Algal magnetic nickel oxide nanocatalyst in accelerated synthesis of pyridopyrimidine derivatives

Electrochemically Grown Hole-Rich NiO(OH) Thin Films toward Hole-Mediated Very Fast and Selective Enzyme-Free Electrochemical Sensing of Dopamine under Simulated Environment

This work aimed to develop an enzyme-free semiconductor-assisted electrochemical technique for the selective detection of the neurotransmitter dopamine. In this case, electrochemically grown nickel oxyhydroxide [NiO(OH)] thin films were chosen to fabricate the sensing platform, i.e., the electrodes. Chronoamperometry was used to deposit the films on indium tin oxide (ITO) coated glass substrates. The films were thoroughly characterized to establish their structure, composition, phase purity, and electrochemical attributes. Electrochemical sensing characteristics were investigated by means of cyclic and differential pulse voltammetry, steady-state amperometry, and electrochemical impedance spectroscopy. The effects of several interfering agents like glucose, sodium chloride, methanol, hydrogen peroxide, and paracetamol were also studied on the detection attributes of dopamine. Significantly high value of sensitivity (11.87 μA μM-1 cm-2) was obtained for dopamine sensing that was associated with a limit of detection (LoD) of 0.22 μM of dopamine. However, the sensitivity (2.51 μA μM-1 cm-2) and LoD (1.20 μM) obtained for serotonin were inferior compared to those of dopamine. The performance of the electrode toward dopamine sensing was not compromised either in the presence of only serotonin or a series of other electroactive interfering agents, which makes the electrode very much dopamine selective. The dopamine response time was 200 ms, which is notably fast. Extensive studies on the effect of temperature, pH and scan rate on the detection of dopamine by the developed electrode material have also been carried out. The developed electrodes were also found to be notably stable for dopamine detection with a decay of only 6.6% in oxidation peak current density after the 50th cycle. Real-life application of the developed electrode material was checked with urine samples from adult male humans and yielded encouraging results.

Synthesis of Kaolin-Supported Nickel Oxide Composites for the Catalytic Oxidative Degradation of Methylene Blue Dye

Organic dye contamination of water is a contributing factor to environmental pollution and has a negative impact on aquatic ecology. In this study, unsupported NiO and kaolin-supported NiO composites were synthesized by a one-step wet impregnation-precipitation method through the precipitation of nickel hydroxide onto locally accessible, inexpensive, and easily treated kaolin surfaces by using sodium hydroxide as a precipitating agent. The product was calcined at 500 °C and used for the catalytic oxidative degradation of methylene blue (MB) dye in an aqueous solution. The morphology, structure, and interactions of the synthesized materials were explored by SEM, XRD, and FT-IR spectroscopy. The characterization results revealed the fabrication and the growth of NiO on the kaolin surface. To determine the catalytic oxidative degradation performance of the catalyst, many experiments have been performed using the MB dye as a model dye. The catalytic degradation tests confirmed the importance of NiO and the high catalytic activity of the synthesized NiO/kaolin composite toward MB dye degradation. The oxidative degradation results showed that the optimized precursor amount on the kaolin surface could efficiently enhance the removal of MB dye. The kinetic investigation of the catalytic degradation of MB dye fitted the pseudo-first-order kinetic model. High removal efficiency was observed after eight reuse cycles, proving the exceptional stability and reusability of the composite. The catalytic process also proceeded with a low activation energy of 30.5 kJ/mol. In conclusion, the kaolin-supported NiO composite was established to be a favorable catalyst to degrade a model dye (MB) from an aqueous solution in the presence of inexpensive and easily available NaOCl with a catalytic efficiency of the material higher than 99% of the 20.3 mg catalyst within 6 min with an apparent rate constant, kapp, higher than 0.44625 min-1, which is far better than that of the unsupported catalyst with a kapp of 0.0926 min-1 at 10 mg dose in 20 min.

