Comparative Study on Antibacterial Activity of MgO Nanoparticles Synthesized from Lawsonia inermis Leaves Extract and Chemical Methods

A review on the green synthesis of metal (Ag, Cu, and Au) and metal oxide (ZnO, MgO, Co3O4, and TiO2) nanoparticles using plant extracts for developing antimicrobial properties

Green synthesis (GS) is a vital method for producing metal nanoparticles with antimicrobial properties. Unlike traditional methods, green synthesis utilizes natural substances, such as plant extracts, microorganisms, etc., to create nanoparticles. This eco-friendly approach results in non-toxic and biocompatible nanoparticles with superior antimicrobial activity. This paper reviews the prospects of green synthesis of metal nanoparticles of silver (Ag), copper (Cu), gold (Au) and metal oxide nanoparticles of zinc (ZnO), magnesium (MgO), cobalt (Co3O4), and titanium (TiO2) using plant extracts from tissues of leaves, barks, roots, etc., antibacterial mechanisms of metal and metal oxide nanoparticles, and obstacles and factors that need to be considered to overcome the limitations of the green synthesis process. The clean surfaces and minimal chemical residues of these nanoparticles contribute to their effectiveness. Certain metals exhibit enhanced antibacterial properties only in GS methods due to the presence of bioactive compounds from natural reducing agents such as Au and MgO. GS improves TiO2 antibacterial properties under visible light, while it would be impossible without UV activation. These nanoparticles have important antimicrobial properties for treating microbial infections and combating antibiotic resistance against bacteria, fungi, and viruses by disrupting microbial membranes, generating ROS, and interfering with DNA and protein synthesis. Nanoscale size and large surface area make them critical for developing advanced antimicrobial treatments. They are effective antibacterial agents for treating infections, suitable in water purification systems, and fostering innovation by creating green, economically viable antibacterial materials. Therefore, green synthesis of metal and metal oxide nanoparticles for antibacterial agents supports several United Nations Sustainable Development Goals (SDGs), including health improvement, sustainability, and innovation.

Assessment of the bioactivity of bioinspired magnesium oxide nanoparticles from the Azadirachta indica extract

Azadirachta indica (neem) extract was used to biologically synthesize magnesium oxide nanoparticles (MgO NPs). The synthesized NPs were characterized using X-ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR), and UV-vis spectroscopy. Antioxidant, anticancer, antibacterial, antidiabetic, and anti-inflammatory activities were analyzed for the synthesized MgO NPs and neem extract. The obtained results confirmed the synthesis of spherical magnesium oxide nanoparticles with an average particle size of 23 nm using XRD. The samples exhibited good thermal stability and high stability in biological media. Compared to the neem extract and chemically synthesized magnesium oxide nanoparticles, the bioinspired magnesium oxide nanoparticles showed considerable free radical scavenging activity, with an IC50 value of 69.03 μg/mL. In addition, they reflected high selectivity to liver hepatic cancer cells with an IC50 value of 94.85 μg/mL without inducing any damage to human umbilical vein endothelial cells. The antibacterial activity of the bioinspired magnesium oxide nanoparticles demonstrated comparable effectiveness in treating both Gram-positive and Gram-negative bacterial strains. Furthermore, the produced bioinspired magnesium oxide nanoparticles showed a high percentage of inhibition for both α-amylase and α-glucosidase enzymes with an IC50 value of 61. 53 and 50.6 μg/mL, respectively. In addition, the bioinspired magnesium oxide nanoparticles also showed a higher denaturation inhibition percentage with an IC50 value of 6.66 μg/mL, indicating strong anti-inflammatory action. These enhanced abilities usher in a new bioinspired magnesium oxide nanoparticle bio-application era. Consequently, further in vivo studies are needed to assess the kinetic properties of these nanoparticles.

