Green synthesis of the Cu/ZnO nanoparticles mediated by Euphorbia prolifera leaf extract and investigation of their catalytic activity

Exploring the potential of surface-modified alginate beads for catalytic removal of environmental pollutants and hydrogen gas generation

In this study, hydrogel beads were fabricated using alginate (Algt) polymer containing dispersed nickel phthalocyanine (NTC) nanomaterial. The viscous solution of Algt and NTC was poured dropwise into a divalent Ca2+ ions, resulting in the formation of hydrogel beads known as NTC@Algt-BDs. The surface of the NTC@Algt-BDs was further modified by coating them with different types of metal ions, yielding metal-coated M+/NTC@Algt-BDs. The adsorbed metal ions i.e., Cu+2, Ag+, Ni+2, Co+2, and Fe+3 were subsequently reduced to zero-valent metal nanoparticles (M0) by NaBH4. The prepared beads were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Initially, M0/NTC@Algt-BDs were examined for the catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). Among them, Cu0/NTC@Algt-BDs catalyst exhibited the highest reduction rate and therefore, investigated for reduction of different nitrophenols (NPs) and dyes, including 2-nitrophenol (2-NP), 2,6-dinitrophenol (2,6-DNP), methyl orange (MO), potassium ferrocyanide (PFC), congo red (CR), and acridine orange (ArO). The highest reduction rates of 2.019 and 1.394 min-1 were observed for MO and 2-NP, respectively. Furthermore, the fabricated catalysts were employed for the efficient production of H2 gas by NaBH4 methanolysis. Among which the Ag0/NTC@Algt-BDs catalyst showed excellent catalytic production of H2 gas, exhibiting the lowest activation energy (Ea) of 25.169 kJ/mol at ambient temperature. Furthermore, the impact of NaBH4 amount, and catalyst dosage on the reduction of 2-NP and H2 gas production was conducted whereas the effect of temperature on methanolysis of NaBH4 for evolution of H2 gas was studied. The amount of H2 gas was confirmed by GC-TCD system. Additionally, the recyclability of the catalyst was investigated, as it garnered significant research interest.

Phyto-fabricated ZnO nanoparticles for anticancer, photo-antimicrobial effect on carbapenem-resistant/sensitive Pseudomonas aeruginosa and removal of tetracycline

Alternanthera sessilis (AS) leaf extract was used to synthesize zinc oxide nanoparticles (ZnO NPs). Bioanalytical characterization techniques such as X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) confirmed the formation of crystalline ZnO NPs with average sizes of 40 nm. The AS-ZnO NPs antimicrobial activity was analyzed under dark (D) and white light (WL) conditions. The improved antimicrobial activity was observed against Escherichia coli, Staphylococcus aureus and Bacillus subtilis at the minimal inhibitory concentration (MIC) of 125 and 62.5 µg/mL under WL than the D at 125 and 250 µg/mL for E. coli, B. subtilis, and Pseudomonas aeruginosa, respectively. In contrast, the growth of P. aeruginosa and S. aureus was not completely inhibited until 1 mg/mL AS-ZnO NPs under WL and D. Similarly, AS-ZnO NPs displayed a weaker inhibitory effect against carbapenem-sensitive P. aeruginosa (CSPA) and carbapenem-resistant P. aeruginosa (CRPA) strains of PAC023, PAC041 and PAC032, PAC045 under D. Interestingly, the distinct inhibitory effect was recorded against CSPA PAC041 and CRPA PAC032 in which the bacteria growth was inhibited 99.9% at 250, 500 µg/mL under WL. The cytotoxicity results suggested AS-ZnO NPs demonstrated higher toxicity to MCF-7 breast cancer cells than the RAW264.7 macrophage cells. Further, AS-ZnO NPs exhibited higher catalytic potential against tetracycline hydrochloride (TC-H) degradation at 65.6% and 60.8% under WL than the dark at 59.35% and 48.6% within 120 min. Therefore, AS-ZnO NPs can be used to design a photo-improved antimicrobial formulation and environmental catalyst for removing TC-H from wastewater.

