Sustainable synthesis of biogenic ZnO NPs for mitigation of emerging pollutants and pathogens

A facile green synthesis of gold nanoparticles using Canthium parviflorum extract sustainable and energy efficient photocatalytic degradation of organic pollutants for environmental remediation

Organic dye and nitrophenol pollution from textiles and other industries present a substantial risk to people and aquatic life. One of the most essential remediation techniques is photocatalysis, which uses the strength of visible light to decolorize water. The present study reports Canthium Parviflorum (CNP) leaf extract utilization as an effective bio-reductant for green synthesis of Au NPs. A simple, eco-friendly process with low reaction time and temperature was adopted to synthesize CNP extract-mediated Au-NPs (CNP-AuNPs). The prepared AuNPs characterization involving X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron microscopy (XPS) surface area analysis, ultraviolet-visible spectroscopy (UV-Vis). XRD results showed that the cubic-structured AuNPs had a crystallite size of 14.12 nm. Assessment of organic dyes performance in degrading brilliant green (BTG) and amido black 10B (AMB) under visible light irradiation highlights an impressive 83.25% and 86% degradation efficiency within 120 min, accompanied by a kinetic rate constant dyes was found to be 0.0828 min⁻1, BTG, and 0.0123 min⁻1, Furthermore, the reduction of 4-nitrophenol by NaBH4 using CNP-AuNPs as a catalyst demonstrated good catalytic performance and rapid degradation at 89.4%. and rate constant 0.099 min-1 followed pseudo-first-order. The LC-MS analysis identified various intermediates during the degradation of the CR dye. Radical trapping experiments suggest that photogenerated free electrons and hydroxyl radicals are crucial for degrading the amido black 10B dye The AuNPs influenced the significant factors responsible for the photocatalytic activity, such as the increase in range of absorbance, increased e- and h+ pair separation, improvement in the charge transfer process, and active site formation, which significantly enhanced the process of degradation. We found that the CNP-AuNPs could effectively remove dyes and nitrophenol from industrial wastewater.

Advancements in the Synthesis and Functionalization of Zinc Oxide-Based Nanomaterials for Enhanced Oral Cancer Therapy

The fabrication of zinc oxide-based nanomaterials (including natural and synthetic polymers like sulfated polysaccharide, chitosan, and polymethyl methacrylate) has potential to improve oral cancer treatment strategies. This comprehensive review explores the diverse synthesis methods employed to fabricate zinc oxide nanomaterials tailored for oral cancer applications. Several synthesis processes, particularly sol-gel, hydrothermal, and chemical vapor deposition approaches, are thoroughly studied, highlighting their advantages and limitations. The review also examines how synthesis parameters, such as precursor selection, the reaction temperature, and growth conditions, influence both the physicochemical attributes and biological efficacy of the resulting nanomaterials. Furthermore, recent advancements in surface functionalization and modification strategies targeted at improving the targeting specificity and pharmaceutical effectiveness of zinc oxide-based nanomaterials in oral cancer therapy are elucidated. Additionally, the review provides insights into the existing issues and prospective views in the field, emphasizing the need for further research to optimize synthesis methodologies and elucidate the mechanisms underlying the efficacy of zinc oxide-based nanoparticles in oral cancer therapy.

Photo-catalytic dye degradation potentials of Ag-Pd bimetallic nanoparticles synthesized from Vitex negundo

Plant extracts are a great alternative to synthesizing nanoparticles of different metals and metal oxides. This green synthesis method has opened up numerous possibilities in various scientific domains. In present study, Leaf extract from Vitex negundo is a non-deciduous, long-lasting shrub from the Verbenaceae family is used as capping and reducing agents for the synthesis of silver and palladium nanoparticles. The characterization study UV-vis spectrophotometer analysis showed absorbance value around 320 nm which confirming that Ag-Pd nanoparticles have been successfully obtained. Further, SEM is used to investigate the morphology of Ag-Pd NPs, which revealing their spherical and rod-like configuration, aggregation, and the size of the particles are obtained between 50 and 100 nm. The successful synthesis of Ag-Pd NPs was further confirmed by the EDAX chart, which displayed the peak of Ag and Pd at bending energies between 0.5 and 1.5 keV. According to the quantitative study, Ag and Pd ions found about 5.24 and 13.28%, respectively. In addition, surface studies with TEM confirming that synthesized Ag-Pd NPs are predominates with spheres structure morphologies, with sizes averaging 11.20 nm and ranging from 10 to 20 nm. Further, Ag-Pd nanoparticles was applied as potential photocatalyst materials to degrade methylene blue dye and found about 85% of the degradation efficiency within 150 min of the sunlight exposure thus could be used as catalyst to removal of hazardous organic dye molecules.

