Search

Hydrogels usually are fabricated by using monomers or preexisting polymers in precursor solutions. Here, a polyelectrolyte complex biohydrogel (Bio-PEC hydrogel) made from a precursor dough, by kneading, annealing, and crosslinking the dough of two oppositely charged polysaccharides, cationic chitosan quaternary ammonium salt (HACC) and anionic sodium hyaluronate (HA), photoinitiator (α-ketoglutaric acid), crosslinker glycidyl methacrylate (GMA), and water of very small quantity is reported. Controlled kneading and annealing homogenized the dough with respect to transforming randomly distributed, individual polymer chains into tightly wound double-stranded structures, which, upon UV irradiation, covalently sparsely crosslinked into a highly entangled network and subsequently, upon fully swollen in water, results in Bio-PEC hydrogel, HACC/HA, exhibiting near-perfect elasticity, high tensile strength, and high swelling resistance. Via the same kneading and annealing, tetracarboxyphenylporphyrin iron (Fe-TCPP) metal nanoclusters are incorporated into HACC/HA to obtain photocatalytic, antibacterial, and biocompatible Bio-PEC hydrogel composite, Fe-TCPP@HACC/HA. Using SD rat models, the efficacy of Fe-TCPP@HACC/HA in inhibiting Escherichia coli (E. coli) growth in vitro and the ability to promote wound healing and scar-free skin regeneration in vivo, or its high potential as a wound dressing material for biomedical applications are demonstrated., (© 2023 Wiley‐VCH GmbH.)

We report a simple and facile self-assembly approach to fabricate polyelectrolyte complex (PEC) hydrogel films with positively charged chitosan (CS) and negatively charged heparin sodium (HS) by combining hydrogen bonding and electrostatic interactions. The CS/HS hydrogel films exhibited excellent tensile strength and toughness, good self-recovery ability, superior water absorbency, and pH-dependent surface charge characteristics. The gelation mechanism was investigated by zeta potential measurements. The CS/HS hydrogel films exhibited high antibacterial efficacy against E. coli at selected pHs or when coordinated with various metal ions and a significant effect on accelerating wound healing. The self-assembly approach presented in this work may serve as a generic strategy for the fabrication of novel multi-functional PEC hydrogels for broad biomedical applications.

Chitosan (CS) has become a favorable choice for synthesizing hydrogels due to its hydrophilic and biocompatible nature. However, achieving robust CS-based hydrogels remains challenging. Herein, we propose a multiple mechanisms-based network design for mechanical enhancement in CS-based double-network (DN) composite hydrogels. In the DN composite gels, graphene oxide-filled CS-based network serves as the first network and polyacrylamide network is the second network. The multi-structure of the first network enhances its energy dissipation capacity; when combining with the second network to form DN structure, the coupling effect between the multiple mechanisms-based networks allows for much more energy dissipation, enabling synergistic enhancement in mechanical properties of the DN composite gels. By regulating the mechanics, we further explore the role of the individual networks. The results indicate that both the individual networks are essential: The first network primarily contributes to the energy dissipation, while the second network plays a role to the synergistic enhancement in the DN composite gels. This work provides an effective reinforcing strategy for CS-based composite hydrogels. [ABSTRACT FROM AUTHOR]

Chitosan (CS), a linear natural polysaccharide, is often chosen to prepare hydrogels due to its hydrophilic nature and biocompatible merits. However, mechanically weak CS-based hydrogels show limited applications. Herein, we show a new multi-structural network design for mechanically enhancing graphene oxide (GO) filled CS-based hydrogel nanocomposites. The designed multi-structural hydrogel network shows a relatively dense structure with surrounding polymer chains at the local zone of self-assembled GO-CS units and a relatively loose structure at the far zone, resulting in the mechanical enhancement. By tuning GO loading and molecular weight of CS in a specific range, we intend to understand the effect of the specific multiple network structures on the mechanical properties of the composites. The experimental results demonstrate that the multi-structural network design provides an effective reinforcement mechanism for the hydrogel composites. The composite (containing only 0.30 wt% GO and ≈90 wt% water) has achieved 163% and 91% increases in compressive strength and work of compression, respectively, comparing to those of the neat gel. The findings may be generally applicable for the structural design and understanding of nanofiller-reinforced hydrogel and elastomer composites. [ABSTRACT FROM AUTHOR]