Biosynthesis of uniform ultra-small gold nanoparticles by aged Dracaena Draco L extracts

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 581; p. 123744
• Main Authors: Luna, Manuel, Zarzuela, Rafael, Mosquera, María J., Gil, M.L. Almoraima, Cubillana-Aguilera, Laura M., Delgado-Jaén, Juan J., Palacios-Santander, José M., García-Moreno, Valme, Carmona-Jimenez, Yolanda
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 20.11.2019
• Subjects: Ageing extract; Biosynthesis; Dragon tree leaf extract; Experimental design linked to simplex; Gold nanoparticles; Experimental design linked to simplex; Biosynthesis; Dragon tree leaf extract; Gold nanoparticles; Ageing extract
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2019.123744

A process for the synthesis of AuNPs from aged Dracaena Draco L leaf extract. [Display omitted] The biosynthesis of ultra-small gold nanoparticles (AuNPs) with very narrow size distribution and stable dispersion through an aqueous drago (Dracaena draco L) aged leaf extract used as a non-toxic reducing and stabilizing agent has been achieved. The gold nanoparticles obtained in this way, have a size in the range 0.9–2.8 nm and an average size of 1.63 ± 0.35 nm. The ageing of the extract was fundamental to the success of the synthesis as it reduced the size of the nanoparticles by half and improved their stability. This natural ageing process, which to the best of our knowledge is described for the first time in biosynthesis, was accomplished by incubating the extract at ambient temperature without incorporating chemicals during 14 days. The optimized synthesis process took only 15 min at 60 °C. The morphology and crystalline phase of the AuNPs were characterized by transmission electron microscopy. The composition of the nanoparticles was evaluated by electron diffraction and X-ray energy dispersive spectroscopy. The stability of the AuNPs was estimated by a combination of dynamic light scattering and UV–vis spectroscopy. Fourier transform infrared spectroscopy (FTIR) and total phenolic content data, evidenced the evolution of the extract during the ageing process and the presence of biomolecules that could be responsible for reducing Au3+ and capping the AuNPs. A mechanism for the formation of the AuNPs and a hypothesis concerning the types of organic molecules involved in this process are also proposed.