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.