Investigating the Production of Antimicrobial Nanoparticles by Chlorella vulgaris and the Link to Its Loss of Viability

Abstract

Chlorella vulgaris from Al-Ahsa, KSA was proved to be an active silver and gold nanoparticle producer. Nanogold and nanosilver particles were characterized using UV-visible spectroscopy, Fourier-transform infrared spectroscopy, and scanning electronmicroscopy. Both nanoparticles were used in the antimicrobial bioassay. The two nanoparticles showed antibacterial activities, with the silver nanoparticles being the most effective. To investigate the argumentative nature of their biosynthesis (i.e., whether it is a biotic or abiotic process), we isolated total ribonucleic acid RNA as an indicator of vitality. RNA was completely absent in samples taken after one week of incubation with silver nitrate and even after one or two days. However, successful extraction was only achievable in samples taken after incubation for one and four hours with silver nitrate. Most importantly, the gel image showed recognizable shearing of the nucleic acid after 4 h as compared to the control. An assumption can be drawn that the synthesis of nanoparticles may start biotically by the action of enzyme(s) and abiotically by action of reducing entities. Nonetheless, with prolonged incubation, excessive nanoparticle accumulation can be deadly. Hence, their synthesis continues abiotically. From the RNA banding profile, we suggest that nanosilver production starts both biotically and abiotically in the first few hours of incubation and then continues abiotically. Nanosilver particles proved to have more of an antimicrobial impact than nanogold and hence are recommended for different applications as antibacterial agents.

New formula of the green synthesised Au@Ag core@shell nanoparticles using propolis extract presented high antibacterial and anticancer activity

“…Several studies have reported the antibacterial activity of AgNPs, and AuNPs (Kuppusamy et al 2017 ; Beldjilali et al 2020 ; Herbin et al 2022 ). Moreover, recent studies supported that AgNPs have higher activity than AuNPs (Liu et al 2016 ; Aldayel et al 2022 ; Beck et al 2022 ), which can be explained by the different functional groups attributed to both nanoparticles upon the biosynthesis (Li et al 2018 ). Moreover, the alloy of the bi-metallic Au-AgNPs shows various promising applications in different fields, as many studies reported its higher reactivity compared to each of the nanoparticles (Emam et al 2017 ; Fang et al 2019 ; Ha Pham et al 2021 ).…”

Microalgae as a potential natural source for the green synthesis of nanoparticles

“…In other studies, (just to mention a few of the works as examples) Soleimani and Habibi-Pirkoohi, 2017, Morowyat et al, 2023, and Aldayel et al, 2022 10,77,94 reported that AgNPs, ZnONPs, and AuNPs/AgNPs green-synthesized from C. vulgaris had antibacterial activity against Staphylococcus aureus, S. aureus/Enterococcus, E. coli/S. aureus, and Streptococcus sp., respectively.…”

“…These potentialities qualify microalgae as a promising source of raw material for the synthesis of various NPs. 76,77 In summary, microalgae often have remarkable advantages in terms of production efficiency, compositional uniformity, and environmental adaptability compared to vascular plants, making them promising candidates for NPs biosynthesis with various fields of application. 5…”

Plant and Microbial Approaches as Green Methods for the Synthesis of Nanomaterials: Synthesis, Applications, and Future Perspectives

“…37-2-1), have also been shown to have antibacterial activity. Moreover, Chlorella vulgaris, as a nanofactory microalgae, was used for the synthesis of Ag and Au nanoparticles [ 75 ]. The two types of nanoparticles showed antibacterial activity toward Staphylococcus aureus , Streptococcus spp., and Escherichia coli.…”