Bio-Based Synthesis of Ag-Containing TiO2 Materials Using Cassava Starch and Propolis: Enhanced Antimicrobial Activity Against Escherichia coli

Bio-based approaches to advanced materials are receiving increasing attention because they enable the incorporation of renewable resources into material synthesis. In this study, Ag-containing TiO2 materials were prepared by conventional impregnation and a modified cassava-starch-assisted sol–gel route, with and without propolis extract, and their antimicrobial activity was evaluated against Escherichia coli ATCC 25922. Material suspensions were prepared at 0.5% (w/v), corresponding to 0.5 g of material per 100 mL of culture medium, and incubated at 35 °C for 24 h under dark conditions, without controlled irradiation. Bacterial viability was determined by the standard plate-count method using three experimental repetitions per material, with duplicate plate counts for each repetition. Pristine TiO2 did not differ significantly from the untreated control, whereas the Ag-containing formulations showed substantial reductions in bacterial counts. The incorporation of propolis was associated with further enhanced antimicrobial activity, with the S-P formulation showing no detectable colonies under the assay conditions, considering a detection limit of 1 CFU mL-1. These findings indicate that cassava starch and propolis can be incorporated as biomass-derived components in the preparation of Ag-containing TiO2 materials and that propolis incorporation was associated with enhanced antimicrobial performance under the conditions investigated. Further studies involving comprehensive physicochemical characterization, component-specific controls, additional microorganisms, concentration-response experiments, silver-release measurements, controlled irradiation tests, and quantitative environmental assessment are needed to clarify the mechanisms and broader applicability of these materials.