Antibacterial and phytotoxicological properties assessment of Momordica charantia extract-based ZnO nanoparticles

BACKGROUND

Utilizing the fruit extract of bitter melon (Momordica charantia), zinc nanoparticles (ZnO-NPs) were synthesized through a green approach, a novel endeavor in current literature. The primary objective was to evaluate the phytotoxic and growth-promoting effects of these ZnO-NPs on wheat, chosen as a test plant. Structural characterization using X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy revealed the hexagonal wurtzite crystal structure of ZnO-NPs and identified spherical M. charantia-produced (MC)-ZnO-NPs ranging in size from 48 to 150 nm.

RESULTS

At a concentration of 2000 mg L-1 , both MC- and raw-ZnO-NPs augmented wheat germination percentages. Furthermore, raw-ZnO-NPs at 4000 mg L-1 demonstrated the highest chlorophyll content. Despite the plant's increased accumulation of MC-ZnO-NPs, no statistically significant toxic effects were observed. The antibacterial efficacy of ZnO-NPs was assessed against Gram-positive and Gram-negative microorganisms. MC-ZnO-NPs exhibited a 67.9% inhibition zone against Escherichia coli at 0.04 mg L-1 , while raw-ZnO-NPs exhibited 75.6% inhibition at the same concentration.

CONCLUSION

The study suggests that ZnO-NPs synthesized from M. charantia exhibit both growth-promoting effects on wheat without significant phytotoxicity and potent antibacterial properties, particularly against Escherichia coli. However, further investigations are warranted to comprehensively understand the interactions between ZnO-NPs and plants. Future research should focus on M. charantia, exploring its enhanced effects on plant growth, development and antibacterial attributes. These findings hold promise for potential agricultural applications, emphasizing the need for detailed phytotoxicological assessments of ZnO-NPs. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Current scenario on biogenic synthesis of metal oxide nanocomposites using plant specimens and their application towards treatment of wastewater

Various industries such as textile, leather, and paper mills discharge huge amount of industrial effluents to the environment containing unconsumed dyes and toxic heavy metal ions which are very harmful and carcinogenic in nature. The increase in water pollution is adversely impacting the ecosystems and human health. Now, it has become a great challenge to treat the contaminated water/wastewater. Photocatalysis and adsorption are the two techniques gaining significant attention for the removal of toxic pollutants from wastewater effectively. In this regard, metal oxide-based nanomaterials and their composites have gained profound attention in photocatalytic degradation as well as adsorptive removal of toxic pollutants from water due to their chemical reactivity, higher surface area, regeneration efficiency, ample adsorption sites, intriguing photocatalytic activity, and cost-effectiveness. However, the conventional methods, employed to synthesize these metal oxide nanocomposites, involve the use of toxic chemicals which again produce secondary pollutants. Among all biological materials, the use of plant biomolecules is found to be the most effective way to synthesize stable nanomaterials, as the phytoconstituents of plants act as reducing, capping, and stabilizing agent. It is experimentally proved that bio-based nanocomposites have tremendous potential towards the degradation of environmental pollutants. Thus, there is a great need to work on the synthesis of some novel plant-based metal oxide nanocomposites and their applications in the field of water treatment. This review mainly discusses the metal oxide nanocomposites synthesized using plant specimens and their various applications towards treatment of water/wastewater.

Optically amended biosynthesized crystalline copper-doped ZnO for enhanced antibacterial activity

The emergence and re-emergence of antibiotic-resistant bacteria is a potential threat to treating infectious diseases. This study employed a nanometer-scale green synthesis using an extract of Solanum incanum leaves to obtain nanoparticles (NPs) and nanocomposites (NCs) possessing antibacterial properties. The FESEM-EDS elemental mapping analysis proved the novelty of the green synthesis approach in synthesizing a copper-doped ZnO NCs with good dopant distribution. The crystallinity and ZnO bandgap were adjusted by extrinsic copper doping in the ZnO lattice. The optical property adjustments from 3.04 to 2.97 eV for indirect Kubelka-Munk functions were confirmed from DRS-UV-vis analysis. The dopant inclusion in the host lattice was also confirmed by the angle shift on the XRD pattern analysis relative to single ZnO. In addition to doping, the XRD pattern analysis also showed the development of CuO crystals. The lattice fringe values from HRTEM analysis confirmed the existence of both CuO and ZnO crystals with local heterojunctions. Doping and heterojunctions have crucial values in charge transfer and visible light harvesting behaviour, as proved by the PL analysis. The synergistic effects of the doped NCs showed greater antibacterial activity against both Gram-positive and Gram-negative bacteria as a result of more ROS generation through the bacteria-cell-catalyst interaction and release of metal ions. The antioxidant potential of the doped NCs was found to be higher than that of single NPs, using the 2,2-diphenyl-1-picrylhydrazyl free radical scavenging assay and is expected to impart protective effects to the host cells by scavenging destructive free radicals. Thus, the overall analysis leads to the conclusion that the potentiality of synthesized materials has a future outlook for biological applications, especially in the development of antimicrobials to combat antibiotic-resistant bacteria and microbes.