Colorimetric sensor based on biogenic nanomaterials for high sensitive detection of hydrogen peroxide and multi-metals

Hydrogen peroxide (H2O2) and heavy metals, which are among the wastes of the industrial sector, become a threat to living things and the environment above certain concentrations. Therefore, the detection of both H2O2 and heavy metals with simple, low-cost, and fast analytical methods has gained great importance. The use of nanoparticles in colorimetric sensor technology for the detection of these analytes provides great advantages. In recent years, green synthesis of nanomaterials with products that can be considered biowaste is among the popular topics. In this study, silver/silver chloride nanoparticles (Ag@AgCl NPs) were synthesized using the green synthesis method as an eco-friendly and cheap method, the green algae extract was used as a reducing agent. The characterization of Ag@AgCl nanoparticles and green algae extract was carried out with several techniques such as Transmission Electron Microscopy (TEM), UV-Visible spectrometry (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction patterns (XRD) methods were used for characterization. According to TEM analysis, the Ag@AgCl NPs typically spherical in form and range in size from 4 to 10 nm, and UV-vis showed the formation of surface plasmon resonance (SPR) of the Ag@AgCl between 400 and 450 nm. In addition, its activity as a colorimetric sensor for hydrogen peroxide (H2O2) and multi-metal detection was evaluated. Interestingly, Ag/AgCl NPs caused different color formations for 3 metals simultaneously in the sensor study for heavy metal detection, and Fe3+, Cu2+, and Cr6+ ions were detected. The R2 values for H2O2, Fe3+, Cu2+, and Cr6+ were 0.9360, 0.9961, 0.9787, and 0.9625 the limit of detection (LOD) was 43.75, 1.69, 3.18, and 5.05 ppb (ng/mL), respectively. It was determined that Ag@AgCl NPs have the potential to be used as a colorimetric sensor for the detection of H2O2 and heavy metals from wastewater.

Green and sustainable synthesis of nanomaterials: Recent advancements and limitations

Nanomaterials have been widely used in diverse fields of research such as engineering, biomedical science, energy, and environment. At present, chemical and physical methods are the main methods for large-scale synthesis of nanomaterials, but these methods have adverse effects on the environment, and health issues, consume more energy, and are expensive. The green synthesis of nanoparticles is a promising and environmentally friendly approach to producing materials with unique properties. Natural reagents such as herbs, bacteria, fungi, and agricultural waste are used in the green synthesis of nanomaterials instead of hazardous chemicals and reduce the carbon footprint of the synthesis process. Green synthesis of nanomaterials is highly beneficial compared to traditional methods due to its low cost, negligible pollution level, and safety for the environment and human health. Nanoparticles possess enhanced thermal and electrical conductivity, catalytic activity, and biocompatibility, making them highly attractive for a range of applications, including catalysis, energy storage, optics, biological labeling, and cancer therapy. This review article provides a comprehensive overview of recent advancements in the green synthesis routes of different types of nanomaterials, including metal oxide-based, inert metal-based, carbon-based, and composite-based nanoparticles. Moreover, we discuss the various applications of nanoparticles, emphasizing their potential to revolutionize fields such as medicine, electronics energy, and the environment. The factors affecting the green synthesis of nanomaterials, and their limitations are also pointed out to decide the direction of this research field, Overall, this paper highlights the importance of green synthesis in promoting sustainable development in various industries.

Biomedical Applications of Biosynthesized Nickel Oxide Nanoparticles

Nickel oxide nanoparticles have gained tremendous attention recently in a variety of scientific domains thanks to their characteristic chemical, physical, optical, and biological properties. Due to the diversity of applications in various fields, different physicochemical methods have been used to synthesize nickel oxide nanoparticles. However, most conventional methods use hazardous chemicals during synthesis and become liable for potential health risks, while others are expensive and require a lot of energy to synthesize nanoparticles. As a result, the nanoparticles become less biocompatible and biologically inefficient. Biogenic synthesis of nanoparticles is currently proposed as a valuable alternative to the physical and chemical methods, as it is a simple, non-toxic, cheap, green and facile approach. This synthetic method uses biological substrates such as plant extracts, microorganisms, and other biological products to synthesize nickel oxide nanoparticles. The various phytochemicals from plant extracts, enzymes or proteins from microorganisms, and other biological derivatives play as reducing, stabilizing, and capping agents to provide bioactive and biocompatible nickel oxide nanoscale material. This review discusses current findings and trends in the biogenic synthesis of nickel oxide nanoparticles and their biological activities such as antibacterial, antifungal, antileishmanial, and anticancer, with an emphasis on antimicrobial and anticancer activity along with their mechanistic elucidation. Overall, this thorough study provides insight into the possibilities for the future development of green nickel oxide nanoparticles as therapeutic agents for a variety of ailments.

