Conclusion
Metal dispersion in the form of AgNPs and CuNPs with polyol dendrimer
resulted in higher antibacterial activity than merely spread on a solid
surface of montmorillonite or cellulose fibers. Both cellulose and clay
act as host matrices for MNP when previously coated by BoltornH20.
Polyol dendrimer incorporation induces no detectable antibacterial
activity but provides additional hydroxyl groups that act as chelating
agents for both MNPs and metal cations. The strength of the –HO:Metal
interaction plays a key-role in metal retention/release processes and,
subsequently, in the antibacterial activity of the metal loaded
polyol-clay or polyol-cellulose composite against both Gram-positive and
Gram-negative bacteria. Weaker retention of CuNPs and its involvement in
oxidative damage explains, at least in part, the higher antibacterial
activity of CuNPs as compared to silver counterparts. The occurrence of
an optimal amount of metal-loaded polyol composites for achieving a high
biocidal effect is attributed to structure compaction and diffusion
hindrance of metal species at abundant number of -OH groups
incorporated. Research is still in progress for designing even more
effective antibacterial matrices with natural and low-cost materials and
modulable entanglement porosity.