Recent progress on plant extract-mediated biosynthesis of ZnO-based nanocatalysts for environmental remediation: Challenges and future outlooks

The plant extract mediated green synthesis of nanomaterials has attracts enormous interest due to its cost-effectiveness, greener, and environmentally friendly. It is also considered as an alternative and facile method in which the phytochemicals can be used as a natural capping and reducing agents and helped to produce nanomaterials with high surface area, different sizes, and shapes. One of the materials fabricated using green methods is zinc oxide (ZnO) semiconductor due to its enormous applications in different field areas. In this review, an overview of recent progress on green synthesized ZnO-based catalysts and various modification methods for the purpose of enhancing the catalytic activity of ZnO and the corresponding structural-activity and interactions towards the removal of pollutants are highlighted. Particularly, the plant extract mediated ZnO-based photocatalysts application for the removal of pollutants via photocatalytic degradation, reduction reaction, and adsorption mechanism are demonstrated. Besides, the opportunities, challenges, and future outlooks of ZnO-based materials for environmental remediation with green and sustainable methods are also included. We believe that this review is a timely and comprehensive review on the recent progress related to plant extract mediated ZnO-based nanocatalysts synthesis and applications for environmental remediation.

Eliminating xenobiotics organic compounds from greywater through green synthetic nanoparticles

Xenobiotic Organic Compounds (XOCs) have been widely considered to be pollutant compounds due to their harmful impacts on aquatic life. However, there have been few rigorous studies of cutting-edge technology used to eradicate XOCs and their presence in bathroom greywater. The present review provides a comprehensive examination of current methodologies used for removing XOCs by photocatalysis of green nanoparticles. It was appeared that zinc oxide nanoparticles (ZnO NPs) have high efficiency (99%) in photocatalysis process. Green synthesis provides proven processes that do not require dangerous chemicals or expensive equipment, making photocatalysis a potential solution for the status quo. XOCs residue was decomposed, and pollutants were eliminated with varied degrees of efficiency using green synthesis ZnO nanoparticles. It is hypothesized that the utilization of photocatalysis can create a greywater treatment system capable of degrading the toxic XOCs in greywater while increasing the pace of production. Hence, this review will be beneficial in improving greywater quality and photocatalysis using green nanoparticles can be an immediate platform in solving the issue regarding the existence of XOCs in greywater in Malaysia. Researchers in the future may benefit from focusing on optimizing photocatalytic degradation using green-synthesis ZnO. It might also help with the creativity and productivity of the next generation of authoritative concerns, notably water conservation.

Synthesis of copper nanoparticles from the aqueous extract of Cynodon dactylon and evaluation of its antimicrobial and photocatalytic properties

The copper nanoparticles (CuNPs) synthesizing potential of Cynodon dactylon aqueous leaf extract and their antibacterial as well as dye degradation potentials were investigated. The synthesized CuNPs was initially characterized by gradual colour change from dark brown to blue in colour and then found absorbance peak at 469 nm. Furthermore, the SEM and DLS analyses showed that biosynthesized CuNPs were spherical in shaped and size ranging from 120 to 129 nm. The FTIR spectrum confirmed the presence of flavonoids, alkaloids, terpenoids, and phenols, which involved in the reduction, capping, and stabilization of CuNPs. This green synthesized CuNPs also demonstrated remarkable antibacterial activity against the bacterial pathogens such as Escherichia coli, Bacillus subtilis and Staphylococcus aureus and Klebsiella pneumoniae. This green synthesized CuNPs exhibited considerable dye degrading potential in the following order as methyl organge > methyl red > Erichrome black T dyes in the presence of sunlight through photocatalytic degradation process. These results conclude that C. dactylon aqueous leaf extract mediated nanoparticles possess remarkable antibacterial and dye degrading potential.

