Search Results (94)

The contamination of water bodies by industrial dyes poses a significant environmental challenge on a global scale. Conventional wastewater treatment methods often suffer from limitations related to high cost, limited efficiency, and potential secondary environmental impacts. Recent advances in photocatalytic technologies have highlighted the potential of metal sulfide-based photocatalysts, particularly those synthesized through environmentally friendly, plant-mediated approaches, as promising alternatives for efficient and sustainable dye degradation. However, despite their promising potential, metal sulfide photocatalysts often suffer from limitations such as photocorrosion, low stability under irradiation, and rapid recombination of charge carriers, which restrict their long-term applicability. In light of these challenges, this review provides a comprehensive examination of the physicochemical characteristics, synthetic strategies, and photocatalytic applications of metal sulfides. Particular emphasis is placed on green synthesis routes employing plant-derived extracts, which offer environmentally benign and sustainable alternatives to conventional methods. Moreover, the review elucidates various modification approaches, most notably, the formation of heterostructures, as viable strategies to enhance photocatalytic efficiency and mitigate the aforementioned drawbacks. The green synthesis of metal sulfides, aligned with the principles of green chemistry, offers a promising route toward the development of sustainable and environmentally friendly water treatment technologies. Full article

The green synthesis of zinc oxide nanoparticles (ZnO NPs) using Artemisia absinthium L. extract has gained considerable attention due to its eco-friendly approach and potential applications in food science. This study investigates the synthesis and characterization of Artemisia-mediated ZnO NPs, focusing on their physicochemical properties. The nanoparticles were characterized using ultraviolet–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), and energy dispersive X-ray spectroscopy (EDX). Successful synthesis was achieved through a co-precipitation method, resulting in an average particle size of 36.6 nm. The presence of polyphenols and flavonoids in A. absinthium L. extract acted as both a reducing agent and stabilizer for the nanoparticles. The physicochemical characterization revealed strong absorption peaks indicative of ZnO, confirming successful nanoparticle formation. In addition to the structural findings, this study presents novel insights by demonstrating that Artemisia-mediated ZnO NPs possess significantly enhanced antimicrobial activity compared to both pure ZnO NPs and the plant extract alone. The biosynthesized nanoparticles exhibited notably lower minimum inhibitory concentration (MIC) and minimum bactericidal/fungicidal concentration (MBC/MFC) values against Staphylococcus aureus, Escherichia coli, and Candida albicans, suggesting a strong synergistic effect between ZnO and the phytochemicals of A. absinthium L. Thus, the study confirms and quantifies the superior antibacterial potential of Artemisia-derived ZnO NPs, offering promising implications for food, biomedical and pharmaceutical applications. Full article

Green synthesis of silver nanoparticles (AgNPs) using plant extracts has emerged as a sustainable and eco-friendly alternative to conventional physical and chemical methods. This review provides a comprehensive overview of plant-mediated synthesis routes, emphasizing the influence of phytochemicals on nanoparticle formation, morphology, and stability. The physicochemical properties of AgNPs, such as size, shape, and surface characteristics, are critically examined in relation to synthesis parameters, summarizing the plant species employed and associated reaction conditions. The wide-ranging applications of plant-based AgNPs are explored, including antimicrobial, agricultural, environmental, industrial, and biomedical uses, such as drug delivery and wound healing. The section is supported with recent application-specific studies to their corresponding nanoparticle properties, highlighting the relationship between structure and function. Finally, this review discusses current challenges, particularly potential toxicity considerations, and outlines future perspectives for standardization, mechanistic understanding, and translational potential in wide-ranging applications. Full article