Synthetic strategies of heterocycle-integrated pyridopyrimidine scaffolds supported by nano-catalysts

Nano-catalysts are of special character for the synthesis of organic molecules with high efficiency, and exceptional physicochemical properties. The objective of this study was to present an overview of the literature reports concerning the synthetic strategies supported by nano-catalysts and the biological features of heterocycle-integrated pyridopyrimidine scaffolds. The basic topics include the strategies that were adopted to prepare pyrido[2,3-d]pyrimidines and pyrido[1,2-a]pyrimidines. The synthesis of pyrido[2,3-d]pyrimidines was attained through two-, three-, or four-component reactions. The synthesis of spirocyclic systems, including spiro[indoline-pyridopyrimidine] derivatives and arylation reactions, was investigated. The anticipated mechanisms of the diverse target products, in addition to the preparation of the nanocatalysts, were scrutinized. The privileged antimicrobial characteristics, challenges, literature overview, and future prospectives were consistently investigated.

Ionic Liquid Modified SPION@Chitosan as a Novel and Reusable Superparamagnetic Catalyst for Green One-Pot Synthesis of Pyrido[2,3-d]pyrimidine-dione Derivatives in Water

In this paper, the chitosan-functionalized ionic liquid is modified with superparamagnetic iron oxide nanoparticles to form a novel and reusable catalyst (SPION@CS-IL), which was carried out using an ultrasonic promoted approach. Transmission electron microscopy (TEM), vibrating-sample magnetometer (VSM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and thermogravimetric analysis (TGA) are some of the techniques that are used to fully characterize SPION@CS-IL. The created nanoparticles were discovered to be a reusable heterogeneous superparamagnetic catalyst for the environmentally friendly one-pot synthesis of pyrido[2,3-d]pyrimidine derivatives using a simple three-component reaction approach involving thiobarbituric acid, 4-hydroxy coumarin, and various aromatic aldehydes. The method is studied by performing the reaction under ultrasonic irradiation, while the approach is a “green” method, it uses water as the solvent. The isolated yields of the synthesized products are very advantageous. The catalyst has outstanding reusability and is easily removed from the products via filtration (5 runs). Short reaction times, low catalyst loadings, the nanocatalyst’s capacity to be recycled five times, and the absence of harmful chemical reagents are all significant benefits of this environmentally benign process.

Changes in the content of Puerarin-PLGA nanoparticles in mice under the influence of alcohol and analysis of their antialcoholism

To observe the metabolic changes and antialcoholic effect of Puerarin-PLGA nanoparticles (PUE-NP) in mice. PUE-NP was prepared and characterized by particle size distribution and morphology. The mouse models with acute alcoholism were established to observe their behavioral changes after alcohol poisoning. The expressions of biologically active enzymes such as CRE, BUN, AST, ALT in serum and SOD and TLR4 in liver of mice in each group were detected, and the pathological changes in liver and kidney tissues were observed by HE staining. The PUE-NP metabolism in mice was determined by in vitro release assay and HPLC. PUE-NP nanoparticles had good morphology and structure, and the mouse models with alcohol poisoning were established successfully. Compared with alcohol group, puerarin and PUE-NP increased the disappearance latency time of righting reflex, and the recovery time of righting reflex was significantly shortened. Water maze results showed that Puerarin and PUE-NP had inhibitory effect on impaired memory. HPLC results showed that PUE-NP reached its peak in mice after 1 h, and the content percentage was twice that of puerarin preparation alone, and the distribution time of puerarin concentration in vivo was prolonged, indicating that PLGA nanoparticles had a loading and slow-release effect on puerarin and increased the bioavailability of puerarin in mice. In addition, compared with the alcohol group, Puerarin and PUE-NP improved serum ALT, AST, CRE, and BUN levels in mice, enhanced SOD activity in liver, and inhibited TLR4 expression. The effect was better in the PUE-NP group than in the Puerarin group. PUE-NP delayed the release and metabolism of Puerarin and had better effect in the treatment of the alcoholic liver and kidney injury.