Biogenic Synthesis of Cu-Doped ZnO Photocatalyst for the Removal of Organic Dye

The Cu-doped ZnO photocatalysts were prepared with a green and coprecipitation approach by using water hyacinth (Eichhornia crassipes) aquatic plant extract. In the preparation process, different amount of copper precursors such as 1, 2, 3, 4, and 5% of molar ratio were added to zinc nitrate precursors and abbreviated as Cu-ZnO (1%), Cu-ZnO (2%), Cu-ZnO (3%), Cu-ZnO (4%), and Cu-ZnO (5%), respectively. The characterization of the obtained samples was carried out, and the removal of the methylene blue (MB) dye was examined. Out of all catalysts, Cu-ZnO (3%) had the best photocatalytic performance and 89% of the MB dye was degraded. However, the degradation performances of blank (without catalysts), ZnO, Cu-ZnO (1%), Cu-ZnO (2%), Cu-ZnO (4%), and Cu-ZnO (5%) catalysts were 6, 54, 69, 83, 80, and 73%, respectively. Therefore, the use of water hyacinth plant extract with the optimum amount of Cu added to ZnO during the preparation of the catalyst could have a promising application in the degradation of organic pollutants.

State-of-the-art biosynthesis of tin oxide nanoparticles by chemical precipitation method towards photocatalytic application

Tin oxide (SnO₂) with versatile properties is of substantial standing for practical application, and improved features of the material are demonstrated in the current issue through the integration of nanotechnology with bio-resources leading to what is termed as biosynthesis of SnO₂ nanoparticles (NPs). This review reveals the recent advances in biosynthesis of SnO₂ NPs by chemical precipitation method focused on distinct methodologies, characterization, and reaction mechanism along with a photocatalytic application for dye degradation. According to available literature reviews, numerous bio-based precursors selectively extracted from biological substrates have effectively been applied as capping or reducing agents to achieve the metal oxide NPs. The major precursor obtained from the aqueous extract of root barks of Catunaregam spinosa is found to be 7-hydroxy-6-methoxy-2H-chromen-2-one that has been proposed as a model compound for the reduction of metal ions into nanoparticles due to having highly active functional groups, being abundant in plants (67.475 wt%), easy to extract, and eco benign. In addition, the photocatalytic activity of SnO₂ NPs for the degradation of organic dyes, pharmaceuticals, and agricultural contaminants has been discussed in the context of a promising bio-reduction mechanism of the synthesis. The final properties are supposed to depend exclusively upon a number of factors, e.g., particle size (< 50 nm), bandgap (< 3.6 eV), crystal defects, and catalysts dosage. With this contribution, it has been perceived not only to provide an overview of recent advances in the biosynthesis of SnO₂ NPs but also to indicate the main issues in need aiming to show vision towards innovative outcomes.

Unlocking the potential of biosynthesized zinc oxide nanoparticles for degradation of synthetic organic dyes as wastewater pollutants

The azo dyes released into water from different industries are accumulating in the water bodies and bioaccumulating within living systems thereby affecting environmental health. This is a major concern in developing countries where stringent regulations are not followed for the discharge of industrial waste into water bodies. This has led to the accumulation of various pollutants including dyes. As these developing countries also face acute water shortages and due to the lack of cost-effective systems to remove these pollutants, it is essential to remove these toxic dyes from water bodies, eradicate dyes, or generate fewer toxic derivatives. The photocatalysis mechanism of degradation of azo dyes has gained importance due to its eco-friendly and non-toxic roles in the environment. The zinc nanoparticles act as photocatalysts in combination with plant extracts. Plant-based nanoparticles over the years have shown the potential to degrade dyes efficiently. This is carried out by adjusting the dye and nanoparticle concentrations and combinations of nanoparticles. Our review article considers increasing the efficiency of degradation of dyes using zinc oxide (ZnO) nanoparticles and understanding the photocatalytic mechanisms in the degradation of dyes and the toxic effects of these dyes and nanoparticles in different tropic levels.