Nanotechnology is an emerging field in science that exhibits significant promise in the synthesis of nanomaterials for diverse applications. Traditionally, these nanomaterials were manufactured using hazardous and labor-intensive physical and chemical processes. Nevertheless, in recent years, researchers have developed safer, more scalable, and environmentally friendly methods for green synthesis. The problem addressed in this study is the need for an environmentally friendly and efficient synthesis process for titanium dioxide nanoparticles (TiO₂ NPs) with enhanced properties. The aim of this work is to describe the synthesis of TiO₂ NPs with various plant extracts using a green approach and to evaluate the physicochemical characteristics and potential applications of the resulting nanoparticles. This study focuses on understanding how the integration of plant extracts influences the properties of TiO₂ NPs, particularly in terms of their structural, optical, and functional characteristics. The novelty lies in the use of plant extracts as bio-reductants and capping agents, which not only provides a safer and more sustainable synthesis method but also enhances the functional properties of TiO₂ NPs. This green synthesis approach reduces the use of harmful chemicals, making the process more environmentally friendly and economically viable, with potential applications in photocatalysis, antibacterial, and antioxidant activities. The TiO₂ NPs possess diverse functionalities, including photocatalysis, antibacterial properties, and antioxidant properties. The initial precursor, such as a metal salt, undergoes transformation into the desired nanoparticles through the actions of plants exactly. Bio-reduction and capping processes are carried out by secondary metabolites found in bacteria and plants. The results demonstrated that the plant extract-mediated TiO₂ NPs exhibited enhanced photocatalytic activity, superior antibacterial effects, and higher antioxidant potential compared to chemically synthesized TiO₂ NPs. This highlights the potential of green synthesis methods in producing nanomaterials with improved functional properties for a wide range of applications. Full article

An aqueous leaf extract of Egeria densa was used to green-synthesize iron (II) and iron (III) oxide nanoparticles from ferrous sulphate and ferric chloride, respectively. The successful green synthesis of the nanoparticles was confirmed through UV–visible spectroscopy, and the colour of the mixtures changed from light-yellow to green-black and reddish-brown for FeO–NPs and Fe₂O₃–NPs, respectively. The morphological characteristics of the nanoparticles were determined using an X-ray diffractometer (XRD), a Fourier transform infrared spectrophotometer (FTIR), a transmission electron microscope (TEM), and energy-dispersive X-ray spectroscopy (EDX). The UV–Vis spectrum of the FeO–NPs showed a sharp peak at 290 nm due to the surface plasmon resonance, while that of the Fe₂O₃–NPs showed a sharp peak at 300 nm. TEM analysis revealed that the FeO–NPs were oval to hexagonal in shape and were clustered together with an average size of 18.49 nm, while the Fe₂O₃-NPs were also oval to hexagonal in shape, but some were irregularly shaped, and they clustered together with an average size of 27.96 nm. EDX analysis showed the presence of elemental iron and oxygen in both types of nanoparticles, indicating that these nanoparticles were essentially present in oxide form. The XRD patterns of both the FeO–NPs and Fe₂O₃–NPs depicted that the nanoparticles produced were crystalline in nature and exhibited the rhombohedral crystal structure of hematite. The FT-IR spectra revealed that phenolic compounds were present on the surface of the nanoparticles and were responsible for reducing the iron salts into FeO–NPs and Fe₂O₃–NPs. Conclusively, this work demonstrated for the first time the ability of Elodea aqueous extract to synthesize iron-based nanoparticles from both iron (II) and iron (III) salts, highlighting its versatility as a green reducing and stabilizing agent. The dual-path synthesis approach provides new insights into the influence of the precursor oxidation state on nanoparticle formation, thereby expanding our understanding of plant-mediated nanoparticle production and offering a sustainable route for the fabrication of diverse iron oxide nanostructures. Furthermore, it provides a simple, cost-effective, and environmentally friendly method for the synthesis of the FeO–NPs and Fe₂O₃–NPs using Egeria densa. Full article

Background/Objectives: This study reports the green synthesis, optimization, characterization, and multifunctional evaluation of silver nanoparticles (AgNPs) using an ethanolic Aronia melanocarpa berry extract. The objective was to establish optimal synthesis conditions; assess the in vitro stability; and evaluate the antioxidant, photocatalytic, and photoprotective activities. Methods: The cytogenotoxic effects of the AgNPs were evaluated on Triticum aestivum roots. The AgNPs were synthesized via bioreduction using an ethanolic extract of A. melanocarpa under varied pH, AgNO₃ concentration, extract/AgNO₃ ratio, temperature, and stirring time, with optimization guided by UV–Vis spectral analysis. The AgNPs were further characterized by FTIR, DLS, TEM, and EDX. In vitro stability was evaluated over six months in different dispersion media (ultrapure water; 5% NaCl; and PBS at pH 6, 7, and 8). Biological assessments included antioxidant assays (lipoxygenase inhibition, DPPH radical scavenging, metal chelation, and hydroxyl radical scavenging), photocatalytic dye degradation, and SPF determination. Results: Optimal synthesis was achieved at pH 8, 3 mM AgNO₃, extract/AgNO₃ ratio of 1:9, 40 °C, and 240 min stirring. The AgNPs were spherical (TEM), well dispersed (PDI = 0.32), and highly stable (zeta potential = −40.71 mV). PBS pH 6 and 7 ensured the best long-term colloidal stability. The AgNPs displayed strong dose-dependent antioxidant activity, with superior lipoxygenase inhibition (EC₅₀ = 18.29 µg/mL) and the effective photocatalytic degradation of dyes under sunlight. Photoprotective properties were confirmed through UV absorption analysis. The AgNPs showed a strong antimitotic effect on wheat root cells. Conclusions: The study demonstrates that A. melanocarpa-mediated AgNPs are stable, biologically active, and suitable for potential biomedical, cosmetic, and environmental applications, reinforcing the relevance of plant-based nanotechnology. Full article

