Protein adsorption to (3-acrylamido propyl) trimethyl ammonium chloride-grafted Sepharose gel: Charge density reduction via copolymerizing with electroneutral monomer drastically increases uptake rate

A strong anion exchanger of poly(glycidyl methacrylate-divinylbenzene) substrate functionalized with cationic quaternary ammonium monomer

A strong anion exchanger applied for ion chromatography is described by grafting methacrylamido propyl trimethyl ammonium chloride onto hydrolyzed poly(glycidyl methacrylate-divinylbenzene) substrate. The anion exchanger has been in detail characterized and the final capacity of the anion exchanger can be readily manipulated by different monomer amounts. It exhibited obvious temperature-sensitive property and large tolerance to the samples with high ionic strength. The obtained anion exchanger demonstrated effective separation ability towards the common seven inorganic anions within 12 min and high separation efficiency, e.g. 58,000 /m of theoretical plate count for chloride. This article is protected by copyright. All rights reserved.

Research Progress on Typical Quaternary Ammonium Salt Polymers

Quaternary ammonium salt polymers, a kind of polyelectrolyte with a quaternary ammonium group, are widely used in traditional and emerging industries due to their good water-solubility, adjustable cationicity and molecular weight, high efficiency and nontoxicity. In this paper, firstly, the properties and several synthesis methods of typical quaternary ammonium salt monomers were introduced. Secondly, the research progress on the synthesis of polymers was summarized from the perspective of obtaining products with high molecular weight, narrow molecular weight distribution and high monomer conversion, and special functional polymers. Thirdly, the relationships between the structures and properties of the polymer were analyzed from the perspectives of molecular weight, charge density, structural stability, and microstructural regulation of the polymer chain unit. Fourthly, typical examples of quaternary ammonium salt polymers in the application fields of water treatment, daily chemicals, petroleum exploitation, papermaking, and textile printing and dyeing were listed. Finally, constructive suggestions were put forward on developing quaternary ammonium salt polymers with high molecular weights, strengthening the research on the relationships between the structures and their properties and pinpointing relevant application fields.

Recent advances in protein chromatography with polymer-grafted media

The strategy of using polymer-grafted media is effective to create protein chromatography of high capacity and uptake rate, giving rise to an excellent performance in high-throughput protein separation due to its high dynamic binding capacity. Taking the scientific development and technological innovation of protein chromatography as the objective, this review is devoted to an overview of polymer-grafted media reported in the last five years, including their fabrication routes, protein adsorption and chromatography, mechanisms behind the adsorption behaviors, limitations of polymer-grafted media and chromatographic operation strategies. Particular emphasis is placed on the elaboration and discussion on the behaviors of ion-exchange chromatography (IEC) with polymer-grafted media because IEC is the most suitable chromatographic mode for this kind of media. Recent advances in both the theoretical and experimental investigations on polymer-grafted media are discussed by focusing on their implications to the rational design of novel chromatographic media and mobile phase conditions for the development of high-performance protein chromatography. It is concluded that polymer-grafted media are suitable for development of IEC and mixed-mode chromatography with charged and low hydrophobic ligands, but not for hydrophobic interaction chromatography with high hydrophobic ligands and affinity chromatography with ligands that have single binding site on the protein.

Protein adsorption to poly(2-aminoethyl methacrylate)-grafted Sepharose gel: Effects of chain length and charge density

Grafting functional polymer chains onto porous resins has been found to drastically increase both adsorption capacity and uptake rate in protein chromatography. In this work, 2-aminoethyl methacrylate (AEM) was used for grafting onto Sepharose FF gel, and six anion-exchangers of different polyAEM (pAEM) chain lengths (ionic capacities, ICs), FF-pAEM, were obtained for protein adsorption and chromatography. It was found that protein adsorption capacity (q_m) increased with increasing pAEM chain length, but the uptake rate, represented by the ratio of effective pore diffusivity to the free solution diffusivity (D_e/D₀), showed an up-down trend, reaching a peak value (D_e/D₀=0.55) at an IC of 313 mmol/L. Partial charge neutralization of the AEM-grafted resin of the highest IC (513 mmol/L) by reaction with sodium acetate produced three charge-reduced resins, FF-pAEM513-R. With reducing the charge density, the adsorption capacity kept unchanged and then decreased, but the uptake rate monotonically increased, reaching a maximum (about 2-fold increase) at a residual IC of 263 mmol/L. It is notable that, at the same IC, the charge-reduced resin (FF-pAEM513-R) presented similar or even higher values of q_m and D_e/D₀ than its FF-pAEM counterpart. Particularly, at the same IC of 263 mmol/L, a ~50% enhancement of D_e/D₀ was observed. Both adsorption capacity and uptake rate in the charge-reduced resin with a residual IC of 339 mmo/L (FF-pAEM513-R339) decreased more sharply with increasing NaCl concentration by comparison with FF-pAEM513, indicating its increased salt-sensitivity than FF-pAEM513. That is, charge reduction on the AEM-grafted resin could accelerate protein uptake at 0 mmol/L NaCl but decrease salt tolerance. Column breakthrough experiments showed that FF-pAEM513-R339 was favorable for high flow rate protein chromatography at low NaCl concentration (0 mmol/L), whereas FF-pAEM513 was a good choice in a wide range of salt concentrations at low flow rate. This research proved the excellent protein chromatography performance of the AEM-based anion-exchangers.