ZnO-rGO-based electrochemical biosensor for the detection of organophosphorus pesticides

The accurate determination of organophosphorus pesticide residues is of great importance for human disease monitoring and environmental safety. Numerous detection methods exist, among which sensitive monitoring of organophosphorus compounds using electrochemical sensors has gradually become a research hotspot. This paper used acetylcholinesterase (AChE) as an indicator anchored on a zinc oxide-reduced graphene oxide (ZnO-rGO) composite rich in active sites, in which green non-toxic zinc oxide (ZnO) nanomaterials were uniformly distributed on the reduced graphene for rapid detection of organophosphorus. The effects of different ratios of ZnO to reduced graphene on the performance of ZnO-rGO nanocomposites were investigated. The AChE/ZnO-rGO biosensor detects organophosphorus by electrochemical inhibition of acetylcholinesterase in the presence of organophosphorus. The developed electrochemical biosensor has high selectivity and good linearity, and the ZnO-rGO nanocomposite as a matrix for immobilization of acetylcholinesterase and detection of organophosphorus has the potential for highly sensitive pesticide detection.

ZnO nanostructured matrix as nexus catalysts for the removal of emerging pollutants

Water pollution stands as a pressing global environmental concern, elevating the significance of innovative, dependable, and sustainable solutions. This study represents an extensive review of the use of photocatalytic zinc oxide nanoparticles (ZnO NPs) for the removal of emerging pollutants from water and wastewater. The study examines ZnO NPs' different preparation methods, including physical, chemical, and green synthesis, and emphasizes on advantages, disadvantages, preparation factors, and investigation methods for the structural and morphological properties. ZnO NPs demonstrate remarkable properties as photocatalysts; however, their small dimensions pose an issue, leading to potential post-use environmental losses. A strategy to overcome this challenge is scaling up ZnO NP matrices for enhanced stability and efficiency. The paper introduces novel ZnO NP composites, by incorporating supports like carbon and clay that serve as photocatalysts in the removal of emerging pollutants from water and wastewater. In essence, this research underscores the urgency of finding innovative, efficient, and eco-friendly solutions for the removal of emerging pollutants from wastewater and highlights the high removal efficiencies obtained when using ZnO NPs obtained from green synthesis as a photocatalyst. Future research should be developed on the cost-benefit analysis regarding the preparation methods, treatment processes, and value-added product regeneration efficiency.

Light-absorption-driven photocatalysis and antimicrobial potential of PVP-capped zinc oxide nanoparticles

Toxic dyes in water bodies and bacterial pathogens pose serious global challenges to human health and the environment. Zinc oxide nanoparticles (ZnO NPs) demonstrate remarkable photocatalytic and antibacterial potency against reactive dyes and bacterial strains. In this work, PVP-ZnO NPs have been prepared via the co-precipitation method using polyvinylpyrrolidone (PVP) as a surfactant. The NPs' microstructure and morphology were studied using X-ray diffraction (XRD), having a size of 22.13 nm. High-resolution transmission electron microscope (HR-TEM) and field emission scanning electron microscopy (FESEM) analysis showed spherical-shaped PVP-ZnO NPs with sizer ranging from 20 to 30 nm. Fourier Transform Infrared Spectroscopy (FT-IR) confirmed the hybrid nature of the NPs, and UV-Vis spectroscopy showed an absorption peak at 367 nm. The PVP-ZnO NPs exhibited high photocatalytic activity, achieving 88% and nearly 95% degradation of reactive red-141 azo dye with 10 mg and 20 mg catalyst dosages, respectively. The antibacterial properties of the NPs were demonstrated against Escherichia coli and Bacillus subtilis, with inhibition zones of 24 mm and 20 mm, respectively. These findings suggest that PVP-ZnO NPs can be effectively used for water treatment, targeting both dye and pathogenic contaminants.

Sargassum natans I Algae: An Alternative for a Greener Approach for the Synthesis of ZnO Nanostructures with Biological and Environmental Applications

In this work, the influence of the Sargassum natans I alga extract on the morphological characteristics of synthesized ZnO nanostructures, with potential biological and environmental applications, was evaluated. For this purpose, different ZnO geometries were synthesized by the co-precipitation method, using Sargassum natans I alga extract as stabilizing agent. Four extract volumes (5, 10, 20, and 50 mL) were evaluated to obtain the different nanostructures. Moreover, a sample by chemical synthesis, without the addition of extract, was prepared. The characterization of the ZnO samples was carried out by UV-Vis spectroscopy, FT-IR spectroscopy, X-ray diffraction, and scanning electron microscopy. The results showed that the Sargassum alga extract has a fundamental role in the stabilization process of the ZnO nanoparticles. In addition, it was shown that the increase in the Sargassum alga extract leads to preferential growth and arrangement, obtaining well-defined shaped particles. ZnO nanostructures demonstrated significant anti-inflammatory response by the in vitro egg albumin protein denaturation for biological purposes. Additionally, quantitative antibacterial analysis (AA) showed that the ZnO nanostructures synthesized with 10 and 20 mL of extract demonstrated high AA against Gram (+) S. aureus and moderate AA behavior against Gram (-) P. aeruginosa, depending on the ZnO arrangement induced by the Sargassum natans I alga extract and the nanoparticles' concentration (ca. 3200 µg/mL). Additionally, ZnO samples were evaluated as photocatalytic materials through the degradation of organic dyes. Complete degradation of both methyl violet and malachite green were achieved using the ZnO sample synthesized with 50 mL of extract. In all cases, the well-defined morphology of ZnO induced by the Sargassum natans I alga extract played a key role in the combined biological/environmental performance.

