Antibacterial and anti-inflammatory chitosan films incorporating recombinant collagen functionalized mesoporous bioactive glass nanoparticles for skin wound healing

Chitosan (CH) is a well-known biocompatible, antibacterial biopolymer with distinct merits (e.g., infection control) for wound healing. However, like many other biopolymers, its bioactivity and mechanical stability are limited and need to be improved to promote the wound healing process. In this study, CH films were strengthened and biofunctionalized through incorporation of recombinant collagen type III (rCol) loaded mesoporous bioactive glass nanoparticles (mBGNPs). The addition of rCol not only supplies further biochemical cues for promotion of cell activities and raises bioactivity, but also firmly links CH and mBGNPs through physicochemical bonds, thereby assuring uniform distribution of the nanoparticles within the CH matrix. In this study, it was shown that inclusion of rCol-mBGNPs increases the mechanical properties of the CH composite film compared to the pristine CH films, as reflected in notably enhanced stiffness (516 MPa vs. 208 MPa) and tensile strength (52 MPa vs. 28.5 MPa). Additionally, rCol-mBGNPs could stimulate the L929 cell viability and cell migration through the co-release of pro-healing ions such as Ca2+ and rCol molecules and endowed the CH films with a bioactivity effect, reflected in the formation of a calcium phosphate surface biomineral layer. The rCol-mBGNP/CH composite film could successfully inactivate gram-positive (S. aureus) and gram-negative (E. coli) bacteria. Furthermore, in vivo studies revealed the raised collagen deposition and accelerated wound closure rate of the CH composite films containing rCol-mBGNPs and their anti-inflammatory and pro-epithelialization effect. Taken together, rCol-mBGNP/CH composite films were shown to possess favourable mechanical and biological properties that make them an attractive choice for wound healing applications.