Begum Elmas

Poly(hydroxyethylmethacrylate‐N‐methacryloyl‐(L)‐histidine‐methyl‐ester) Based Metal‐Chelate Affinity Adsorbent for Separation of Lysozyme

Abstract Comonomer and/or metal‐chelating ligand N‐methacryloyl‐(L)‐histidine‐methylester (MAH) was synthesized by using methacryloyl chloride and L‐histidine methyl ester. Spherical beads with an average diameter of 75–125 µm were produced by suspension polymerization of 2‐hydroxyethyl methacrylate (HEMA) and MAH carried out in an aqueous dispersion medium. Poly(HEMA‐MAH) beads had a specific surface area of 18.3 m2/g. Elemental analysis of MAH for nitrogen was estimated as 895 µmol/g of polymer. Then the beads were loaded with different metal ions (i.e. Zn2+, Cu2+, Ni2+) to form the metal chelate. The effect of pH, concentration of lysozyme, and metal type on the adsorption of lysozyme to the metal‐chelated beads was examined in a batch reactor. Purification of lysozyme from egg‐white was also investigated. Maximum lysozyme adsorption capacity of poly(HEMA‐MAH) beads was found to be 8.7 mg/g at pH 7.0 in phosphate buffer. Lysozyme adsorption capacity of Zn2+, Cu2+, and Ni2+‐chelated beads was higher than that of non‐chelated beads. The maximum capacities of Ni2+, Zn2+, or Cu2+‐chelated beads were 11.5, 12.6, and 37.1 mg/g, respectively. A significant amount of the adsorbed lysozyme (up to 97%) was eluted in 1 h in the elution medium containing 25 mM EDTA at pH 4.9. Repeated adsorption‐desorption process showed that this novel metal chelated beads are suitable for lysozyme adsorption. Purification of lysozyme was monitored by determining the lysozyme activity using Micrococcus lysodeikticus as substrate. The purity of the desorbed lysozyme was about 80% with recovery about 75%.

DNA-responsive uniform latex particles based on p-chloromethylstyrene

In this study, DNA binding properties of poly(ethylenimine) (PEI)-attached uniform poly(p-chloromethystyrene) (PCMS) particles were investigated. Spherical PCMS latex particles with an average size of 1.75 μm were obtained by the dispersion polymerization of p-chloromethylstyrene (CMS). PEI was covalently attached onto the PCMS particles via a direct chemical reaction between amine and chloromethyl groups, with the equilibrium binding capacities up to 41 mg PEI/g PCMS. In aqueous media, PEI attached-uniform PCMS particles showed an irreversible aggregation behaviour in the presence of DNA. To predict unknown DNA concentration, the aggregation response of these particles to the presence of DNA was quantified by spectrophotometry. Plain PCMS and PEI attacheduniform PCMS particles were also utilized as sorbents in DNA adsorption experiments conducted at +4°C in a phosphate buffer medium at pH 7.4. DNA immobilization capacities up to 45 mg DNA/g PCMS could be achieved with the PEI attached particles.

Uniform Particles for the Reversed-Phase Separation of Proteins with High-Resolution and High-Column Efficiency

Abstract A low‐sized, uniform and polymer‐based high‐performance liquid chromatography (HPLC) packing material capable of making reversed‐phase separation of proteins with high resolution and with high column efficiency was developed. By a multistage‐swelling and polymerization protocol, 5 µm‐uniform‐porous poly(styrene‐co‐divinylbenzene) particles with relatively larger pores particularly suitable for protein separation were synthesized by starting from a low‐sized seed latex with high average molecular weight and by using a diluent phase comprised of dibutylphthalate and toluene. By the use of synthesized beads as packing material in HPLC, high‐resolution liquid chromatograms were obtained in the gradient separation of selected proteins (i.e., ribonuclease‐A, lysozyme, cytochrome C, and albumin). In the chromatographic runs, the flow rate of the mobile phase was increased fourfold by preserving the resolution power of the column material under gradient conditions. The theoretical plate numbers (TPN) up to 12.500 plates/m were observed by using cytochrome C as the analyte. TPN values determined by the proteins were significantly higher relative to the similar uniform packing materials larger in size (i.e., 7.5–10 µm) obtained by different polymerization methods.