This study investigates the catalytic potential of silver nanoparticles (AgNPs) synthesized using aqueous Cymbopogon citratus (lemongrass) extract for the degradation of toxic textile dyes, offering an eco-friendly solution to industrial wastewater treatment. The green-synthesized AgNPs demonstrated remarkable degradation efficiency (>94%) for multiple dyes, such as rhodamine B, methyl red, methyl orange, methylene blue, eosin yellow, and Eriochrome black T, in the presence of sodium borohydride. Optimization studies employing a one-factor-at-a-time approach revealed the critical influence of AgNPs and reductant concentration, temperature, and pH. Kinetic analysis confirmed pseudo-first-order degradation behavior. Reactive species scavenging experiments established that hydroxyl radicals and holes played dominant roles in the degradation mechanism. Notably, the AgNPs retained catalytic activity across eight reuse cycles with negligible performance loss, demonstrating strong potential for repeated application. Comparative analysis with data from the literature highlights the superior performance of C. citratus-derived AgNPs in terms of reaction rate and efficiency. This work underscores the value of plant-extract-mediated AgNPs synthesis not only for its environmental compatibility but also for its catalytic effectiveness. The study advances the practical applicability of green nanotechnology in wastewater remediation and supports its integration into sustainable industrial practices. Full article

The banana weevil (Cosmopolites sordidus) is a significant pest that reduces banana yields and can result in plant mortality. (2R,5S)-theaspirane, a kairomone from senesced banana leaves, is one of the natural banana volatiles, aiding weevil attraction. A rapid and cost-effective synthesis of (2R,5S)-theaspirane was developed utilizing microwave-assisted conditions and the principles of green chemistry. The process comprised five steps, beginning with the reduction of dihydro-β-ionone, followed by lipase-mediated kinetic resolution to attain high enantiomeric excess. Microwave-assisted heating significantly reduced reaction times. Optimized cyclization with the minimum quantities of selenium dioxide oxidation was employed. The final diastereomers were separated by chromatography, yielding compounds which exceeded 99% enantiomeric purity. Full article

Nanoparticles are small structures that differ in terms of their shape and composition; their high surface-to-volume ratio is responsible for their unique properties that make them perfect mediators for the delivery of substances. Nanoparticles do not only include metallic spheres but also complex polysaccharides capsule viruses or bacterial protein complexes (which can be considered bionanoparticles), which are 1–100 nm in size. Although nanoparticles are most widely studied from medical perspectives, their potential applications are almost limitless. One such promising use of functional nanoparticles is for plant protection against diseases. Although the precise use of nanoparticles decreases the need for the use of other chemical compounds, thanks to their increased product stability and delivery to a target site, the production of nanoparticles is often burdened by large quantities of toxic wastes. This problem can be limited if we apply the bioreactor green synthesis method, which includes the production of nanoparticles with the use of microorganisms. Bacteria can produce nanoparticles internally, externally, by only producing metabolites used for nanoparticle production directly, e.g., polysaccharides or surfactants, or indirectly as reducing agents for metal nanoparticle production. Regardless of the source of the nanoparticles, they can be widely used in processes from plant disease/pathogen detection to disease suppression. The endless variety of materials for nanoparticle production and the possible modifications that nanoparticles can be subjected to makes it impossible to predict how their structures will be used in the future. Nevertheless, in this study, we would like to turn attention to the fact that although nanoparticles are viewed as synthetic structures, they are ever-present in the microbial world and play an important part in intermicrobial interactions. As nanoparticle usefulness has been tested over years of co-evolution, it may be useful to look for potential future directions for this fascinating technology. Full article

