Molecularly imprinted cryogel for L-glutamic acid separation

A molecular recognition based L‐glutamic acid (L‐GLU) imprinted cryogel was prepared for L‐GLU separation via chromatographic applications. The novel functional monomer N‐methacryloyl‐(L)‐glutamic acid‐Fe3+ (MAGA‐Fe3+) was synthesized to be complex with L‐GLU. The L‐GLU imprinted cryogel was prepared by free radical polymerization under semifrozen conditions in the presence of a monomer‐template complex MAGA‐Fe3+‐L‐GLU. The binding mechanism of MAGA‐Fe3+ and L‐GLU was characterized by Fourier transform infrared (FTIR) spectroscopy in detail. FTIR analyses on the synthesized MAGA‐Fe3+‐GLU complex reveals bridging bidentate and monodentate binding modes of Fe3+ in complex with the carboxylate groups of the glutamate residues. The template L‐GLU could be reversibly detached from the cryogel to form the template cavities using a 100 mM solution of HNO3. The amount of adsorbed L‐GLU was detected using the phenyl isothiocyanate method. The L‐GLU adsorption capacity of the cryogel decreased drastically from 11.3 to 6.4 μmol g−1 as the flow rate increased from 0.5 to 4.0 mL min−1. The adsorption onto the L‐GLU imprinted cryogel was highly pH dependent due to electrostatic interaction between the L‐GLU and MAGA‐Fe3+. The PHEMAGA‐Fe3+‐GLU cryogel exhibited high selectivity to the corresponding guest amino acids (i.e., D‐GLU, L‐ASN, L‐GLN, L‐, and D‐ASP). Finally, the L‐GLU imprinted cryogel was recovered and reused many times, with no significant decrease in their adsorption capacities. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 2012