Exploring the medical applications of silver-enhanced urine mixtures: Towards sustainability in radiological treatment and dosimetry

Damage to healthy tissues and the high cost of treatment remain major challenges in radiotherapy. This study explores the potential of silver-enhanced urine mixtures (HUSM) as an innovative dosimetric and radiosensitizing agent for radiological cancer treatment. The results demonstrate that human urine provides superior stabilization of silver nanoparticles compared to conventional stabilizers, owing to its unique electrolyte composition. The efficacy of silver nanoparticles in amplifying radiation effects on cancer cells, enhancing DNA damage, and improving radiotherapy efficiency while minimizing exposure to healthy tissues was systematically evaluated. HUSM was prepared by reducing AgNO₃ in human urine, yielding 5.03 ± 0.21 μg/mL of AgNPs, and subsequently concentrated using direct-contact membrane distillation (DCMD) (0.22 μm PTFE membrane, ΔT = 50 °C). A theoretical retention efficiency of 95.2%, based on feed and permeate ICP-MS analysis, was achieved, consistent with literature benchmarks. Cancer cells were treated with HUSM and irradiated using a linear accelerator. The radiosensitizing effectiveness of HUSM was assessed by measuring the dose enhancement ratio (DER) and γ-H2AX foci formation, a well-established indicator of DNA damage. Phosphorus content was analyzed to elucidate its role in silver nanoparticle stabilization. The study revealed that HUSM significantly enhanced the DER, increasing from 1.00 (control) to 1.40 in HUSM-treated cells (p = 2.3 × 10⁻⁵, Cohen’s d = 1.8). Phosphorus-mediated stabilization via Ag₃PO₄ surface complexes (Ksp = 8.89 × 10⁻¹⁷) was inferred from zeta-potential shifts (−18 to −32 mV) and Ag:PO₄³⁻ stoichiometry (2.8:1), explaining the improved nanoparticle stability and enhanced dose amplification. Furthermore, γ-H2AX foci increased from 15 to 35 per nucleus (p < 0.001), indicating substantially increased DNA damage. Overall, human urine-stabilized silver nanoparticles offer a sustainable and effective strategy for enhancing cancer radiotherapy at approximately 100-fold lower cost than gold nanoparticle-based approaches.