Keywords: Silver nanoparticles (AgNPs); Cosmos caudatus; biomimetic synthesis; aqueous extract; methanol extract

Abstract

Nanotechnology has been developed because of its tremendous potential for industries and silver nanoparticles (AgNPs) is known for its valuable particles. This is mainly due to its inert character as an inorganic metal element that has strong antibacterial effects and can be synthesized using plant extracts. Basically, Cosmos caudatus is the chosen plant but it has less exposed in the field of nanotechnology. There are a few approaches used to synthesize AgNPs including the physical method, the chemical method, and the biomimetic method. The biomimetic method is the best approach as it is environmentally-friendly and gives off non-toxic effects. This research aims for the characterization of AgNPs using the aqueous extract and methanol extract of C. caudatus. One of the objectives is to obtain a crude extract of C. caudatus by using the cold extraction method before continuing to synthesize the AgNPs from the extracted sample by treating it with AgNO3. This research is aimed at determining the phytochemicals in C. caudatus extract that may contributes to the formations of AgNPs. In regards to the morphology characterization of the AgNPs, the synthesized AgNPs were observed for any peaks generated by UV-Vis spectroscopy and FTIR. There are reportedly five major phytochemicals in aqueous extract including tannins, alkaloids, flavonoids, phenols, and terpenoids, while there are four major phytochemicals in methanol extract such as tannins, proteins, alkaloids, and phenols. The formation of AgNPs aqueous extract and AgNPs methanol extract was confirmed by UV-Vis absorption peaks at approximately 411 nm and 410 nm, respectively. Meanwhile, the FTIR results indicates the presence of O-H, C-H, C=C bands that may contribute to the phenolics and the flavonoids compounds in the extract. In conclusion, the AgNPs have been successfully synthesized through the biomimetic process by reducing silver nitrate with several important phytochemicals of Cosmos caudatus aqueous and methanol extract. The potential of AgNPs may pave the way for a new range of pharmacological properties especially for antibacterial and antivirus properties.