Development of an Alginate Gel Composite with Antibacterial Properties Capable of Binding Calcium-Based Residual Stone Fragments in Endoscopic Stone Surgery

<b><i>Background:</i></b> Complete removal of urinary stones remains a challenge, as residual fragments can contribute to recurrence and postoperative urinary tract infections. This study presents an initial laboratory investigation into the development of an alginate gel composite designed to bind calcium-based stone remnants and exhibit antibacterial properties. <b><i>Methods:</i></b> To evaluate gel formation, calcium oxalate powder reagent and sodium alginate (SA) powder reagent were mixed in a Becker glass and stirred on a hot plate. Stones from 17 patients who underwent stone surgery were crushed, and gel formation was confirmed using the same experimental conditions with SA powder reagent. A gel composite material containing silver nitrate and vancomycin was prepared, and antibacterial activity against <i>Staphylococcus aureus</i> and <i>Escherichia coli</i> was tested over a 5-minute period. A mixture of 0.5 g alginic acid and 0.05 g calcium oxalate monohydrate powder reagent with 50 mL distilled water formed a gel after 30 minutes. <b><i>Results:</i></b> Sandy stones composed of calcium oxalate formed a better gel composite when mixed with SA than those composed of uric acid. In the antibacterial test of the alginate gel composite containing silver nitrate and vancomycin against <i>S. aureus</i> and <i>E. coli</i>, the number of live bacteria in the control and alginate gel composite was 3.5 × 10³ and <10, respectively. <b><i>Conclusion:</i></b> This study represents a preliminary laboratory investigation into the development of an alginate gel composite for potential use in urinary stone management. Further preclinical studies are necessary to evaluate its efficacy and safety before clinical translation.