Preparation and evaluation of PAMAM dendrimer-based polymer gels physically cross-linked by hydrogen bonding.

Polymer gels can be classified as chemical and physical gels, depending on the type of cross-link. Physical gels usually form by physical cross-linking, such as hydrogen bonding, van der Waals and/or p-p interactions, which can avoid the use of additional cross-linking agents. Polyamidoamine (PAMAM) dendrimers possess abundant active groups on their surfaces. Modified dendrimers have been used as versatile linkers in some projects. In this work, polymer gels composed of PAMAM dendrimers without any covalent bonding cross-linking agents were prepared. The number of amino groups and ester groups on the surface of the dendrimers was precisely regulated to help form hydrogen bonds between adjacent dendrimers. The prepared dendrimer-based polymer gels retain the properties of PAMAM dendrimers such as antibacterial properties, and the unique structures make the gels exhibit high compressive strengths but relatively low tensile strengths. Interestingly, the prepared gels show good anti-inflammatory properties in acute inflammation models of mice with ear edema. The inflammatory inhibition rate and hematoxylin-eosin (H&E) staining method were used to confirm the anti-inflammatory effect. This present study demonstrates that the dendrimer-based polymer gels achieved through hydrogen bonding could be a versatile platform for tissue engineering.