Bimetallic nanocomposite (Ag-Au, Ag-Pd, Au-Pd) synthesis using gum kondagogu a natural biopolymer and their catalytic potentials in the degradation of 4-nitrophenol

Microscopic Techniques for Nanomaterials Characterization: A Concise Review

Nanomaterials have been gaining interest due to their remarkable properties at the nanoscale. The surface area of particles becomes high at the nanoscale because of this virtue, they have been used in a bundle of applications like electronics, biomedical, agriculture, wastewater treatment, semiconductor industry, cosmetics, drug delivery, paints, and so forth. The morphology (size and shape) of nanomaterials plays an important role because each application requires the appropriate morphology for better performance. Generally, there are a few microscopic techniques used to characterize nanomaterial morphology, AFM (atomic force microscopy), TEM (transmission electron microscopy), SEM (scanning electron microscopy), and others. In this review, the principles, operations, advantages, and limitations of these microscopic techniques for nanomaterial morphology characterization have been briefly discussed. The existing difficulties and path forward for the development of these techniques have also been highlighted.

Unlocking the potential of plant gums: Bioinformatics-driven insights into green synthesis and applications of metal-based nanoparticles

Plant gums (PGs) are naturally occurring heteropolysaccharides that exude from different plants, typically from their stems, bark, and seeds. They are non-toxic, biodegradable, biocompatible, and cost-effective. PGs are commonly used as emulsifiers, stabilizers, and thickeners in the pharmaceutical, food, and cosmetics industries. Chemically, they are composed of complex sugars, with minor components including proteins, minerals, and flavonoids. Owing to their diverse phytochemical profiles, they have been comprehensively studied over the last couple of decades as reducing, capping, and stabilizing agents for the synthesis of metallic nanoparticles (NPs). Researchers have synthesized various eco-friendly metallic NPs from PGs for potential applications in environmental, industrial, and pharmaceutical domains. This review thoroughly covers the synthesis, characterization techniques, and diverse applications of PG-based metallic NPs. For the first time, using advanced informatics tools like PubChem, ChemSpider, and SwissADME, this study provides novel insights into the molecular interactions and stabilization of PG-based NPs. The review also analyzes the diverse composition of PGs and explores the unique reducing and capping potential of their phytochemicals in the green synthesis of metallic NPs. It also examines the potential drawbacks and proposes possible solutions related to PG-based metallic NP synthesis, along with discussing the future prospects of these nanomaterials.

Bimetallic nanoparticles as pioneering eco-friendly catalysts for remediation of pharmaceuticals and personal care products (PPCPs)

The persistent presence of Pharmaceuticals and Personal Care Products (PPCPs) in aquatic environments poses a significant risk to both human health and ecosystems, with conventional water treatment methods often unable to effectively remove these contaminants. Recent research has identified bimetallic nanoparticles as a promising and eco-friendly solution for PPCP remediation, owing to their enhanced catalytic properties and the synergistic effects between the metals. This review critically examines the synthesis, characterization, and application of bimetallic nanoparticles for the degradation of PPCPs in water. Key synthetic approaches, particularly green synthesis methods, are explored, emphasizing their ability to control nanoparticle morphology, size, and composition. We highlight the novel catalytic mechanisms employed by bimetallic nanoparticles, including electron transfer, surface reactions, and adsorption processes, which contribute to efficient PPCP removal. Furthermore, the influence of critical factors such as nanoparticle size, composition, and surface functionalization on catalytic efficiency is analyzed. Key findings include the superior performance of bimetallic nanoparticles over monometallic counterparts, with specific emphasis on their ability to degrade a wide range of PPCPs under mild conditions. However, challenges such as scalability, stability, and environmental impact remain. This review also provides insights into the future directions for bimetallic nanoparticle development, stressing the importance of interdisciplinary research and collaborative efforts to optimize their design for large-scale, sustainable water treatment applications. Overall, this work offers a comprehensive understanding of how bimetallic nanoparticles can be optimized for sustainable water treatment solutions, highlighting their potential to mitigate the adverse effects of PPCPs on both ecosystems and public health.