Investigating the effect of acidic and basic precipitation on the antibacterial activity of ZnO nanoparticles against Gram-negative and Gram-positive bacteria

In the present work, acidic (direct) and basic precipitation (indirect) methods were used to demonstrate the influence of the mode of precipitation on the structural properties of ZnO nanoparticles (NPs). Four samples of ZnO nanoparticles were prepared, two samples via each mode of precipitation. DZOa and IZOa were the aged samples prepared via acidic and basic precipitation methods, and DZOwa and IZOwa were processed without aging. Both precipitation processes were carried out without using any surfactant reagents. Zinc hydroxide precipitate, which was formed during the basic precipitation method, could be critical in deciding the properties of ZnO NPs, unlike zinc hydroxide formed during acidic precipitation. Aging of zinc hydroxide, synthesised by basic precipitation method for 48 hours was found to be an added advantage in controlling the properties of ZnO NPs. The influence of the mode of precipitation on the structural properties and antibacterial activity of ZnO NPs against Gram-positive and Gram-negative bacterial strains was tested. The antibacterial activity of all four ZnO NPs was analysed via zone of inhibition measurements at a concentration dose of 200 μg ml-1. IZOa nanoparticles prepared using the basic precipitation method showed a higher antibacterial activity against three Gram-negative and one Gram-positive strains, namely, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli. DZOa nanoparticles synthesized through acidic precipitation showed relatively high antibacterial activity against Salmonella typhimurium, a Gram-negative strain. ZnO NPs prepared without aging, IZOwa and DZOwa, showed a higher antibacterial activity against E. coli and Bacillus sp. strains, respectively. All ZnO NPs were characterized via UV-visible, FTIR, XRD, and HRSEM techniques.

A critical review on the bio-mediated green synthesis and multiple applications of magnesium oxide nanoparticles

Nowadays, advancements in nanotechnology have efficiently solved many global problems, such as environmental pollution, climate change, and infectious diseases. Nano-scaled materials have played a central role in this evolution. Chemical synthesis of nanomaterials, however, required hazardous chemicals, unsafe, eco-unfriendly, and cost-ineffective, calling for green synthesis methods. Here, we review the green synthesis of MgO nanoparticles and their applications in biochemical, environmental remediation, catalysis, and energy production. Green MgO nanoparticles can be safely produced using biomolecules extracted from plants, fungus, bacteria, algae, and lichens. They exhibited fascinating and unique properties in morphology, surface area, particle size, and stabilization. Green MgO nanoparticles served as excellent antimicrobial agents, adsorbents, colorimetric sensors, and had enormous potential in biomedical therapies against cancers, oxidants, diseases, and the sensing detection of dopamine. In addition, green MgO nanoparticles are of great interests in plant pathogens, phytoremediation, plant cell and organ culture, and seed germination in the agricultural sector. This review also highlighted recent advances in using green MgO nanoparticles as nanocatalysts, nano-fertilizers, and nano-pesticides. Thanks to many emerging applications, green MgO nanoparticles can become a promising platform for future studies.

New Green Approaches in Nanoparticles Synthesis: An Overview

Nanotechnology is constantly expanding, with nanomaterials being more and more used in common commercial products that define our modern life. Among all types of nanomaterials, nanoparticles (NPs) occupy an important place, considering the great amount that is produced nowadays and the diversity of their applications. Conventional techniques applied to synthesize NPs have some issues that impede them from being appreciated as safe for the environment and health. The alternative to these might be the use of living organisms or biological extracts that can be involved in the green approach synthesis of NPs, a process that is free of harmful chemicals, cost-effective and a low energy consumer. Several factors, including biological reducing agent concentration, initial precursor salt concentration, agitation, reaction time, pH, temperature and light, can influence the characteristics of biologically synthesized NPs. The interdependence between these reaction parameters was not explored, being the main impediment in the implementation of the biological method on an industrial scale. Our aim is to present a brief review that focuses on the current knowledge regarding how the aforementioned factors can control the size and shape of green-synthesized NPs. We also provide an overview of the biomolecules that were found to be suitable for NP synthesis. This work is meant to be a support for researchers who intend to develop new green approaches for the synthesis of NPs.