Poly(2-ethyl-2-oxazoline) grafted gellan gum for potential application in transmucosal drug delivery

Gellan gum (GG) has been used to prepare polymeric carriers with prolonged retention on the eye surface for topical ocular drug delivery. In this work, GG was chemically modified with short poly(2-ethyl-2-oxazoline) (PEtOx) chains that were expected to have minimal adhesion to mucosal tissues (mucoadhesion). The choice of synthetic procedure, solvents, and reagents has been dictated by biocompatibility of the materials and possible application in drug delivery. The grafts were synthesized via cationic ring-opening polymerization and their living chains were attached onto deprotonated gellan backbone. The derivatives with three degrees of grafting were prepared by varying the in-feed mass ratio of PEtOx grafts over GG. NMR and FT-IR spectroscopies, thermogravimetric analysis, and SEC evidenced that the grafting had actually taken place. However, a greater diffusion coefficient determined for the copolymer, using diffusion-ordered spectroscopy (NMR), in relation to the diffusion of the unmodified GG, suggested either partial degradation of the backbone or a more compact structure of the copolymer. GG and its graft copolymers (GG-g-PEtOx) were found to be highly biocompatible with cells cultured under their induction at concentration of 1, 0.1 and 0.01 mg/mL demonstrated a physiological morphology, as well as an increase in viability and proliferation.Peer reviewe

Highly stretchable and thermally healable polyampholyte hydrogels via hydrophobic modification

Aqueous solutions or gels of polyampholytes attract interest for more than half a century due to their several attractive properties. We present here thermally healable hydrophobically modified physical polyampholyte (PA) hydrogels based on oppositely charged 2-acrylamido-2-methylpropane-1-sulfonic acid sodium salt (AMPS) and (3-acrylamidopropyl) trimethylammonium chloride (APTAC) monomers. PA hydrogels were prepared via micellar polymerization technique in the presence of the hydrophobic monomer n-octadecyl acrylate (C18A) in aqueous sodium dodecyl sulfate (SDS) solutions. Charge-balanced PA hydrogels containing 60-90% water exhibit a high tensile strength and stretchability of up to 202 kPa and 1239%, respectively. Above 7 mol% C18A, swollen hydrogels containing around 90% water exhibit much better mechanical properties as compared with the corresponding as-prepared ones because of the stronger hydrophobic interactions in the absence of SDS micelles. Cut-and-heal tests conducted at 50 degrees C reveal a complete healing efficiency with respect to Young's modulus for all as-prepared PA hydrogels within 1-4 h