Green and chemical reduction approaches for facile pH-dependent synthesis of gold nanoparticles

This study compares the green synthesis method using the Lycium ruthenicum (L. Ru) with wet chemical extraction using citrate reduction to synthesize stable gold nanoparticles (AuNPs). The effect of pH on the synthesized AuNPs has also been evaluated in the present investigation. AuNPs were synthesized successfully by both methods, as well; by the way, there were reported differences between the microstructure of resulting powders. For AuNPs synthesized using the green method, a pH value of 3 was reported to be the optimum pH due to the characteristics of synthesized AuNPs. In the mentioned pH, the AuNPs were spherical, mono-dispersed, and highly crystalline, characteristic of a well-done synthesis. Both chemo- and biosynthesized AuNPs revealed a relatively smaller particle size (33.92 and 55.65 nm, respectively) with well-dispersed spherical morphology under alkaline conditions. This study revealed that employing L. Ru extract could be considered a simple, facile, and green technique in stimuli-sensitive AuNPs synthesis