Cross-linker and non-gelling Na+ effects on multi-functional alginate dressings

This study investigated the effects of Ca2+, Cu2+ and Zn2+ as well as added Na+ during cross-linking on the mechanical properties of cross-linked alginates and also their potential to release cations in infected wounds. All these variables were found to affect the functional properties of the alginate films to varying extent. The added Na+ increased the tensile strength of the films cross-linked by Ca2+ but it exerted the opposite effect on those cross-linked by Cu2+ or Zn2+. Employing a combination of cross-linking cations resulted in greater extent of cross-linking but variable effect on tensile strength. The added Na+ also influenced the release of cations from alginate matrices to different extents in pH 4.0 and 8.0. The percentage of cations released from the films was lowest for Cu2+ but relatively high for Ca2+ and Zn2+. Hence, careful selection of cations is important to ensure that the functions of the alginate dressings are not compromised.