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15. Brief Communication: Cellular Poly(arylene ether sulfone) With Pendant Sodium Carboxylate Groups: A Floatable Absorbent for Heavy Metal Ion Removal from Wastewater

Author

Ma, Dewang, Wang, Dazhi, Zhang, Shaoyin, and Cai, Weijie

Abstract

A novel poly (arylene ether sulfone) with sodium carboxylate groups was designed and synthesized through direct polycondensation. The as-prepared polymer possessed a cellular structure with an average pore size less than 10 μm and a tap density of 1.333 g/cm3. The cellular polymer exhibited lightweight property and excellent adsorption capacity for heavy metal ions in simulated wastewater. This might shed light on the development of cellular polymeric materials for heavy metal pollutant treatment.

Published
2016
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16. Prevention of Thermally Induced Aggregation of IgGAntibodies by Noncovalent Interaction with Poly(acrylate) Derivatives.

Author

Martin, Nicolas, Ma, Dewang, Herbet, Amaury, Boquet, Didier, Winnik, Françoise M., and Tribet, Christophe

Subjects
*IMMUNOGLOBULIN G, *BIOLOGICAL aggregation, *POLYACRYLATES, *AQUEOUS solutions, *COPOLYMERS, *DENATURATION of proteins, *POLYANIONS
Abstract

Prevention of thermal aggregationof antibodies in aqueous solutionswas achieved by noncovalent association with hydrophobically modifiedpoly(acrylate) copolymers. Using a polyclonal immunoglobin G (IgG)as a model system for antibodies, we have studied the mechanisms bywhich this multidomain protein interacts with polyanions when incubatedat physiological pH and at temperatures below and above the proteinunfolding/denaturation temperature, in salt-free solutions and in0.1 M NaCl solutions. The polyanions selected were sodium poly(acrylates),random copolymers of sodium acrylate and N-n-octadecylacrylamide (3 mol %), and a random copolymerof sodium acrylate, N-n-octylacrylamide(25 mol %), and N-isopropylacrylamide (40 mol %).They were derived from two poly(acrylic acid) parent chains of Mw5000 and 150000 g·mol–1. The IgG/polyanion interactions were monitored by static and dynamiclight scattering, fluorescence correlation spectroscopy, capillaryzone electrophoresis, and high sensitivity differential scanning calorimetry.In salt-free solutions, the hydrophilic PAA chains form complexeswith IgG upon thermal unfolding of the protein (1:1 w/w IgG/PAA),but they do not interact with native IgG. The complexes exhibit aremarkable protective effect against IgG aggregation and maintainlow aggregation numbers (average degree of oligomerization <12at a temperature up to 85 °C). These interactions are screenedin 0.1 M NaCl and, consequently, PAAs lose their protective effect.Amphiphilic PAA derivatives (1:1 w/w IgG/polymer) are able to preventthermal aggregation (preserving IgG monomers) or retard aggregationof IgG (formation of oligomers and slow growth), revealing the importanceof both hydrophobic interactions and modulation of the Coulomb interactionswith or without NaCl present. This study leads the way toward thedesign of new formulations of therapeutic proteins using noncovalent1:1 polymer/protein association that are transient and require a markedlylower additive concentration compared to conventional osmolyte protectingagents. They do not modify IgG permanently, which is an asset forapplications in therapeutic protein formulations since the in vivoefficacy of the protein should not be affected. [ABSTRACT FROM AUTHOR]

Published
2014
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17. The Design of Polysaccharide Multilayers for Medical Applications

Author

Dewang Ma, Benjamin Thierry, Françoise M. Winnik, Thierry, Benjamin, Ma, Dewang, and Winnik, Françoise M

Subjects
chemistry.chemical_classification, Materials science, Heparin, heparin, Pharmacology, Polysaccharide, Carrageenan, Cardiovascular therapy, hyaluronan, Chitosan, chemistry.chemical_compound, cardiovascular therapy, chemistry, drug delivery, Drug delivery, carrageenan, medicine, chitosan, medicine.drug
Abstract

Polysaccharides form an important class of natural polymers with critical structural functions and biological activities in plants and all living organisms. It comes as no surprise that polysaccharides are key players in the area of biomaterials, where they have found applications in fi elds as diverse as drug delivery, tissue engineering and regenerative medicine, biosensing and biodiagnostics. Nonetheless, in the early phase of polyelectrolyte multilayers development, up to ~2002, there were only a few studies of layer-by-layer (LbL) assemblies containing polysaccharides. These natural polymers, intrinsically, are more difficult to handle than synthetic polymers or proteins that can be defined precisely in terms of structure, architecture, and molecular weight. Polysaccharides consist of carbohydrate units linked by glycosidic bonds and occur naturally with a range of molecular weights. Specific substituents, such as hydroxyls, sulfates, carboxylates, and amines linked to the glycoside rings, directly control the physicochemical and biological properties of polysaccharides. They also affect the multilayer assembly process, often in unpredictable ways. In addition, polysaccharides undergo facile degradation in strong acidic or alkaline environments. Hence, the multilayer construction conditions need to be selected carefully in order to avoid undesired side-reactions.

Published
2012
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