Magnetically recoverable sol-gel auto-combustion developed Ni1-xCuxDyyFe2-yO4 magnetic nanoparticles for photocatalytic, electrocatalytic, and antibacterial applications

Copper and dysprosium doped NiFe₂O₄ magnetic nanomaterials, Ni_1-xCu_xDy_yFe_2-yO₄ (x = y = 0.00, 0.01, 0.02, 0.03), was prepared by utilizing sol-gel auto-combustion approach to inspect the photodegradation of methylene blue (MB) pollutant and also, to perform the electrocatalytic water splitting and antibacterial studies. The XRD analysis reveal the growth of a single-phase spinel cubic structure for produced nanomaterials. The magnetic traits show an increasing trend in saturation magnetization (M_s) from 40.71 to 47.90 emu/g along with a decreasing behaviour of coercivity from 158.09 to 142.31 Oe at lower and higher Cu and Dy doping content (x = 0.0-0.01). The study of optical band gap values of copper and dysprosium-doped nickel nanomaterials decreased from 1.71 to 1.52 eV. This will increase the photocatalytic degradation of methylene blue pollutant from 88.57% to 93.67% under natural sunlight, respectively. These findings clearly show that under natural sunlight irradiation for 60 min, the produced N4 photocatalyst displays the greatest photocatalytic activity with a maximum removal percentage of 93.67%. The electrocatalytic characteristics of produced magnetic nanomaterials for both HER and OER were examined with a Calomel electrode taking as a reference in a 0.5 N H₂SO₄ and 0.1 N KOH electrolyte. The N4 electrode demonstrated considerable 10 and 0.024 mA/cm² of current density, with onset potentials of 0.99 and 1.5 V for HER and OER and also, have tafel slopes of 58.04 and 295 mV/dec, respectively. The antibacterial activity for produced magnetic nanomaterials was examined against various bacteria (Bacillus subtilis, Staphylococcus aureus, S. typhi, and P. aeruginosa) in which N3 sample produced significant inhibition zone against gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) but no zone of inhibition against gram-negative bacteria (S. typhi and P. aeruginosa). With all these superior traits, the produced magnetic nanomaterials are highly valuable for the wastewater remediation, hydrogen evolution, and biological applications.

Facile preparation of porphyrin@g-C3N4/Ag nanocomposite for improved photocatalytic degradation of organic dyes in aqueous solution

In the quest of improving the photocatalytic efficiency of photocatalysts, the combination of two and more semiconductors recently has garnered significant attention among scientists in the field. The doping of conductive metals is also an effective pathway to improve photocatalytic performance by avoiding electron/hole pair recombination and enhancing photon energy absorption. This work presented a design and fabrication of porphyrin@g-C₃N₄/Ag nanocomposite using acid-base neutralization-induced self-assembly approach from monomeric porphyrin and g-C₃N₄/Ag material. g-C₃N₄/Ag material was synthesized by a green reductant of Cleistocalyx operculatus leaf extract. Electron scanning microscopy (SEM), X-ray diffraction (XRD), FT-IR spectroscopy, and UV-vis spectrometer were utilized to analyse the properties of the prepared materials. The prepared porphyrin@g-C₃N₄/Ag nanocomposite showed well integration of porphyrin nanostructures on the g-C₃N₄/Ag's surface, in which porphyrin nanofiber was of the diameter in nanoscales and the length of several micrometers, and Ag NPs had an average particle size of less than 20 nm. The photocatalytic behavior of the resultant nanocomposite was tested for the degradation of Rhodamine B dye, which exhibited a remarkable RhB photodegrading percentage. The possible mechanism for photocatalysis of the porphyrin@g-C₃N₄/Ag nanocomposite toward Rhodamine B dye was also proposed and discussed.

Catalytic and antimicrobial potential of green synthesized Au and Au@Ag core-shell nanoparticles

It has been a never-ending quest to design a safe, cost-effective, and environmentally acceptable technology for eliminating contaminants from water and countering antibiotic resistance. Herein, a waste leaf extract from the abundant and renewable plant, Brassica oleracea var. gongylodes, is introduced as a cost-effective and sustainable means to generate gold (Au) and Au@Ag core-shell nanoparticles (NPs). In comparison to the bare Au NPs, bimetallic NPs demonstrated improved catalytic and antibacterial capabilities. The reduction process conforms to the pseudo-first-order kinetic, and apparent rate constant (k_app) was calculated to be 0.46 min^-1, according to the kinetic analysis. With both microbial pathogens, E. coli (Gram-negative) and B. subtilis (Gram-positive), an increment of Au and Au@Ag NPs lead to a considerable improvement in the zone of clearance. The present outcome is a step forward in the establishment of a viable and cost-effective catalytic and antibacterial platform based on bimetallic NPs that could be generated in an inexpensive and eco-friendly manner.