beyondµ= 0.2, the adsorption of BSA decreased, but the adsorption of endotoxins was slight. 6 t To whom correspondence should be addressed.Therefore, we attempted to develop endotoxin adsorbents capable of retaining high endotoxin-removing activity at a wide ionic strength range. We previously reported that aminated poly(y-methyl L-glutamate) (PMLG) spheres, 8 • 9 which have diaminoethane as a ligand, selectively remove endotoxins from various protein solutions at the high ionic strength of µ=0.2 to 0.8. However, the adsorption of an acidic protein can also be done at a low ionic strength ofµ= 0.05. 9 831 s. MORIMOTO et al.

Preparation and performance of cellulose acetate/polyethyleneimine blend microfiltration membranes and their applications

“…Polyethyleneimine (PEI) is a branched chain polymer with a lot of amine groups and has extensively been used to modify membrane surface [19], effectively complex heavy metal ions [20][21][22][23] and selectively adsorb endotoxins [24] from protein solutions. By different methods of chemical modification, PEI can be immobilized on the surfaces of basic membranes and used as ligands [25][26][27][28] or to supply further coupling sites for immobilization of different ligands [29].…”

Influence of the polyethyleneimine grafting on the adsorption capacity of chitosan beads for Reactive Black 5 from aqueous solutions

“…In fact, the adsorption capacity of PEI-CB was found to be higher than that of PEI-CSB at all pH levels tested in this study and the effective pH range of PEI-CB for adsorption of RB5 was higher than that of PEI-CSB. The pK a (10.5) of PEI is higher than that of CS (6.5), and the higher the pK a value of the ligand (PEI) grafted onto the adsorbent, the wider is the effective pH range for anionic dye adsorption [24]. As shown in Table 1, PEI amount in PEI-CB was much more than that in PEI-CSB and so, the adsorption capacity of PEI-CB showed less sensitivity to pH change of dye solution than that of PEI-CSB because of the higher amount of PEI grafted in PEI-CB than that in PEI-CSB.…”

Chromatographic Removal of DNA from Protein Solutions by Cationic Polymer Beads

“…Morimoto, et al [42] has already developed polyethylene-immobilized cellulose fibers for adsorption of LPS. Morimoto, et al [42] has already developed polyethylene-immobilized cellulose fibers for adsorption of LPS.…”

“…The effect of pH on DNA adsorption by various cationic beads was examined using a batchwise method [13,42]. As shown in Fig.…”