Efficacy of silver nanoparticles mediated by Jania rubens and Sargassum dentifolium macroalgae; Characterization and biomedical applications

Abstract

Jania rubens and Sargassum dentifolium aqueous extracts were used as a reducing agent for the synthesis of silver nanoparticles (Ag-NPs). The prepared Ag-NPs have two plasmon absorption bands at 440 nm and 420 nm, with a direct band gap 2.25 eV and 2.38 eV for Ag-NPs/J. rubens and Ag-NPs/S. dentifolium respectively. From the FTIR results, the reduction has mostly been carried out by CN, hydroxyl or sulfated polysaccharides groups present in J. rubens and S. dentifolium, respectively. TEM images shown that most particles are spherical in shape with no aggregations or debris were detected. The concentration of S. dentifolium/NPs showed approximately 2-fold than J. Rubens/NPs (470 and 240 × 103 NPs/ml) and an average particle size of 113 and 155 nm, respectively. A high repulsive and attractive forces between each nanoparticle were confirmed with an average zeta potential −24.7 and −28.2 mV for J. rubens/NPs and S. dentifolium/NPs, respectively. On the other hand, Ag-NPs concentrations of 104–105/ml were sufficient for killing Salmonella typhimurium, Enterobacter aerogenes, Pseudomonas aeruginosa, Escherichia coli, and the Gram-positive methicillin-resistant Staphylococcus aureus. Generally, both NPs showed reproducible, effective antibacterial activity with no significant differences between values of MIC and/or MBC for the two NPs against the tested pathogens. The results on biofilm formation implicate significant inhibition at the beginning of the adherence stage at various concentrations of Ag-NPs tested. Consequently, silver nanoparticles could be an effective antimicrobial agent without cause microbial resistance even after long-term usage.