Compressed Hydrogen-Induced Synthesis of Quaternary Trimethyl Chitosan-Silver Nanoparticles with Dual Antibacterial and Antifungal Activities

Quaternary Trimethyl Chitosan (QTMC) and QTMC-Silver Nanoparticles (QTMC-AgNPs) have been synthesized, characterized, and tested as antibacterial agents against Staphylococcus aureus, Escherichia coli, and two plant fungi (Sclerotium rolfsil and Fusarium oxysporum). The as-prepared water-soluble QTMC was in situ reacted with silver nitrate in the presence of clean compressed hydrogen gas (3 bar) as a reducing agent to produce QTMC-AgNPs. UV-vis, ATR-FTIR, HR-TEM/SEM, XPS, DLS, XRD, and TGA/DTG were employed to assess the optical response, morphology/size, surface chemistry, particle size distribution, crystal nature, and thermal stability of the synthesized QTMC-AgNPs, respectively. The as-prepared QTMC-AgNPs were quasi-spherical in shape with an average particle size of 12.5 nm, as determined by ImageJ software utilizing HR-TEM images and further validated by DLS analysis. The development of crystalline nanoparticles was confirmed by the presence of distinct and consistent lattice fringes with an approximate interplanar d-spacing of 2.04 nm in QTMC-AgNPs. The QTMC-AgNPs exhibited significant antibacterial activity with a clear zone of inhibition of 30 mm and 26 mm around the disks against E. coli and S. aureus, respectively. In addition, QTMC-AgNPs showed highly efficient antifungal activity with 100% and 76.67% growth inhibition against two plant pathogens, S. rolfsii and F. oxysporum, respectively, whereas QTMC revealed no impact. Overall, QTMC-AgNPs showed a promising therapeutic potential and,thus, can be considered for drug design rationale.

Green Nanotechnology: Recent Research on Bioresource-Based Nanoparticle Synthesis and Applications

In the last decades, the idea of green nanotechnology has been expanding, and researchers are developing greener and more sustainable techniques for synthesizing nanoparticles (NPs). The major objectives are to fabricate NPs using simple, sustainable, and cost-effective procedures while avoiding the use of hazardous materials that are usually utilized as reducing or capping agents. Many biosources, including plants, bacteria, fungus, yeasts, and algae, have been used to fabricate NPs of various shapes and sizes. The authors of this study emphasized the most current studies for fabricating NPs from biosources and their applications in a wide range of fields. This review addressed studies that cover green techniques for synthesizing nanoparticles of Ag, Au, ZnO, CuO, Co3O4, Fe3O4, TiO2, NiO, Al2O3, Cr2O3, Sm2O3, CeO2, La2O3, and Y2O3. Also, their applications were taken under consideration and discussed.

Green Synthesis of Metal Oxides Semiconductors for Gas Sensing Applications

During recent decades, metal oxide semiconductors (MOS) have sparked more attention in various applications and industries due to their excellent sensing characteristics, thermal stability, abundance, and ease of synthesis. They are reliable and accurate for measuring and monitoring environmentally important toxic gases, such as NO₂, NO, N₂O, H₂S, CO, NH₃, CH₄, SO₂, and CO₂. Compared to other sensing technologies, MOS sensors are lightweight, relatively inexpensive, robust, and have high material sensitivity with fast response times. Green nanotechnology is a developing branch of nanotechnology and aims to decrease the negative effects of the production and application of nanomaterials. For this purpose, organic solvents and chemical reagents are not used to prepare metal nanoparticles. On the contrary, the synthesis of metal or metal oxide nanoparticles is done by microorganisms, either from plant extracts or fungi, yeast, algae, and bacteria. Thus, this review aims at illustrating the possible green synthesis of different metal oxides such as ZnO, TiO₂, CeO₂, SnO₂, In₂O₃, CuO, NiO, WO_3, and Fe₃O₄, as well as metallic nanoparticles doping.

