Eylem Turan

Construction of myoglobin imprinted polymer films by grafting from silicon surface

Molecularly imprinted polymer (MIP) films on silicon wafers were prepared by surface-initiated atom transfer polymerization (ATRP). 2-hydroxyethyl methacrylate and ethylene glycol dimethacrylate were used as the functional monomer and the cross-linking agent, respectively. Myoglobin (Mb) was selected as the template molecule to form the MIP films. Various characterization techniques including ellipsometry, contact-angle goniometer, atomic force microscopy, grazing angle-Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, were used to characterize the films. Ellipsometry was also used to quantify and compare the binding capacity of the MIP and nonimprinted polymer (NIP) films. The MIP films exhibited higher rebinding capacity than the NIP films at all solution concentrations of Mb. A selectivity coefficient of 3.15 was achieved for the MIP films prepared against the Mb template molecule.

Hemoglobin recognition of molecularly imprinted hydrogels prepared at different pHs.

The hemoglobin-imprinted hydrogels were fabricated by using N-t-butylacrylamide (TBA) acrylamide (AAm) and itaconic acid (IA) monomers and hemoglobin (Hb, MW 65 kDa) imprinted molecule in pH buffer solutions (pH 4.0, 6.8 and 8.0). The nonimprinted hydrogels were also prepared at same conditions without Hb imprinting molecule. The effects of pH, initial concentration and adsorption time over the Hb adsorption capacity of both imprinted and nonimprinted hydrogels were analyzed and found to be strongly dependent on the preparation pH (pH(prep)). The maximum Hb adsorption for the imprinted hydrogel prepared at pH 4.0 was found to be 12.4 mg protein g(-1) dry gel in pH 4.0 buffer solution. This behavior was attributed to the formation of more accessible adsorption sites (imprints) because of the non-covalent interactions between the template and network during formation in pH 4.0 buffer solution which is below of the isoelectric point (pI 6.8) of Hb. Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherm. Langmuir analysis showed that an equal class of adsorption was formed in the hydrogels. Moreover, batch adsorption equilibrium and selectivity studies were also performed by using two reference molecules as fibrinogen (Fb, MW 340 kDa) and myoglobin (Mb, MW 17 kDa). The imprinted hydrogels have 1.5-2.2 times higher adsorption capacity for Hb than the nonimprinted hydrogels prepared at the same pHs, and also have 2.0-3.1 times higher selectivity for the imprinted molecule.

Dependence of Protein Recognition of Temperature-Sensitive Imprinted Hydrogels on Preparation Temperature

Temperature-sensitive imprinted and non-imprinted hydrogels composed of N-isopropylacrylamide (NIPA) and 2-acrylamido-2-methyl-propanosulfonic acid (AMPS) have been prepared by free-radical crosslinking copolymerization in aqueous solution at three different temperatures: 10 degrees C (below the lower critical solution temperature, LCST), 33 degrees C (at the LCST), and 40 degrees C (above the LCST). Myoglobin (Mb, MW 17 kDa) is used as the template biomolecule. The effects of the initial concentration and adsorption time over the Mb adsorption capacity of the hydrogels have been analyzed and found to be strongly dependent on the preparation temperature (T(prep)). The maximum Mb adsorption for the imprinted hydrogel prepared at 10 degrees C is 97.40 +/- 2.35 mg Mb x g(-1) dry gel in 0.32 mg x mL(-1) Mb solution at 22 degrees C. Moreover, batch adsorption equilibrium and selectivity studies have been performed using a reference molecule, hemoglobin (Hb, MW 65 kDa). The imprinted hydrogels have a 2.8-3.3 times higher adsorption capacity for Mb than the non-imprinted hydrogels prepared at the same T(prep)s, and also have a 1.8-2.7 times higher selectivity for the imprinted molecule.