Green Synthesis of Mesquite-Gum-Stabilized Gold Nanoparticles for Biomedical Applications: Physicochemical Properties and Biocompatibility Assessment.

Using cytotoxic reducing and stabilizing agents in the synthesis of gold nanoparticles (AuNPs) limits their use in biomedical applications. One strategy to overcome this problem is using "green" synthesis methodologies using polysaccharides. In the present study, we propose a green methodology for synthetizing AuNPs with mesquite gum (MG) as a reducing agent and steric stabilizer in Gold(III) chloride trihydrate aqueous solutions to obtain biocompatible nanoparticles that can be used for biomedical applications. Through this method, AuNPs can be produced without using elevated temperatures or pressures. For synthetizing gold nanoparticles coated with mesquite gum (AuNPs@MG), Gold(III) chloride trihydrate was used as a precursor, and mesquite gum was used as a stabilizing and reducing agent. The AuNPs obtained were characterized using UV-Vis spectroscopy, dynamic light scattering, transmission electron microscopy, scanning transmission electron microscopy, and FT-IR spectroscopy. The stability in biological media (phosphate buffer solution), cytotoxicity (MTT assay, hematoxylin, and eosin staining), and hemocompatibility (Hemolysis assay) were measured at different concentrations and exposure times. The results showed the successful synthesis of AuNPs@MG with sizes ranging from 3 to 30 nm and a zeta potential of -31 mV. The AuNPs@MG showed good colloidal stability in PBS (pH 7.4) for up to 24 h. Finally, cytotoxicity assays showed no changes in cell metabolism or cell morphology. These results suggest that these gold nanoparticles have potential biomedical applications because of their low cytotoxicity and hemotoxicity and improved stability at a physiological pH.