Laponite stabilized endogenous antibacterial hydrogel as wet-tissue adhesive.

Clinical adhesives for suture-less wound closure remain the problem of poor biocompatibility, weak adhesive strength, and no endogenous antibacterial ability. Here, we designed a novel antibacterial hydrogel (CP-Lap hydrogel) consisting of chitosan and ε-polylysine after being modified with gallic acid (pyrogallol structure). The hydrogel was crosslinked by glutaraldehyde and Laponite via Schiff base and dynamic Laponite-pyrogallol interaction, free from heavy metal and oxidants. Given its dual crosslinking feature, the CP-Lap hydrogel exhibited adequate mechanical strength (150-240 kPa) and demonstrated swelling and degradation resistance. For a typical lap shear test with pigskin, the apparent adhesion strength of the CP-Lap hydrogel could be enhanced to ∼30 kPa benefiting from the O2 blocking effect provided by nanoconfinement space between Laponite. In addition, the hydrogel showed effective antibacterial properties and excellent biocompatibility. The results indicated that this hydrogel has great potential for wound-closing bioadhesives to avoid chronic infections and further harm.

3D-printed antioxidant antibacterial carboxymethyl cellulose/ε-polylysine hydrogel promoted skin wound repair.

Developing a wound dressing for the treatment of large and irregular-shaped wounds remains a great challenge. Herein we developed novel printable bionic hydrogels with antibacterial and antioxidant properties which could effectively overcome the challenge by inhibiting inflammation and accelerating wound healing. The CMC/PL (CP) hydrogels were customized with glycidyl methacrylate (GMA) modified carboxymethyl cellulose (CMC) and ε-polylysine (ε-PL) via ultraviolet (UV) light polymerization using a 3D printer. Except for the high compression modulus (238 kPa), stable rheological properties, and effective degradability, these CP hydrogels also had an excellent inhibitory effect (95%) on both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Remarkably, CP hydrogels could remove the excessive reactive oxygen species (ROS) and protect the fibroblasts from damage. Compared with the commercial dressing (Tegaderm ™ film), CP hydrogels showed a better ability to increase the expression of VEGF and CD31, accelerate granulation tissue regeneration, and promote wound healing. This work provides a new strategy to fabricate on-demand multi-functional hydrogels in the field of skin tissue engineering.

Mono-acrylated isosorbide as a bio-based monomer for the improvement of thermal and mechanical properties of poly(methyl methacrylate).

Despite its optical clarity and good weatherability, poly(methyl methacrylate) (PMMA) cannot meet the needs of special occasions due to its deficient thermal and mechanical properties. To overcome these shortcomings, a type of novel bio-based monomer, mono-acrylated isosorbide, was used as a comonomer for the poly(methyl methacrylate) via a solution polymerization process. The chemical structure, the thermal and mechanical properties of the copolymerized PMMA were characterized. When the molar content of the mono-acrylated isosorbide was increased from 0% to 15%, the glass transition temperature T g of the copolymerized PMMA was increased from 151.2 °C to 172.5 °C, and the initial decomposition temperature (T 5%) was increased from 323.1 °C to 396.3 °C. Moreover, the impact strength of copolymerized PMMA increased from 10.59 kJ m-2 to 17.19 kJ m-2 and the tensile strength improved from 84.02 MPa to 97.56 MPa when the mono-acrylated isosorbide was incorporated with different contents. The incorporation of rigid and thermally stable isosorbide could contribute to the improved thermal and mechanical properties of PMMA, which would find important applications in the military and aeronautical materials under harsh service environments.