Dye affinity cryogels for plasmid DNA purification

The aim of this study is to prepare megaporous dye-affinity cryogel discs for the purification of plasmid DNA (pDNA) from bacterial lysate. Poly(hydroxyethyl methacrylate) [PHEMA] cryogel discs were produced by free radical polymerization initiated by N,N,N′,N′-tetramethylene diamine (TEMED) and ammonium persulfate (APS) redox pair in an ice bath. Cibacron Blue F3GA was used as an affinity ligand (loading amount: 68.9 μmol/g polymer). The amount of pDNA adsorbed onto the PHEMA-Cibacron Blue F3GA cryogel discs first increased and then reached a plateau value (i.e., 32.5 mg/g cryogel) at 3.0 mg/mL pDNA concentration. Compared with the PHEMA cryogel (0.11 mg/g cryogel), the pDNA adsorption capacity of the PHEMA-Cibacron Blue F3GA cryogel (32.4 mg/g polymer) was improved significantly due to the Cibacron Blue 3GA immobilization onto the polymeric matrix. pDNA adsorption amount decreased from 11.7 mg/g to 1.1 mg/g with the increasing of NaCl concentration. The maximum pDNA adsorption was achieved at 4 °C. The overall recovery of pDNA was calculated as 90%. The PHEMA-Cibacron Blue F3GA cryogel discs could be used five times without decreasing the pDNA adsorption capacity significantly. The results show that the PHEMA-Cibacron Blue F3GA cryogel discs promise high selectivity for pDNA.