MYB (myeloblastosis) is one of the most abundant transcription factors in plants which regulates various biological processes. The molecular characteristics and function of R2R3-MYB transcription factors in amaranth remain unclear. In this study, 73 R2R3-MYB members were identified from the amaranth genome database and we further analyzed their chromosome position, conserved motifs, physiological and biochemical features, collinearity relationships, gene structure, phylogeny and cis-acting element. Based on the phylogenetic and expression pattern analysis, 14 candidate R2R3-MYB genes might be involved in the betalain synthesis. Amongst the 14 candidate R2R3-MYB genes, the expression level of AtrMYB72 was higher in ‘Suxian No.1’ than ‘Suxian No.2’, and also higher in the red section than in the green section of the same leaf in Amaranthus. The overexpression vector pCambia1301-AtrMYB72-GUS and VIGS (virus-induced gene silencing) vector pTRV2- AtrMYB72 were transferred into leaves of ‘Suxian No.1’ via an Agrobacterium-mediated method. The results showed that AtrMYB72 overexpression could promote betalain synthesis. A yeast one-hybrid assay and dual luciferase reporter gene assay demonstrated that AtrMYB72 could bind to the AtrCYP76AD1 promoter to promote betalain synthesis. These results indicated that AtrMYB72 promoted betalain biosynthesis in amaranth by activating the AtrCYP76AD1 transcription. Our results could provide new insights into the betalain biosynthesis in amaranth. Full article

This research achieved the successful synthesis of zinc oxide (ZnO) NPs through an eco-friendly method, utilizing the leaf extract of Leonotis ocymifolia (L.O.). This innovative approach not only highlights the potential of green synthesis but also underscores the effectiveness of natural resources in nanoparticle production. The influence of annealing temperature on the properties and performance of the synthesized ZnO NPs was evaluated by varying the annealing temperatures as follows: unannealed (000), 350 °C (350), 550 °C (550), and 750 °C (750). The XRD analysis of L.O-mediated ZnO NPs confirmed the synthesis of highly crystalline wurtzite-structured ZnO NPs, with calculated average crystallite sizes that ranged between 13.8 and 20.4 nm. The UV–Vis spectra revealed a single strong absorption peak ranging from 354 to 375 nm, and the absorption peaks red-shifted with an increase in annealing temperature. The SEM micrographs showed that annealing temperature had an effect on the morphology, particle size, and distribution, with the average particle of 53.7–66.3 nm. The BET analysis revealed that the surface area of the prepared ZnO NPs was between 31.6 and 13.2 m²/g. In addition to its significant impact on the characteristics of the L.O-mediated, annealing temperature notably boosts the L.O-mediated capacity to photodegrade Methylene blue (MB) dye. Moreover, it exhibited significant antibacterial efficacy against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The photodegradation studies under UV irradiation and in 180 min revealed 750 (71.1%) had the highest degradation efficiency compared to 000, 350, and 550. The antibacterial tests showed that 000 had greater antibacterial efficacy than 350, 550, and 750. The results from this work suggest that annealing temperature had a significant effect on the structural, morphological, and optical properties and performance of L.O-mediated ZnO NPs. Full article

This work presents a green synthesis route, which utilises extracts from an indigenous plant in South Africa, eastern and southern Africa that is understudied and underutilised, for preparing zinc oxide nanoparticles (ZnO NPs). This study involved optimisation of the green synthesis method using Leonotis ocymifolia (L.O.) extracts and performing comparative studies on the effects of using different zinc (Zn) salt precursors; zinc sulphate heptahydrate (Z001) and zinc acetate dihydrate (Z002) to synthesise the ZnO NPs. The comparative studies also compared the L.O-mediated ZnO NPs and chemical-mediated ZnO NPs (Z003). The as-prepared ZnO NPs were tested for their effectiveness in the photodegradation of methylene blue (MB) dye. Furthermore, antibacterial studies were conducted using the agar well diffusion method on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria. The structural, morphological, and optical characteristics of the synthesised ZnO NPs were analysed using XRD, FTIR, SEM, EDS, DRS, and BET techniques. The XRD results indicated that the L.O-mediated ZnO NPs had smaller crystallite sizes (18.24–19.32 nm) than their chemically synthesised counterparts (21.50 nm). FTIR confirmed the presence of biomolecules on the surface of the L.O-mediated NPs, and DRS analysis revealed bandgap energies between 3.07 and 3.18 eV. The EDS results confirmed the chemical composition of the synthesised ZnO NPs, which were made up of Zn and O atoms. Photocatalytic studies demonstrated that the L.O-mediated ZnO NPs (Z001) exhibited a superior degradation efficiency of the MB dye (89.81%) compared to chemically synthesised ZnO NPs (56.13%) under ultraviolet (UV) light for 240 min. Antibacterial tests showed that L.O-mediated ZnO NPs were more effective against S. aureus than E. coli. The enhanced photocatalytic and antibacterial properties of L.O-mediated ZnO NPs highlight their potential for environmental remediation and antimicrobial applications, thus supporting sustainable development goals. Full article

