Chitosan-Polyoxometalate Nanocomposites: Synthesis, Characterization and Application as Antimicrobial Agents

Abstract

Polyoxometalates (POMs) were used, together with chitosan (CS), to obtain hybrid nanoaggregates. Three representative POMs were efficiently assembled into nanoparticles of few hundred nm diameter, featuring entangled ribbons substructure. In order to establish suitable preparation and stability conditions, the assemblies were characterized in solution by UV-Vis spectroscopy, dynamic light scattering and f-potential. The nanoparticles were tested against E. coli (10 6 CFU/ ml) in aqueous solution, showing a synergic activity of the heteropolyacid H 5 PMo 10 V 2 O 40 and CS. For such components, a highly porous and antibacterial film was obtained upon lyophilisation of the colloidal mixture.

The antibacterial activity of polyoxometalates: structures, antibiotic effects and future perspectives

“…Fiorani et al tested several nanocomposites derived from low-molecular weight CTs and different POM-types, namely decavanadate [V 10 O 28 ] 6– , the phosphovanadomolybdic Keggin-structure [PMo 10 V 2 O 40 ] 5– and decatungstate [W 10 O 32 ] 4– , regarding their antibacterial activity against Escherichia coli and their surface charge. 76 All nanocomposites were antibacterially active in a dose-dependent manner, whereby systems exhibiting an in total more positively charge (CT-[PMo 10 V 2 O 40 ] 5– and CT-[W 10 O 32 ] 4– ) were more active than less positively charged systems (CT-[V 10 O 28 ] 6– ). This suggests, in this case, a direct correlation between the activity and the ζ-potential (surface charge) of the nanocomposites as those bearing a more positive charge were able to completely inhibit the bacterial growth (at a concentration of 0.6 mg ml –1 ) and induce morphological changes of the cells.…”

Synthesis and biological activity of an Anderson polyoxometalate bis‐functionalized with a Bombesin‐analog peptide

“…Among small inorganic systems with biological activity, polyoxometalates (POMs) are multimetallic and polyanionic oxides, with interesting potential applications in nanomedicine as low cost antibacterial, antiviral, and antitumoral agents.…”

Cytotoxicity and enzyme inhibition studies of polyoxometalates and their chitosan nanoassemblies

“…Moreover, POMs were reported to stimulate insulin secretion and regenerate pancreatic beta cell function in rodents [25] , [26] , [27] , [28] , [29] , [30] , [31] . POMs are also very effective in treating bacterial [32] , [33] , [34] and viral [35] , [36] , [37] , [38] diseases. A very recent study shows the ability of POMs, specifically [TeW 6 O 24 ] 6− , to act as a co-crystallization agent in the isolation and crystallization of the latent isoform PPO4 mushroom ( Agaricus bisporus ) tyrosinase protein which helps in the catalytic activity of phenols oxidation to quinones which in turn are responsible for the generation of melanins by polymerization [39] .…”