Jil

FIG. 10 Possible interaction mechanisms between immobilized PEI and DNA. (Reprinted with permission from Ref. 23, Copyright © 2000, Elsevier Science.)

FIG. 11 Variation of absorbance for the PEI-attached PCMS latex-DNA mixtures and plain PCMS latex-DNA mixtures with the DNA concentration. (Reprinted with permission from Ref. 24, Copyright © 2001, VSP International Science Publishers.)

of N-3-dimethylaminopropylmethacrylamide (DMAPM) [25]. The variation of equilibrium DNA adsorption capacity with the initial DNA concentration at pH 7.4 and 25°C is shown in Fig. 13. As seen in the figure, the equilibrium DNA adsorption capacities up to 55 mg DNA/g dry beads could be achieved via the ionic interaction between the dimethylaminopropyl groups of the support material and phosphate bonds of DNA [25]. In the desorption experiments, yields lower than 5% (w/w) were obtained in Tris-HCl buffer solution including 1 M

ch2-ch2-nh2

CHJ-CHJ-NHJ

PEI attached-PCMS particles

LEGENDS

^^ Bases in DNA D' Deoxyribose units

™ Phosphate bonds

Hydrogen bonds

- PEI chain

CHJ-CHJ-NHJ

ch2-ch2-nh2

FIG. 13 Variation of equilibrium DNA adsorption capacity of uniform poly(DMAPM) gel beads with the initial DNA concentration. (Reprinted with permission from Ref. 25, Copyright © 2000, John Wiley and Sons, Inc.)

NaCl [25]. These results indicated that the ionic interaction was sufficiently strong to obtain a stable DNA binding on the surface of the gel beads [25].

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