Phytofabricated zinc oxide nanoparticles as a nanofungicide for management of Alternaria blight of Brassica

Plant pathogens resistant to the commercially available fungicides and bactericides even at higher concentrations are the biggest challenge for the farmers to control the losses due to plant diseases. The antibacterial and antifungal potential of nanomaterials makes them a suitable candidate for the control of plant diseases. Thus, the present study reports the phytofabricated zinc oxide nanoparticles (ZnO Np's) using aqueous plant leaf extract of Terminalia bellerica (Baheda). Characterization of ZnO nanoparticles was done by ultraviolet-visible (UV-Vis) studies, X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infra-red (FT-IR) analysis, and transmission electron microscopy (TEM). The presence of pure hexagonal wurtzite crystalline structure of ZnO nanoparticles was confirmed by XRD analysis. The TEM images revealed the spherical to hexagonal shaped ZnO nanoparticles with sizes ranging from 20 to 30 nm. The stabilization of synthesized ZnO nanoparticles through the interactions of terpenoids, steroids, phenylpropanoids, flavonoids, phenolic acids, and enzymes present in the leaf extract was suggested by FTIR analysis. The mechanism of the formation of ZnO nanoparticles using Terminalia bellerica (Baheda) (Tb-ZnO Np's) as a bioactive compound is proposed. These phytofabricated ZnO nanoparticles (Tb-ZnO Np's) have shown significant antifungal potential against Alternaria brassicae the causal agent of Alternaria blight disease/leaf spot disease in Brassica species. The microscopic results confirm the changes in mycelium morphology and reduction in the number of spore germination at 0.2 mg/mL concentration Tb-ZnO Np's.

Bioengineered Matricaria recutita Extract-Assisted Palladium Nanoparticles for the Congo Red Dye Degradation and Catalytic Reduction of 4-Nitrophenol to 4-Aminophenol

The green chemistry method is the preferred approach for synthesizing metal and metal oxide nanoparticles because of its low toxicity, environmental friendliness, feasibility, and safety to human health compared with other chemical or physical methods. The present work reports the phytogenic synthesis of palladium nanoparticles (PdNPs) using an aqueous extract of Matricaria recutita (Chamomile). The phytochemical-mediated synthesis of PdNPs is an economical and eco-friendly approach without using toxic elements as reducing and capping or stabilizing agents. The UV-visible spectroscopic characterization was initially used to confirm the preparation of PdNPs using an aqueous extract of M. recutita flowers as a bioreductant for the reduction of Pd2+ to Pd0 without using any extra capping and reducing agents. The appearance of surface plasmon resonance (SPR) peak at 286 nm confirmed the formation of M. recutita extract-based PdNPs. Furthermore, the PdNPs were characterized by TEM, SEM, EDX, XRD, XPS, and FTIR to confirm their proper synthesis. The thermogravimetric analysis (TGA) was implemented to interpret the decomposition pattern and thermal stability of as-synthesized PdNPs. The biosynthesized PdNPs were further applied as a nanocatalyst in degradation of an azo dye Congo red (CR) in the presence of NaBH4. The catalytic reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) was also investigated in the presence of NaBH4. All the catalytic reactions were performed in water, and no significant loss in catalytic activity was observed after recovery and reusability of the biosynthesized PdNPs.

Plant-Mediated Biosynthesis and Photocatalysis Activities of Zinc Oxide Nanoparticles: A Prospect towards Dyes Mineralization

In recent years, nanoparticles synthesis by green synthesis has gained extensive attention as a facile, inexpensive, and environmentally friendly method compared with chemical and physical synthesis methods. This review covered the biosynthesis of zinc oxide nanoparticles (ZnO NPs), including the procedure and mechanism. Factors affecting the formation of ZnO NPs are discussed. The presence of active bioorganic molecules in plant extract played a vital role in the formation of ZnO NPs as a natural green medium in the metallic ion reduction processes. ZnO NPs exhibit attractive photocatalysis properties due to electrochemical stability, high electron mobility, and large surface area. In this review, the procedure and mechanism of the ZnO photocatalysis process are studied. The effects of dyes amount, catalysts, and light on photodegradation efficiency are also considered. This review provides useful information for researchers who are dealing with green synthesis of ZnO NPs. Moreover, it can provide investigators with different perceptions towards the efficiency of biosynthesized ZnO NPs on dyes degradation and its restrictions.

Green-synthesized nanocatalysts and nanomaterials for water treatment: Current challenges and future perspectives

Numerous hazardous environmental pollutants in water bodies, both organic and inorganic, have become a critical global issue. As greener and bio-synthesized versions of nanoparticles exhibit significant promise for wastewater treatment, this review discusses trends and future prospects exploiting the sustainable applications of green-synthesized nanocatalysts and nanomaterials for the removal of contaminants and metal ions from aqueous solutions. Recent trends and challenges about these nanocatalysts and nanomaterials and their potential applications in wastewater treatment and water purification are highlighted including toxicity and biosafety issues. This review delineates the pros and cons and critical issues pertaining to the deployment of these nanomaterials endowed with their superior surface area, mechanical properties, significant chemical reactivity, and cost-effectiveness with low energy consumption, for removal of hazardous materials and contaminants from water; comprehensive coverage of these materials for industrial wastewater remediation, and their recovery is underscored by recent advancements in nanofabrication, encompassing intelligent and smart nanomaterials.