Antioxidants of plant extract play an important role in the phytosynthesis of silver nanoparticles (phyto-AgNPs), providing the reduction of silver ions and capping and stabilization of nanoparticles. Despite the current progress in the studies of phytosynthesis, there is no approach to the selection of plant extract for obtaining phyto-AgNPs with desired properties. This work shows that antioxidant activity (AOA) of plant extracts is a key parameter for targeted phytosynthesis. In support of this fact, the synthesis of phyto-AgNPs was carried out using extracts of four plants with different AOA, increasing in the order Ribes uva-crispa < Lonicera caerulea < Fragaria vesca < Hippophae rhamnoides. Phyto-AgNPs have been characterized using Fourier-transform infrared spectroscopy, transmission electron microscopy, energy-dispersive X-ray spectroscopy, selected area electron diffraction technique, ultraviolet–visible spectroscopy, electrochemical impedance spectroscopy and cyclic voltammetry. It was established that the change in the AOA of the plant extract is accompanied by a size-dependent change in the optical and electrochemical properties of phyto-AgNPs. In particular, an increase in the extract AOA leads to the formation of smaller phyto-AgNPs with higher electrochemical activity and low charge transfer resistance. A “blue shift” and an increase in the plasmon resonance band of silver sols are observed with an increase in the extract AOA. The obtained regularities prove the existence of the “AOA–size–properties” triad, which can be used for controlled phytosynthesis and prediction of phyto-AgNPs’ properties. Full article

Nanotechnology has gained popularity in recent years due to its wide-ranging applications within the scientific community. The three main methods for synthesizing nanoparticles are physical, chemical, and biological. However, the adverse effects associated with physical and chemical methods have led to a growing interest in biological methods. Interestingly, green synthesis using plants has gained prominence in developing new treatments for bacterial infections. Zinc oxide nanoparticles (ZnO NPs) produced using environmentally friendly methods are more biocompatible and have potential applications as antibacterial agents in the biomedical field. As a result, this review discusses the green synthesis of ZnO NPs, factors influencing optimal synthesis, characterization techniques, and the antibacterial activity of some plant-mediated ZnO NPs. It also provides a comprehensive and analytical exploration of ZnO NP biosynthesis, the role of phytochemical compounds as reducing and stabilizing agents, the mechanism of action of their antibacterial properties and further highlights the challenges and prospects in this innovative research area. Full article

Novel fibrous cellulosic substrates impregnated with meta-polybenzimidazole (PBI)-stabilized carbon nanotubes/zinc oxide with different weight content of ZnO and with the use of dimethylacetamide as dispersant media. The pristine ZnO nanoparticle powder was prepared by plant extract-mediated synthesis using Vaccinium vitis-idaea L. The green synthesized ZnO possesses an average crystallite size of 15 nm. The formation of agglomerates from ZnO NPs with size 250 nm–350 nm in the m-PBI@CNTs/ZnO was determined. The prepared materials were investigated by PXRD analysis, XPS, SEM, EDS, AFM, and TEM in order to establish the phase and surface composition, structure, and morphology of the hybrids. The potential of the synthesized hybrid composites to degrade methylene blue (MB) dye as a model contaminant in aqueous solutions under UV illumination was studied. The photocatalytic results show that in the course of the photocatalytic reaction, the m-PBI@CNTs/ZnO 1:3 photocatalyst leads to the highest degree of degradation of the methylene blue dye (67%) in comparison with the other two studied m-PBI@CNTs/ZnO 1:1 and 1:2 composites (48% and 41%). The antibacterial activity of ZnO nanoparticles and the hybrid CNT materials was evaluated by the RMDA and the dynamic contact method, respectively. The profound antibacterial effect of the m-PBI@CNTs/ZnO hybrids was monitored for 120 h of exposition in dark and UV illumination regimes. The photocatalytic property of ZnO nanoparticles significantly shortens the time for bactericidal action of the composites in both regimes. The m-PBI@CNTs/ZnO 1:2 combination achieved complete elimination of 5.10⁵ CFU/mL E. coli cells after 10 min of UV irradiation. Full article