Bio-green synthesis of bismuth oxide nanoparticles using almond gum for enhanced photocatalytic degradation of water pollutants and biocompatibility

The discharge of dye-contaminated industrial wastewater is a significant source of water and soil pollution. The eco-friendly synthesis of multifunctional bismuth oxide nanoparticles (BiO-NPs) offers a promising approach for the removal of toxic contaminants. The incorporation of natural polymers in nanoparticle production has gained significant scientific attention due to their environmentally friendly and efficient properties. This study emphasizes the use of almond gum (ALG) as a potent bio-reductant for the green synthesis of BiO-NPs. The synthesized BiO NPs exhibited a surface area of 24.5774 m2/g, demonstrating their potential for enhanced catalytic activity. The photocatalytic activity of the BiO NPs was evaluated by degrading Congo Red and Brilliant Green dyes under visible light irradiation, achieving degradation efficiencies of 90.21 % ± 0.32 and 90.52 % ± 0.29, respectively. Radical trapping experiments confirmed the primary roles of photo-generated electrons and hydroxyl radicals in the degradation process. The reusability analysis demonstrated that the BiO-NPs could be effectively recycled for 4 cycles, maintaining good stability. Degradation intermediates were identified using LCMS. Additionally, the catalytic reduction conversion of 4-nitrophenol to 4-aminophenol using NaBH₄ achieved a degradation efficiency of 92 % ± 0.41 within 32 min. Biocompatibility assessments using NIH/3T3 cell lines indicated that ALG-BiO NPs are safe for environmental applications.

Asymmetric magnetic nanosnowman loaded with AgPd nanocage toward NIR-enhanced catalytic activity

Although bimetallic noble nanostructures often possess high activity in nanocatalysis, their controllable fabrication, tunable catalytic activity, and easy separation remain significant challenges. In this study, an Fe3O4@AgPd/Polydopamine (Fe3O4@AgPd/PDA) nanosnowman loaded with an AgPd nanocage was designed by a one-step template-disposition-redox polymerization method. The AgPd nanocage endowed the product with high catalytic activity for the reduction of organic pollutants (4-NP, MO, MB). Interestingly, under near-infrared (NIR) light, the catalytic kinetics of the Fe3O4@AgPd/PDA nanosnowman on catalytic reduction of organic pollutants increased by 2.6, 1.57, and 5.45 times, respectively. The asymmetric nanostructure facilitated the separation of electron-hole pairs, promoted electron transfer, and accelerated the catalytic activity. Density functional theory (DFT) analysis indicated that the electron transfer between the AgPd alloy and the Fe3O4 nanosphere played a critical role on the high catalytic activity. Moreover, Fe3O4@AgPd/PDA also demonstrated excellent catalytic activity in the Heck carbon-carbon coupling reaction with a >95% conversion rate and >99% selectivity. Owing to the well-encapsulated PDA shell and outstanding magnetic properties, the Fe3O4@AgPd/PDA nanosnowman exhibited good cyclic catalytic activity. With its multi-mode catalysis, NIR-enhanced catalytic activity, and easy separation, the Fe3O4@AgPd/PDA nanosnowman exhibits great application potential in nanocatalysis.

Advances in 4-Nitrophenol Detection and Reduction Methods and Mechanisms: An Updated Review

This review emphasizes the progress in identifying and eliminating para-nitrophenol (4-NP), a toxic organic compound. It covers various strategical methods and materials, including organic and inorganic nanomaterials, for detecting and reducing 4-NP. Detection techniques such as electrochemical methods. Optical fiber-based surface plasmon resonance and photoluminescence, as well as the mechanisms of Förster Resonance Energy Transfer (FRET) and Inner Filter Effect (IFE) in fluorescence detection, are presented. Removal techniques for this contaminant include homogeneous catalysis, electrocatalysis, photocatalysis, and thermocatalysis, and their reaction mechanisms are also discussed. Further, the theoretical perspectives of 4-NP detection and reduction, parameters influencing the activities, and future perspectives are also reviewed in detail.

