Preparation and characterization of novel physically cross-linked hydrogels composed of poly(vinyl alcohol) and amine-terminated polyamidoamine dendrimer

Poly(vinyl alcohol)(PVA) and polyaminoamine (PAMAM) dendrimers are water-soluble, biocompatible and biodegradable polymers, which have been widely applied in biomedical fields. In this paper, novel physically cross-linked hydrogels composed of PVA and amine-terminated PAMAM dendrimer G6-NH2 were prepared by cyclic freezing/thawing treatment of aqueous solutions containing PVA and G6-NH2. The FT-IR analysis and elemental analysis indicated that PAMAM dendrimer G6-NH2 was successfully introduced into the formed hydrogels, possibly via hydrogen bonds among hydroxyl groups, amide groups and amino groups in PVA and PAMAM dendrimer in the process of freezing-thawing cycle. Compared with physically cross-linked PVA hydrogel, PVA/G6-NH2 hydrogels show higher swelling ratios and faster re-swelling rate due to the higher hydrophilicity of PAMAM dendrimer G6-NH2. Higher contents of G6-NH2 in PVA/G6-NH2 hydrogels resulted in higher swelling ratios and faster re-swelling rates. With increasing freezing/thawing cyclic times, the swelling ratios and re-swelling rates of PVA/G6-NH2 hydrogels decreased, which is similar to that of physically cross-linked PVA hydrogel. Combining the special host property of polyamidoamine dendrimer, these novel physically cross-linked hydrogels are expected to have potential use in drug delivery, including improving drug-loading amounts in hydrogels and prolonging drug release time.