*2.1. Materials*

The following polysaccharides were used: chitosan (CH) (β-(1-4)-linked d-glucosamine and N-acetyl-d-glucosamine) low MW 251 kDa, deacetylation degree 98%, (ChitoClear, Iceland); chondroitin sodium sulfate (CS) (β-1,4-linked d-glucuronic acid and β-1,3-linked N-acetyl galactosamine) bovine 100 EP, low MW 14 kDa, and a mixture of chondroitin A (chondroitin 4 sulfate) and chondroitin C (chondroitin 6 sulfate) (Bioiberica, Italy); pullulan (P) (based on maltotriose repeating units, linear α 1–4 and α 1–6 glucan, produced by *Aureobasidium pullulans*) low MW ~200–300 kDa (food grade, Hayashibara, Giusto Faravelli, Italy). Citric Acid (CA) (monohydrated citric acid, EP grade, Carlo Erba, I) was used as the crosslinking agent. Pharmaceutical grade clay minerals were considered: montmorillonite (MMT) (particle size: 1352 nm (±17); polydispersity index: 0.696 (±0.184)) (Veegum® HS, Vanderbilt, Nashville, TN, USA) or halloysite (particle size: 563 nm (±70); polydispersity index: 0.647 (±0.077); internal diameter = 28 ± 5.1 nm and external diameter = 70 ± 8.3 nm) (Halloysite Nanotubes—HTNs) (Sigma-Aldrich, St. Louis, MO, USA).
