Superelastic Chitosan/Laponite Nanocomposite Sponges with Tunable Functional Properties as Promising Biomaterials for...

Fabrication and application of chitosan (CS)-laponite RD (LAP) nanocomposites as wound healing materials are scarcely mentioned in the literature. In this study, CS-LAP nanocomposite sponges were developed through two consecutive cryostructuration steps of CS in the presence of LAP nanoparticles, and their potential as intrinsic wound dressing materials was assessed in vitro. The as-prepared macroporous CS-LAP nanocomposites were characterized by FTIR, SEM, EDX, XRD, swelling, and compression tests. The morphology, swelling kinetics, and water uptake as a function of pH and compressive nominal stress were tuned by the concentration of LAP. When the LAP concentration increased from 0 to 2 wt %/v, at a concentration of CS of 4 wt %/v, the porosity decreased from 75.9 to 51%, and the average pore sizes decreased from 148 ± 34 μm to 97 ± 21 μm. Increasing the LAP content from 0.2 to 2 wt %/v resulted in a decrease of the compressive nominal stress from 560 to 375 kPa, while the compressive elastic modulus increased from 14 to 54 kPa. Cyclic compression tests on the CS4-LAP0.2 sample (at 100% strain) showed no significant loss of compressive strength after 10 cycles. All CS-LAP nanocomposite sponges were cytocompatible (with cell viability above 85%), and their wound healing capabilities were dependent on the LAP content. The highest wound healing rate was observed for the nanocomposite prepared with the lowest LAP concentration (CS4-LAP0.2), which exhibited a water uptake capacity of about 2000 wt % and an average pore size of 131 ± 27 μm. The bacteria killing rate of CS-LAP sponges against S. aureus and E. coli was ∼97% and ∼84%, respectively.