The Moderato project aims at designing novel families of chemically modified polysaccharides, to be used as bio-based functional coatings in order to impart paper materials with barrier properties, which will be enhanced and maintained upon changes of relative humidity and temperature, for end-uses in the flexible food packaging field.  The novelty is to exploit the appealing Passerini-three component reaction (P-3CR), and to apply it to both polysaccharide chains (carboxymethyl cellulose, alginic acid) and cellulose particles (oxidized cellulose microfibrils, MFCs) to graft onto the biopolymer backbone and at the surface of MFCs judiciously chosen hydrophobic and/or thermosensitive derivatives. After two intensive tasks of synthesis and detailed characterization, the P-3CR modified biosourced polymer chains and particles will be coated onto cellulosic/paper substrates by using well-managed physical deposition processes. The adsorption and film-forming mechanisms as well as the (topo)chemical, physico-chemical, and morphological features of the coatings will be investigated in-depth in a third task, while a final fourth task will be focused on the barrier properties against liquids (H₂O, grease), and gazes (water vapor, O₂), the recyclability ability, the harmlessness and the economic viability of the coated cellulosic substrates.