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.

A review on Ag nanoparticles fabricated in microgels

In recent years, there has been growing interest in the composites of multi-responsive microgels and silver nanoparticles. This innovative hybrid system harnesses the responsive qualities of microgels while capitalizing on the optical and electronic attributes of silver nanoparticles. This combined system demonstrates a rapid response to minor changes in pH, temperature, ionic strength of the medium, and the concentration of specific biological substances. This review article presents an overview of the recent advancements in the synthesis, classification, characterization methods, and properties of microgels loaded with silver nanoparticles. Furthermore, it explores the diverse applications of these responsive microgels containing silver nanoparticles in catalysis, the biomedical field, nanotechnology, and the mitigation of harmful environmental pollutants.

Enhanced photocatalytic degradation of organic pollutants by green-synthesized gold nanoparticles using polysaccharide for environmental remediation

The recent rise in textile dye wastewater discharge into the environment has detrimental effects on living organisms and human health. The present study reports a facile approach to green-synthesized AuNPs employing sesbania gum for catalytic and photocatalytic degradation of organic pollutants. The obtained AuNPs were characterized by various techniques such as UV-vis, FT-IR, SEM, TEM, AFM, zeta potential, LC-MS, and XPS. The XRD patterns revealed a highly crystalline and face-centered cubic structure. XPS and EDX analysis defined the chemical composition and product purity of SBG-AuNPs. Photocatalytic degradation of hazardous dyes congo red and safranin-O using SBG-AuNPs showed a rapid decomposition rate with 94.69 % under visible light irradiation. The effect of pH, dye concentration, and catalyst dose on photodegradation and recyclability was also studied. The kinetic plots were used to calculate the rate constant, showing a pseudo-first-order reaction. Scavenger trap experiments confirmed the role of h+ and superoxide(.O2-) as active species, and LCMS analysis was used to identify the degradation intermediates. The catalytic reduction of SBG-AuNPs was studied for brilliant green (BG) and methylene blue (MB) in the presence of NaBH4, resulting the degradation efficiency of 90.37 % and 84.52 %, respectively. This study presents an innovative approach for designing highly efficient photocatalysts for environmental remediation and wastewater treatment from textile dyes.

Theranostic aspects of palladium-based bimetallic nanoparticles in biomedical field: A state-of-the-art

The exploration of newer antibacterial strategies is driven by antibiotic-resistant microbes that cause serious public health issues. In recent years, nanoscale materials have developed as an alternative method to fight infections. Despite the fact that many nanomaterials have been discovered to be harmful, numerous researchers have shown a keen interest in nanoparticles (NPs) made of noble metals like silver, gold and platinum. To make environmentally safe NPs from plants, green chemistry and nanotechnology have been combined to address the issue of toxicity. The study of bimetallic nanoparticles (BNPs) has increased tremendously in the past 10 years. The production of BNPs mediated by natural extracts is straightforward, low cost and environmentally friendly. Due to their low toxicity, safety and biological stability, noble BNPs with silver, gold, platinum and palladium have the potential to be used in biomedical applications. They have a significant impact on human health and are used in medicine and pharmacy due to their biological characteristics, which include catalytic, antioxidant, antibacterial, antidiabetic, anticancer, hepatoprotective and regenerative activity.

Tuning Pd-to-Ag Ratio to Enhance the Synergistic Activity of Fly Ash-Supported PdxAgy Bimetallic Nanoparticles

