Macromolecular Bioscience

Front Cover: Glucose-responsive hydrogels have been prepared by immobilizing the glucose/galactose binding protein within an acrylamide hydrogel network. These hydrogels demonstrate “accordion”-like dynamic behavior in response to glucose, allowing for controlled transport of molecules across the glucose sensitive hydrogels. Further details can be found in the article by J. D. Ehrick, M. R. Luckett, S. Khatwani, Y. Wei, S. K. Deo, L. G. Bachas, S. Daunert^*on page 864.

It is of great interest to develop multifunctional nanomaterials that are smaller but more stable than antibodies for targeted cell labeling. The purpose of this research is to demonstrate that a new type of sub-10 nm hybrid nanomaterial can be readily synthesized with a nucleic acid aptamer and a dendrimer as structural units, and that this nanomaterial can recognize target cells with high binding affinity and specificity.

Melts of inorganic and organic salts are known as cellulose solvents and reaction medium for the homogeneous conversion of the polymer. However, they are rather expensive and most of them contain large amounts of water, which may induce side reactions. Melts of simple trialkylammonium salts could be an inexpensive alternative. Thus, trialkylammonium carboxylates were synthesized and studied as potential solvents and reaction medium for the homogeneous etherication of cellulose.

Hydrophobically modified γ-poly(glutamic acid) (γ-hPGA) was synthesized by grafting hydrophobic amino acids to γ-PGA. To regulate the size of γ-hPGA NPs, the γ-hPGA copolymers dissolved in DMSO were added to various concentration of NaCl solution. The size of the NPs increased with increasing NaCl concentration. The size of γ-hPGA NPs could be easily controlled by altering the NaCl concentration without any structural change of the NPs.

Films that consist of a blend of cellulose and corn protein overcome the disadvantages of the pure protein films (friable and water-soluble), and exhibit improved proliferation of HeLa cells (Fig. a,b), a good optical transmittance (Fig c), and mechanical properties. The blend films with features of safeness, biocompatibility, and biodegradability have promising applications in the field of biomaterials.

Quaternized cellulose (QC) nanoparticles as novel protein carriers were successfully prepared by ionic crosslinking of QC with sodium tripolyphosphate. QC nanoparticles displayed high loading efficiency and capacity for BSA and their physicochemical properties and release profile could be easily adjusted.

A glucose-responsive hydrogel has been synthesized by immobilizing the glucose/galactose binding protein within an acrylamide hydrogel network. This hydrogel demonstrates “accordion”-like dynamic response to glucose, thus rendering the transport of marker molecules across the hydrogel sensitive to glucose.

We discuss the reverse thermal gelation of methoxy-aminopoly(ethylene glycol)-polypeptide block copolymer chloroform solutions that undergo a sol-to-gel transition as the temperature increases. This is the opposite behavior to traditional organogels. The polypeptide can take on a β-sheet or α-helix morphology, and the particular morphology, which is influenced by the chain length of the methoxy- aminopoly(ethylene glycol) component influences the morphology of the gel: spherical micelles/short tubular structure or a fibrous structure.

Gelatin was quinone crosslinked in aqueous phase by treatment with HQ and a simple copper(II) salt under oxygen atmosphere. The hydrogel and the film of the crosslinked protein were thermally stable and mechanically strong. The crosslink formation is discussed in consideration of a copper(II) ion catalyzed oxidation of HQ and the protein/quinone adducts.

Novel nanofibrous materials containing silver nanoparticles were electrospun from chitosan or N-carboxyethylchitosan solutions in formic acid by reactive electrospinning in the presence of poly(ethylene oxide). Water-stable mats were obtained by cross-linking with glutaraldehyde. The obtained materials are promising as wound healing dressings or antibacterial filters.

Injectable alginate hydrogels with shear-reversible gelation behavior can be prepared by combination crosslinking using cell-crosslinking and ionic crosslinking techniques. The addition of a small quantity of calcium ions can decrease the number of cells which are required to form cell-crosslinked hydrogels without changing the shear reversibility. Gels are useful to engineer cartilage tissues in vivo.

PEG-grafted copolymers with protonizable segments were synthesized and novel supramolecular physical hydrogels were obtained by threading PEG grafts with α-CDs in aqueous solution. It was found that the gel/sol transformation was affected by polymer concentration, polymer chain uniformity, PEG graft densities, temperature and pH of solution. Encapsulating and releasing BSA using the hydrogels were explored.

U937 monocytes were cultured on N-rich organic coatings with well-characterised surface chemistries, deposited by plasmaand vacuum ultraviolet photo-polymerisation. By comparing those materials that trigger cell-adhesion, we demonstrated the dominant role of primary amines in the adhesion mechanism. RT-PCR analyses of adhering cells displayed a transient expression of cytokines, but a more sustained expression of genes implicated in the adhesion and retention of monocytes.

We present a versatile strategy for the immobilization of Subtilisin A to surfaces using different types of maleic anhydride copolymer coatings for the covalent anchorage of the enzyme. The performance of the immobilized enzyme was shown to be influenced by the physicochemical characteristics of the polymer support. Higher amounts and activities of the protease were obtained on hydrophilic, swollen (PEMA) coatings.

Back Cover: Amphiphilic graft copolymers composed of poly(γ-glutamic acid) (γ-PGA) and hydrophobic amino acid (HAA) were prepared. By regulating the aggregation of the amphiphilic graft copolymers, the size of the nanoparticles was easily controlled. Further details can be found in the article by H. Kim, T. Akagi, M. Akashi^*on page 842.