This work presents a systematic rheological study of the gelatinization process of corn-starch plasticized with glycerol, showing the effects of the glycerol/starch ratio, water/starch ratio, and clay (montmorillonite) content. Gelatinization temperatures at different heating rates in rheological oscillatory temperature-sweep experiments were determined for different corn-starch/glycerol/clay formulations. The influences of the different formulation variables on the gelatinization processes and on the gel properties are analyzed. Some hypotheses postulating how the different intermolecular interactions present in the composites are responsible for these effects are discussed.

We investigated the migration behavior of rodlike double-stranded DNA (dsDNA) in polymer gels and polymer solutions. Tetra-PEG gel, which has a homogeneous network structure, was utilized as a model system, allowing us to systematically tune the polymer volume fraction and molecular weight of network strand. Although we examined the applicability of the existing models, all the models failed to predict the migration behavior. Thus, we proposed a new model based on the Ogston model, which well explained the experimental data of polymer solutions and gels. The polymer volume fraction determined the maximum mobility, while the network strand governed the size sieving effect. From these results, we conclude that the polymer network with lower polymer volume fraction and smaller network strand is better in terms of size separation. The homogeneous polymer network is vital for understanding of particles’ dynamics in polymer network and a promising material for high-performance size separation.

Peptides have become attractive molecules for fabricating biomaterials. Studies of peptide structure, assembly properties, and dynamic behavior in response to external parameters have led to rational novel design of peptide biomaterials. One model sequence selected was a β-spiral motif of spider flagelliform silk protein, [GPGGX]n (X = any amino acid). Modifying the X residue can change the quantity of secondary structure and the stability of this spider silk motif. Glycine provides flexible properties, and proline influences the secondary structure and mechanical properties. Another model sequence was GXGXDXUX (U = hydrophobic residue), a Ca2+ binding domain of lipase Lip A from Serratia marcescens, in which aspartate residue is required for ion binding. Combining with [GPGGX]n, we rationally designed peptide as GPGGDGPGGD (eD2). The Ca2+ binding sequence was hidden in the first eight residues of eD2. As expected, this peptide can assemble into nanofibrils triggered by Ca2+ ions. Using the segment FLIVIGSII (h9) from the third trans-membrane segment of subunit IV in the dihydropyridine sensitive human muscle L-type calcium channel as the hydrophobic motif, we obtained FLIVIGSIIGPGGDGPGGD (h9e) peptide. The h9e self-assembled into nanofibrils and further formed shear-thinning and rapid recovery hydrogel in neutral pH range from 6.0 to 8.0 with a large working range of temperature. NMR study showed that amphiphilic structure of h9e peptide tended to adopt a more helical structure during hydrogel formation. The h9e peptide has great potential for biomedical applications. MCF-7 cells were successfully grown as colony-like clusters (reminiscent of real tumors) in h9e hydrogel system. The drug response test of cisplatin further demonstrated the capability of h9e system for drug screen. Moreover, h9e hydrogel showed a promising adjuvanticity by enhancing the vaccine efficacy for killed H1N1 swine influenza virus and PRRS modified live virus.

Chondroitin sulfate (CS) is one of the major glycosaminoglycans (GAGs) present in the connective tissue extracellular matrix (ECM) and is responsible for the regulation of cellular activities as well as providing mechanical support for the surrounding tissue. Due to presence of CS in the natural tissues including cartilage, hydrogels of CS and other GAGs have been widely used in cartilage regeneration. Due to their polyelectrolyte nature, GAG-based hydrogels are brittle and require modifications to overcome the weak mechanical properties. In this work, we showed copolymerization of methacrylated chondroitin sulfate with oligo(ethylene glycol)s improved the crosslink density of the gels from 2 to 20 times depending on the methacrylation degree of CS and length of the crosslinking monomer. Copolymerization of CS with oligo(ethylene glycol) acrylates is a method to design hydrogels with tunable swelling and mechanical properties.