Silver nanoparticles stabilized in polymer hydrogels for catalytic degradation of azo dyes

Fabrication of poly-(N-isopropylmethacrylamide-co-methacrylic acid) [p(NMA)] microgels to be utilized as microreactors to synthesize stable Ag nanoparticles for catalytic reductive degradation of dyes has been addressed in this work. Both p(NMA) microgel and Ag-p(NMA) hybrid microgel systems have been analyzed by Fourier transform infra-red and Dynamic light scattering, Ultraviolet-Visible spectroscopy, X-ray diffraction and Transmission electron microscopy. Catalytic activity of Ag-p(NMA) towards reductive degradation of Congo Red (CR), Methyl Orange (MO) and Alizarin Yellow (AY) was investigated under different operating conditions. Spectrophotometry was employed to check the progress of reaction while the rate constant (k_app) value of degradation reaction was determined under various conditions to optimize reaction parameters for rapid and economical degradation of these dyes. An increase in k_app value was observed by increasing feed content of dye up to a certain value that decreases again by further increment in dye concentration which reflects that catalysis follows Langmuir-Hinshelwood mechanism. A gradual increase in the k_app value was also observed with increasing quantity of hybrid microgel used as a catalyst. By comparing k_app values of degradation of aforementioned dyes, it was found that Ag-p(NMA) hybrid microgel gives better activity for MO dye degradation in comparison to catalytic degradation of CR and AY.

Green synthesis and characterization of copper nanoparticles using Piper retrofractum Vahl extract as bioreductor and capping agent

The copper nanoparticles (CuNPs) have attracted much attention due to their application in diverse fields. The applications of CuNPs depend on their physical and chemical properties. This study presents the first report for the use of medicinal fruit extract of Piper retrofractum Vahl as an eco-friendly reagent in the synthesis of CuNPs using copper sulfate as a starting material. Piper retrofractum Vahl extract was employed as a bioreductor as well as a capping agent in the formation of CuNPs. The reaction process was assisted by sonication and stirring. The influences of extract concentration, pH, temperature, and reaction time on the size of CuNPs were studied in detail. The morphology and structure of synthesized CuNPs were characterized by UV-Vis, FT-IR, SEM-EDS, TEM, and XRD. The UV-Vis measurement showed the surface plasmon resonance (SPR) peak at 234-255 nm, whereas FTIR characteristic peaks of metal-oxygen (Cu-O) were confirmed in the range 550-570 cm-1 and Cu-O-H bonds led to bending absorptions in the region 870-880 cm-1. The synthesized CuNPs possess the spherical shapes and high content of copper (70.3%) as confirmed by SEM-EDS. From the TEM micrograph, it can be seen that the particle size distribution of CuNPs has a high uniformity with a size of 2-10 nm under the optimum condition. The crystalline nature of CuNPs as confirmed by XRD showed the crystallinity phase of 26.4%. The synthesized CuNPs have relatively good stability and could inhibit Escherichia coli and Staphylococcus aureus. The results proved that Piper retrofractum Vahl fruit extract could be applied for a greener synthesis of CuNPs with high uniformity of particle sizes.

The Potential of Pandanus Amaryllifolius Leaves Extract in Fabrication of Dense and Uniform ZnO Microrods

Zinc oxide (ZnO) micro and nanorods were successfully prepared using Pandanus amaryllifolius and hexamethylenetetramine (HMTA) separately as stabilizers using the solution immersion method. Two types of ZnO seed layer were prepared using the same pre-cursor with the different stabilizers. The fabricated ZnO microrods exhibit absorption at ~375 nm as revealed from the UV-Visible absorption spectrum, and this is comparable with ZnO nanorods synthesized using HMTA. X-ray diffraction (XRD) measurement displayed a sharp peak corresponding to the hexagonal wurtzite structure of ZnO microrods. Field emission scanning electron microscopy (FESEM) of ZnO microrods showed average diameter at approximately 500 nm compared to 70 nm of those synthesized from HMTA. A new finding is the ability of Pandanus amaryllifolius as a green stabilizer to grow a dense ZnO microrod structure with high crystallinity. Results reveal that both samples from different stabilizers during the preparation of the ZnO seed layer greatly improved the morphological and structural properties and optical absorption of ZnO. The main outcomes from this study will benefit optoelectronic application, such as in ultraviolet (UV) sensors.

