Cold plasma-assisted synthesis of silver nanoparticles using a sand-bath reactor and their antibacterial activity against E. coli
DOI:
https://doi.org/10.54939/1859-1043.j.mst.114.2026.151-158Keywords:
Silver nanoparticles; Cold atmospheric-pressure plasma; Sodium citrate; Antibacterial activity; E. coli.Abstract
Silver nanoparticles (AgNPs) are widely studied because of their strong optical response and antibacterial activity. In this work, AgNPs were synthesized by a cold atmospheric-pressure plasma-assisted method using AgNO3, NaBH4, and sodium citrate in a sand-bath reactor. The reaction was performed in a 25 mL glass beaker under Ar plasma treatment at 100 sccm and 60–70 °C. The plasma jet operated stably and produced OH, N2, and Ar emissions, indicating active plasma–liquid interaction. The effects of plasma irradiation time, citrate amount, and NaBH4 amount were investigated by UV-Vis spectroscopy. The optimized condition produced a yellow-orange AgNP colloid with a clear LSPR peak at 395–400 nm. After centrifugation at 9000 rpm for 5 min, the FWHM decreased from 82 to 70 nm. The optimized AgNPs had a hydrodynamic size of about 14 nm, a zeta potential of −24 mV, and a TEM size of 12.28 ± 2.04 nm. HR-TEM showed a lattice spacing of 0.23 nm. The plasma-synthesized AgNPs showed stronger inhibition against E. coli than commercial citrate-stabilized AgNPs. These results show that sand-bath plasma-assisted synthesis is a simple and effective route to prepare small AgNPs for antibacterial applications.
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