Local
bacterial infection is a challenging task and still remains a serious threat to human health in clinics. Systemic administration of
antibiotics has only short-term antibacterial activity and usually causes adverse effects and bacterial resistance. A bioadhesive
hydrogel with broad-spectrum and on-demand
antibiotic activity is highly desirable. Here, we designed a pH-responsive
nanocomposite hydrogel via a
Schiff base linkage between oxidized
polysaccharides and cationic
dendrimers encapsulated with
silver nanoparticles. The antibacterial components, both the cationic
dendrimers and
silver species, could be released in response to the acidity generated by growing bacteria. The released cationic
polymer and
silver exhibited a synergistic effect in antibacterial activity, and thus, the
nanocomposite hydrogel showed potent antibacterial activity against both Gram-negative ( Escherichia coli and Pseudomonas aeruginosa) and Gram-positive bacteria ( Staphylococcus epidermidis and Staphylococcus aureus). The gel showed superior in vivo antibacterial efficacy against S. aureus
infection compared with a commercial
silver hydrogel at the same
silver concentration. In addition, no obvious hemolytic toxicity, cytotoxicity, and tissue and biochemical toxicity were observed for the antibacterial
hydrogel after incubation with cells or implantation. This study provides a facile and promising strategy to develop smart
hydrogels to treat local
bacterial infections.