Phyto-Nanocatalysts: Green Synthesis, Characterization, and Applications

Catalysis represents the cornerstone of chemistry, since catalytic processes are ubiquitous in almost all chemical processes developed for obtaining consumer goods. Nanocatalysis represents nowadays an innovative approach to obtain better properties for the catalysts: stable activity, good selectivity, easy to recover, and the possibility to be reused. Over the last few years, for the obtaining of new catalysts, classical methods—based on potential hazardous reagents—have been replaced with new methods emerged by replacing those reagents with plant extracts obtained in different conditions. Due to being diversified in morphology and chemical composition, these materials have different properties and applications, representing a promising area of research. In this context, the present review focuses on the metallic nanocatalysts’ importance, different methods of synthesis with emphasis to the natural compounds used as support, characterization techniques, parameters involved in tailoring the composition, size and shape of nanoparticles and applications in catalysis. This review presents some examples of green nanocatalysts, grouped considering their nature (mono- and bi-metallic nanoparticles, metallic oxides, sulfides, chlorides, and other complex catalysts).

A facile ultrasonic-aided biosynthesis of ZnO nanoparticles using Vaccinium arctostaphylos L. leaf extract and its antidiabetic, antibacterial, and oxidative activity evaluation

The synthesis of nanoparticles often result in the generation of harmful chemical pollutants. As such, many researchers have focused on developing green processes, which include the biosynthesis. In this research, ZnO nanoparticles were prepared using the leaf extract of whortleberry (Vaccinium arctostaphylos L.) via a simple ultrasonic-assisted method. The morphology, crystal size and structure, surface, thermal, and optical properties of the bio-mediated ZnO sample (ZnO_ext) were analyzed and compared with that produced without incorporating the extract (ZnO_chem). The ZnO samples were evaluated for their antidiabetic, antibacterial, as well as their sono- and photo-catalytic performances. Initially, the samples were intraperitoneal injected to alloxan-diabetic rats to examine their treatment efficiency in terms of effects on fasting blood glucose, insulin, cholesterol, high-density lipoprotein, and total triglyceride levels. The ZnO_ext showed significantly higher efficiency for improving the health status of alloxan-diabetic rats in contrast with other tested treatments, vis. ZnO_chem, insulin, and only leaf extract. In addition, both the ZnO samples were assessed against gram-negative and gram-positive bacteria and through sono- and photo-catalytic processes for removing rhodamine B, respectively. The results of this study indicated that not only the ZnO_ext sample was pollution free, it also exhibited higher potentials for treating diabetic rats, bacterial decontamination, and also oxidative removal of organic compounds under the influences of ultrasound and UV irradiations when compared with ZnO_chem sample.

A comprehensive study on antidiabetic and antibacterial activities of ZnO nanoparticles biosynthesized using Silybum marianum L seed extract

Green synthesis of ZnO nanoparticles (NPs) using the plants' extract and their potential application have driven a tremendous interest in recent years. This study reports a green microwave-assisted method for synthesis of ZnO NPs using Silybum marianum L. seed extract. Characteristics of the as-prepared sample was explored in terms of crystalline phase, morphology, composition, surface area, optical, and thermal properties. The particles of the biosynthesized sample (ZnO/extract) had smaller sizes than the chemically produced one (ZnO). The existence of biomolecules from Silybum marianum L seed extract linked to the ZnO/extract sample was approved by various analyses. The ZnO/extract sample was used for treating alloxan-induced diabetic rats and its efficiency was compared with ZnO, extract, and insulin treatments. For this purpose, the levels of blood glucose, insulin, total cholesterol, total triglyceride, and high-density lipoprotein were measured before and after treating with the studied treatment agents and compared with each other. Moreover, the antibacterial activities of both ZnO samples were investigated against E. coli to assess their potential antibacterial application. From the results, ZnO/extract NPs represented an outstanding performance in overcoming the diabetic disorders and good antibacterial activity against the studied bacteria.