Green synthesis and characterization of copper nanoparticles for investigating their effect on germination and growth of wheat

Today, different types of nanoparticles (NPs) are being synthesized and used for medical and agricultural applications. In this study, copper nanoparticles (CuNPs) were synthesized using the aqueous extract of mint (Mentha longifolia L.). For the characterization of CuNPs, UV-visible spectroscopy, scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectrometry were used. The UV-Visible absorption peak at 558 nm confirmed the formation of CuNPs. The XRD pattern confirmed the phase-centered crystalline nature of CuNPs. FTIR analysis showed the O-H, Cu-H and C-C bonds, indicating the active role of these functional groups as reducing agents of Cu ions to CuNPS. The synthesized NPs were found to have an almost spherical shape with an average size of 23 nm. When applied to wheat, a condition dependent effect of CuNPs was found. Variety 18-Elite Line 1, Elite Line 3, and 18-Elite Line 6 showed maximum germination and growth rate at 50 mg CuNPs/L, while variety 18-Elite Line 5 showed that increase at 25 mg CuNPs/L. Beyond these concentrations, the seed germination and growth of wheat declined. In conclusion, the application of CuNPs showed a beneficial effect in improving the growth of wheat at a certain concentration.

A facile hydrothermal synthesis of high-efficient NiO nanocatalyst for preparation of 3,4-dihydropyrimidin-2(1H)-ones

The present work introduces a one-step and facile hydrothermal procedure as a green process for the first time to synthesize nickel(II) oxide (NiO) nanoparticles. The as-prepared nanomaterials were used as high efficient, low toxic and cost catalyst for the synthesis of some organic compounds. Ni(NO₃)₂ and some natural extract were used as a surfactant for the first time to synthesis NiO nanomaterials. A high synthesis yield (91%) was obtained for S₂. Rietveld analysis affirmed the cubic crystal system of the obtained NiO nanocatalyst. The morphology studies were carried out with the FESEM method and the images revealed a change from non-homogenous to homogenous spherical particles when the Barberryas was used instead of orange blossom surfactant. Besides, the images revealed that the particle size distribution was in the range of 20 to 60 nm. The synthesized catalysts were used for the first time in Biginelli multicomponent reactions (MCRs) for the preparation of 3,4-dihydropyrimidin-2(1H)-ones (DHPMs) under the present facile reaction conditions. High yield (97%) of the final product was achieved at the optimum condensation reaction conditions (Catalyst: 60 mg; temperature: 90 °C and time: 90 min) when ethyl acetoacetate/methyl acetoacetate (1 mmol), benzaldehyde (1 mmol) and urea (1.2 mmol) were used. A kinetic study affirmed pseudo-first-order model for Biginelli reactions followed the pseudo-first-order model.

Copper(II) Schiff-Base Complex Modified UiO-66-NH2(Zr) Metal-Organic Framework Catalysts for Knoevenagel Condensation-Michael Addition-Cyclization Reactions

The synthesis of five- and six-membered oxygen- and nitrogen-containing heterocycles has been regarded as the most fundamental issue in organic chemistry and chemical industry because they are used in producing high-value products. In this study, an efficient, economic, sustainable, and green protocol for multicomponent synthesis has been developed. The one-pot direct Knoevenagel condensation-Michael addition-cyclization sequences for the transformation of aromatic aldehydes, malononitrile, and 4-hydroxycoumarin or phthalhydrazide generate the corresponding dihydropyrano[2,3-c]chromenes and 1H-pyrazolo[1,2-b]phthalazine-5,10-diones over a novel mesoporous metal-organic framework-based supported Cu(II) nanocatalyst [UiO-66@Schiff-Base-Cu(II)] under ambient conditions. Moreover, the [UiO-66@Schiff-Base-Cu(II)] complex efficiently catalyzed the selectively large-scale synthesis of the target molecules with high yield and large turnover numbers. As presented, the catalyst demonstrates excellent reusability and stability and can be recycled up to six runs without noticeable loss of activity. Moreover, ICP-AES analysis showed that no leaching of Cu complex occurred during the recycling process of the heterogeneous [UiO-66@Schiff-Base-Cu(II)] nanocatalyst.

