Hydrophilic Thiol‐Functionalized Silver Nanoparticles as Bio‐Stimulants in Quercus Pubescens Seedling Development

ABSTRACT Silver nanoparticles functionalized with the 3‐mercapto‐1‐propanesulfonate thiol (AgNPs‐3MPS) were synthesized via wet chemical reaction in water and evaluated for their effects on Quercus pubescens seedlings under confined growth conditions. Physicochemical characterizations (UV–vis, DLS, ζ‐potential, FESEM‐EDX, FTIR/Far‐IR, and 1 H‐NMR) confirmed the formation of stable, spherical, non‐aggregated nanoparticles with solid‐state diameter of (22 ± 3) nm, hydrodynamic diameter of (48 ± 20) nm, and ζ‐potential of (−32 ± 8) mV, with a retained colloidal stability for up to 30 days due to covalent Ag─S interactions and negatively charged surface sulfonate groups. Seedlings exposed to increasing AgNPs‐3MPS concentrations (0.1–50 µg/mL) for a period of 45 days showed a clear concentration‐dependent response. The lowest concentration tested (0.1 µg/mL, Ag content = 0.0418 µg/mL by ICP‐OES) enhanced root development, increasing the number of root tips, while maintaining physiological chlorophyll levels. In contrast, concentrations ≥10 µg/mL induced chlorophyll reduction and triggered visible stress symptoms, indicating the onset of phytotoxicity after prolonged exposure. FESEM–EDX analyses confirmed preferential nanoparticle accumulation in root tissues with limited translocation to aerial organs. These findings highlighted that AgNPs‐3MPS hydrophilicity and loading played central roles in governing AgNPs effects on seedlings, providing a basis for designing tailored nanomaterials for sustainable environmental applications.