Novel Silver Complexes as Additives for Innovative Composite Materials with Permanent Antimicrobial Activity

In summary, most of the experimental work of my PhD thesis has been devoted to develop novel silver complexes with suitable physico-chemical properties for their employment as additives in antimicrobial composite materials with persistent activity. Among the most relevant results, the silver coordination polymers seem to be the most effective for their application as additives, due to their high and broad spectrum antimicrobial activity. Such activity is persistent in time, likely because of a contact mechanism of toxicity against bacteria, due to exposed silver centers within the polynuclear chain, which are able to attract the negatively charged cell membranes of bacteria altering their membrane potential and provoking their death. In any case, the release of silver ions from the composite material seems very limited or absent, thanks to the insolubility of such silver coordination polymers in almost all solvents and water, an essential feature for their application as additives for plastics. Future developments of this research will be directed to optimize the homogeneity of the composites' surfaces by changing the substituents in the HQR proligands with the aim of increasing their hydrophobicity and solubility in the polymeric matrices.