Microwave-Assisted Coprecipitation Synthesis and Local Structural Investigation on NiO, β-Ni(OH)2/Co3O4 Nanosheets, and Co3O4 Nanorods Using X-ray Absorption Spectroscopy at Co-Ni K-edge and Synchrotron X-ray Diffraction

Developing the most straightforward, cheapest, and eco-friendly approaches for synthesizing nanostructures with well-defined morphology having the highest possible surface area to volume ratio is challenging for design and process. In the present work, nanosheets of NiO and β-Ni(OH)₂/Co₃O₄, and nanorods of Co₃O₄ have been synthesized at a large scale via the microwave-assisted chemical coprecipitation method under low temperature and atmospheric pressure. X-ray absorption spectroscopy (XAS) measurements, which comprises both X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) techniques, have been carried out at Co and Ni K-edges to probe the electronic structure of the samples. Also, the local atomic structural, chemical bonding, morphological, and optical properties of the sample were systematically investigated using XAS, synchrotron X-ray diffraction (SXRD), Raman spectroscopy, FTIR, transmission electron microscopy (TEM), and UV-visible spectroscopy. The normalized XANES spectra of the β-Ni(OH)₂/Co₃O₄ nanosheets show the presence of Ni²⁺ and a mixed oxidation state of Co. The disorder factor decreases from β-Ni(OH)₂/Co₃O₄ to Co₃O₄ with increasing Co-O bond length. The SXRD pattern analyzed using Rietveld refinement reveals that NiO has a face-centered cubic phase, Co₃O₄ has the standard spinal structure, and β-Ni(OH)₂/Co₃O₄ has a mixed phase of hexagonal and cubic structures. TEM images revealed the formation of nanosheets for NiO and β-Ni(OH)₂/Co₃O₄ samples and nanorods for Co₃O₄ samples. FTIR and Raman spectra show the formation of β-Ni(OH)₂/Co₃O₄, which reveals the fingerprints of Ni-O and Co-O.

Microporous hierarchically Zn-MOF as an efficient catalyst for the Hantzsch synthesis of polyhydroquinolines

A three-dimensional walnut-like Zn-based MOF microsphere system was designed and synthesized via hydrothermal reaction of zinc salt with 4,6-diamino-2-pyrimidinethiol as a tridentate ligand. Besides, Zn ions were coordinated to the functional groups of the ligand to give a novel Zn-MOF microsphere material. Afterward, the resultant material was thoroughly characterized using various analysis and physico-chemical methods; including, FT-IR, XRD, TGA, EDX, X-ray mapping, SEM, TEM, and BET analysis. The Zn-MOF microspheres were utilized in the Hantzsch reaction for a selective synthesis of asymmetric polyhydroquinolines, using various aromatic aldehydes. Our strategy aims at providing a controlled synthesis of hierarchically nanoporous Zn-MOF microspheres with a well-defined morphology, structure, and excellent catalytic properties. Besides, it would result in having a promising heterogeneous catalyst for a selective synthesis with good yields, short reaction time, a low limit of steric hindrance and electronic effects. Moreover, the heterogeneity of the catalyst is further tested with hot filtration and also the reusability results point.

An environment-friendly methodology for the construction of diversified bicycloacenaphtho[1,2-d]imidazole-8-thione scaffolds using spinel NiFe2O4 nanoparticles as a sustainable catalyst

Herein, we successfully developed an easy access to bicycloacenaphtho[1,2-d]imidazole-8-thione by one-pot three-component MCRs of acenaphthoquinone, aryl or alkyl isothiocyanates and amines using environmentally benevolent and recyclable spinel NiFe₂O₄ nanocatalyst in aqueous ethanol. A broad number of products have been synthesized with both EDGs and EWGs present in the ring which increases the diversity of the protocol. The NiFe₂O₄ nanopowder has been synthesized and thoroughly characterized by powdered XRD, HRTEM, EDX, BET and ICP-AES analysis. The protocol to this bicyclic-heterocycle is noteworthy due to good to excellent yields, practical simplicity and high regioselectivity without any troublesome or hazardous by-products and its easy recovery and reusability of the catalyst. Spinel NiFe₂O₄ NPs-catalysed synthesis of various bicycloacenaphtho[1,2-d]imidazole-8-thione scaffolds under mild and sustainable conditions.

