Urtica dioica-Loaded Alginate Hydrogels for Antibacterial Oral Applications: Formulation and In Vitro Evaluation

Introduction The increasing resistance of oral pathogens to conventional antibiotics has stimulated the search for alternative, plant-derived antimicrobial agents. Urtica dioica (nettle) is a medicinal plant widely recognized for its anti-inflammatory, antioxidant, and antimicrobial activities. This study aimed to synthesize a hydrogel loaded with Urtica dioica extract and evaluate its antibacterial activity against two significant oral pathogens: Staphylococcus aureus and Escherichia coli . Materials and Methods Ethanol extracts of nettle were incorporated into alginate hydrogels using a freeze-thaw synthesis technique. Characterization was carried out using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The antibacterial properties were assessed via the disc diffusion method. Results The hydrogels containing nettle extract demonstrated significant antibacterial activity against both tested strains. Zones of inhibition were significantly larger compared to blank hydrogels ( p < 0.001). FTIR confirmed successful integration of active compounds, while SEM revealed a porous microstructure suitable for controlled release. Discussion Herbal oral formulations, such as those containing Urtica dioica, offer sustainable alternatives for controlling oral pathogens. Postbiotics have also emerged as novel anti-caries agents, and combining them with herbal bioactives has the potential to enhance antimicrobial efficacy. Conclusion Nettle extract-loaded hydrogels appear to be promising candidates for novel oral formulations for oral health applications, including mouthwashes and dental gels aimed at preventing or treating infections.