Sargassum Influx on the Mexican Coast: A Source for Synthesizing Silver Nanoparticles with Catalytic and Antibacterial Properties

Beatriz Liliana España-Sánchez,Angel Ramon Hernandez-Martinez,Rodolfo Silva,Rodrigo Esparza,Jose Luis López-Miranda,Miriam Estévez,Marlen Alexis González-Reyna

doi:10.3390/app11104638

Abstract

This work reports, for the first time, the synthesis of silver nanoparticles using extracts of the species of Sargassum natans and Sargassum fluitans (AgNPs-S). Their antibacterial and catalytic properties are compared with silver nanoparticles obtained by chemical synthesis (AgNPs-C). The characterization of AgNPs-S and AgNPs-C was carried out using ultraviolet–visible spectroscopy (UV–Vis), dynamic light scattering (DLS), zeta potential, a scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis. The synthesis of silver nanoparticles using Sargassum extract was optimized through varying experimental parameters, such as the type of solvent used to prepare the extract, the volume of the extract, and the pH of the system. The most efficient sample (AgNPs-S) was prepared with a water–ethanol-based extract, using a 3:1 volumetric ratio of extract: a precursor salt with the addition of 1 mL of NaOH pH = 14. The AgNPs-C were spherical in shape, with an average particle size of 11.55 nm, while the AgNPs-S were polyhedral shaped, with an average particle size of 26.39 nm. The synthesized AgNPs-S were found to have significantly higher catalytic activity for the degradation of methylene blue and more effective antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa than AgNPs-C.

Highlights

The surface waters of the Caribbean and western central Atlantic were considered oligotrophic, with low surface chlorophyll, and occasionally described as “ocean deserts” [1]
Some important parameters can be considered in the green synthesis process to obtain highly stable nanoparticles, such as the selection of the best plant and the optimization of the reaction conditions: for example, light, temperature, pH, mixing speed, concentration, etc
In this paper we report the use of Sargassum extract to synthesize silver nanoparticles

Summary

Introduction

The surface waters of the Caribbean and western central Atlantic were considered oligotrophic, with low surface chlorophyll, and occasionally described as “ocean deserts” [1]. The following year, the same unusual case was seen, and since 2011, huge amounts of Sargassum have been reported intermittently in what was until known as the Atlantic Sargassum belt [4,5]. The unusual is becoming the usual, as aggregations of Sargassum have washed up on the shores around the Caribbean, with a maximum of over 20 million metric tons in June 2018 [4,6]. Chavez et al [7] reported for the Mexican Caribbean yearly averages of 3.2 × 103 and

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