Synthesis and biological activities of alcohol extract of black cumin seeds (Bunium persicum)-based gold nanoparticles and their catalytic applications

Fast, simple, and environmentally friendly gold nanoparticles (Au-NPs) capped and stabilized with black cumin (Bunium persicum) seed alcohol extract are reported. The aqueous gold ions (Au3+) were treated with B. persicum (BP) seed extract, which resulted in a rapid color change to red, indicating the synthesis of Au-NPs. UV-Vis spectroscopy, FTIR, SEM, energy dispersive X-ray (EDX), and X-ray diffraction (XRD) techniques were used to further characterize the Au-NPs. Its stability was assessed against various pH levels and sodium chloride levels (NaCl), different salts of same concentration as well as at a range of temperature (30–100°C). The UV-Vis spectrum in the Au-NPs produced a 540 nm plasmon surface resonance, and a 25–50 nm range of particulates was shown in the SEM analysis. In addition, the FTIR spectra confirmed the inclusion in the capping and decrease of Au-NPs of amines, amide groups, and alcohols. The EDX analysis confirmed the presence of element Au. Furthermore, Au-NPs were tested for enzyme inhibition and antibacterial and antifungal activities and showed remarkable response. These findings have concluded that BP seed extract is an effective bio-reductant of gold nanoparticle synthesis, which can be further applied in different biomedical and pharmaceutical industries.

Enhanced sunlight photocatalytic activity and biosafety of marine-driven synthesized cerium oxide nanoparticles

This contribution presents the biosynthesis, physiochemical properties, toxicity and photocatalytic activity of biogenic CeO₂ NPs using, for the first time, marine oyster extract as an effective and rich source of bioreducing and capping/stabilizing agents in a one-pot recipe. CeO₂ NPs formation was initially confirmed through the color change from light green to pale yellow and subsequently, their corresponding absorption peak was spectroscopically determined at 310 nm with an optical band-gap of 4.67 eV using the DR-UV technique. Further, XRD and Raman analyses indicated that nanoceria possessed face-centered cubic arrangements without any impurities, having an average crystallite size of 10 nm. TEM and SEM results revealed that biogenic CeO₂ NPs was approximately spherical in shape with a median particle size of 15 ± 1 nm. The presence of various bioorganic substances on the surface of nanoparticles was deduced by FTIR and TGA results. It is found that marine-based nanoceria shows no cytotoxic effect on the normal cell, thus indicating their enhanced biocompatibility and biosafety to living organisms. Environmentally, due to energy band gap, visible light-activated CeO₂ nanocatalyst revealed superior photocatalytic performance on degradation of methylene blue pollutant with removal rate of 99%. Owing to the simplicity, cost-effectiveness, and environmentally friendly nature, this novel marine biosynthetic route paves the way for prospective applications of nanoparticles in various areas.

Statistical optimization of experimental parameters for extracellular synthesis of zinc oxide nanoparticles by a novel haloalaliphilic Alkalibacillus sp.W7

Green synthesis of zinc oxide nanoparticles (ZnO NPs) through simple, rapid, eco-friendly and an economical method with a new haloalkaliphilic bacterial strain (Alkalibacillus sp. W7) was investigated. Response surface methodology (RSM) based on Box-Behnken design (BP) was used to optimize the process parameters (ZnSO4.7H2O concentration, temperature, and pH) affecting the size of Alkalibacillus-ZnO NPs (Alk-ZnO NPs). The synthesized nanoparticles were characterized using UV-visible spectrum, X-ray diffraction (XRD), Scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDX), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and Zeta potential. The UV-Vis spectrum of ZnO NPs revealed a characteristic surface plasmon resonance (SPR) peak at 310 nm. XRD pattern confirmed the hexagonal wurtzite structure of highly pure with a crystallite size 19.5 nm. TEM proved the quasi-spherical shape nanoparticles of size ranging from 1 to 30 nm. SEM-EDX showed spherical shaped and displayed a maximum elemental distribution of zinc and oxygen. FTIR provided an evidence that the biofunctional groups of metabolites in Alkalibacillus sp.W7 supernatant acted as viable reducing, capping and stabilizing agents.

Ni–NiO heterojunctions: a versatile nanocatalyst for regioselective halogenation and oxidative esterification of aromatics

Herein, we report a facile method for the synthesis of Ni–NiO heterojunction nanoparticles, which we utilized for the nuclear halogenation reaction of phenol and substituted phenols using N-bromosuccinimide (NBS).