The production of paper based bacterial cellulose-chitosan (BC-Ch) nanocomposites was accomplished following two different approaches. In the first, BC paper sheets were produced and then immersed in an aqueous solution of chitosan (BC-ChI); in the second, BC pulp was impregnated with chitosan prior to the production of the paper sheets (BC-ChM). BC-Ch nanocomposites were investigated in terms of physical characteristics, antimicrobial and antioxidant properties, and ability to inhibit the formation of biofilms on their surface. The two types of BC-Ch nanocomposites maintained the hydrophobic character, the air barrier properties, and the high crystallinity of the BC paper. However, BC-ChI showed a surface with a denser fiber network and with smaller pore than BC-ChM. Only 5% of the chitosan leached from the BC-Ch nanocomposites after 96 h of incubation in an aqueous medium, indicating that it was well retained by the BC paper matrix. BC-Ch nanocomposites displayed antimicrobial activity, inhibiting growth and having killing effect against the bacteria S.aureus and P.aeruginosa, and the yeast C.albicans. Moreover, BC-Ch papers showed activity against the formation of biofilm on their surface. The incorporation of chitosan increased the antioxidant activity of the BC paper. Paper based BC-Ch nanocomposites combined the physical properties of BC paper and the antimicrobial, antibiofilm and antioxidant activity of chitosan.

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Eucalyptus and bacterial celluloses were functionalized by oxidation with a lytic polysaccharide monooxygenase, SamLPMO10C, to increase their contents in carboxyl groups by 2.4 and 2.7-fold, respectively. The functionalized celluloses were used to generate paper supports containing silver nanoparticles. A solution of silver nitrate was added to oxidized celluloses as a source of Ag+ which allowed the interaction between silver cations and hydroxyl or carboxyl groups. Following, paper supports were produced, and the formation of silver nanoparticles was induced by heat reduction. The presence of silver nanoparticles was validated by scanning electron microscope and energy-dispersive X-ray spectroscopy. Inductively coupled plasma-optical emission spectrometry and inductively coupled plasma mass spectrometry tests allowed to measure the silver content in the paper supports as well as the migration of silver in an aqueous media. The Ag-functionalized paper supports showed strong antibacterial properties against Staphylococcus aureus.