Effect of different laser pulses on curcumin-assisted sliver nanohybrids: Structural, optical, and antibacterial activity

This study investigates the effect of laser pulse numbers ranging from 1000 to 4000, using a Nd:YAG laser (532 nm, 100 mJ), on curcumin -assisted silver nanohybrids synthesized via pulsed laser ablation (PLA) technique. Curcumin is a naturally occurring polyphenolic compound derived from turmeric. It has garnered considerable attention due to its biocompatibility, antioxidant properties, and extensive antimicrobial activity. It’s also use laser-assisted green synthesis to make silver nanoparticles (Ag NPs) that have better optical, structure and antibacterial characteristics. Optical and structure compositional analyses using XRD, EDX, SEM, and UV–visible spectrum. The XRD analysis of pure Ag, pure curcumin , and Ag/ curcumin nanohybrids synthesized at different laser pulse numbers (1000–4000) revealed a face-centered cubic (fcc) crystalline structure of metallic silver. The crystallite size was estimated to range from 14 to 15 nm, while the crystallite size of Ag/ curcumin nanohybrids at 1000–4000 pulses are 8–15.4 nm, indicating a pulse-dependent variation in crystal growth. EDX analysis of pure Ag, curcumin , and Ag/ curcumin nanohybrids synthesized at different laser pulse numbers (1000–4000) confirmed the elemental composition of Ag. The additional carbon and oxygen signals observed in the nanohybrids are associated with curcumin molecules acting as a capping and stabilizing agent on the nanoparticle surface. The particle size ranged from 26 to 45 nm for pure Ag and 47–65 nm for curcumin , while Ag/ curcumin nanohybrids showed a pulse-dependent variation with sizes of 24–31 nm (1000 pulses), 49–69 nm (2000 pulses), 25–38 nm (3000 pulses), and 31–54 nm (4000 pulses), indicating the influence of laser parameters on nanoparticle growth and aggregation behavior. The optical band gap increased from 2.61 eV for pure Ag to 2.91 eV for Ag/ curcumin nanohybrids prepared using PLA (Nd-YAG) technique at 4000 laser pulses, indicating the influence of curcumin incorporation and laser processing on the optical properties of the synthesized nanohybrids. The antibacterial activity results showed that pure curcumin exhibited an inhibition zone of 7 mm, while pure Ag NPs showed a value of 8.33 mm against Escherichia coli . The Ag/ curcumin nanohybrids demonstrated inhibition zones of 7.33, 9, 9.3, and 11 mm for samples prepared at 1000–4000 laser pulses, respectively. A gradual increase in antibacterial activity was observed with increasing laser pulse number, indicating a pulse-dependent enhancement in performance. This improvement is attributed to changes in nanoparticle size, surface area, and improved interaction with bacterial cells. These results suggest potential applications of the synthesized nanomaterials in antimicrobial and biomedical fields.