Fly ash (FA)-supported bimetallic nanoparticles (PdxAgy/FA) with varying Pd:Ag ratios were prepared by coprecipitation of Pd and Ag involving in situ reduction of Pd(II) and Ag(I) salts in aqueous medium. All the supported nanoparticles were thoroughly characterized with the aid of powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), electron microscopy (field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM)), and elemental analyses, which include inductively coupled plasma-optical emission spectroscopy (ICP-OES) and energy-dispersive X-ray spectroscopy (EDS). A gradual broadening and shifting of PXRD peaks, ascribable to Ag, to higher angles with an increase in the Pd:Ag ratio affirms the alloying of interface between Pd and Ag nanoparticles. The coexistence of Pd and Ag was further confirmed by EDS elemental mapping as well as by the presence of bimetallic lattices on the FA surface, as evident from the high-resolution TEM analysis. The dependency of crystallite size and average size of bimetallic nanoparticles on Ag loading (mol %) was elucidated with the help of a combination of PXRD and TEM studies. Based on XPS analysis, the charge transfer phenomenon between contacting Pd-Ag sites could be evident from the shifting of 3d core electron binding energy for both Pd and Ag compared with monometallic Pd and Ag nanoparticles. Following a pseudo-first-order reaction kinetics, all the nanocatalysts were able to efficiently reduce 4-nitrophenol into 4-aminophenol in aqueous NaBH4. The superior catalytic performance of the bimetallic nanocatalysts (PdxAgy/FA) over their monometallic (Pd100/FA and Ag100/FA) analogues has been demonstrated. Moreover, the tunable synergistic effect of the bimetallic systems has been explored in detail by varying the Pd:Ag mol ratio in a systematic manner which in turn allowed us to achieve an optimum reaction rate (k = 1.050 min-1) for the nitrophenol reduction using a Pd25Ag75/FA system. Most importantly, all the bimetallic nanocatalysts explored here exhibited excellent normalized rate constants (K ≈ 6000-15,000 min-1 mmol-1) compared with other supported bimetallic Pd-Ag nanocatalysts reported in the literature.

Novel, Biosynthesis of Palladium Nanoparticles using Strychnos Potatorum Polysaccharide as a Green sustainable approach; and their effective Catalytic Hydrogenation of 4-Nitrophenol

In the current study, we successfully used strychnos potatorum polysaccharide through autoclaving to synthesize palladium nanoparticles in a green, sustainable process. These polysaccharide act as a stabilizing, capping, and reducing agent. It also used various analytical characterizations, including UV-Visible spectroscopy, FT-IR spectroscopy, X-Ray diffraction (XRD), Scanning electron microscopy (FE-SEM), EDAX, and X-ray photoelectron spectroscopy (XPS), TEM and gel permeation chromatography (GPC) are used to analyze biosynthesized pallidum nanoparticles (PdNPs). The surface plasmon resonance (SPR) band at 276 nm and UV-visible spectroscopy revealed the presence of the generated PdNPs. The XRD data show that PdNPs have crystalline behavior and a pristine face-centered cubic (FCC) structure. The PdNPs were successfully developed by catalytic reduction of 4-nitrophenol (4-NP). The catalytic activity and reusability of the environmentally friendly PdNPs catalyst were demonstrated by achieving a remarkable transformation of 95 % nitrophenol to 4-aminophenol after five cycles. The reaction rate constant (k) for the degradation of 4-nitrophenol (4-NP) using SP-PdNPs as a catalyst is 0.1201 min-1 and R2 0.9867, with a normalized rate constant of (Knor = K/m) of 7.206 s-1 mM-1. These findings provide fundamental knowledge of the catalytic process governing the hydrogenation of p-nitrophenol, which will help designers of effective catalysts. An innovative and affordable technique for creating PdNPs that are environmentally acceptable and can be utilized as effective catalysts in environmental applications is the use of strychnos potatorum gum polysaccharide. The green-synthesized PdNPs can be used for pollutant remediation, including pharmaceutical, domestic, heavy metal, industrial, and pesticide pollutants.

High-performance catalytic reduction of 4-nitrophenol to 4-aminophenol using M-BDC (M = Ag, Co, Cr, Mn, and Zr) metal-organic frameworks

The catalytic activity of pure metal nanoparticles is always limited by aggregation during the reaction. Therefore, promising candidates such as metal-organic frameworks possess benefits due to their 3D porous structures, high stability, and high specific surface area. In this study, effective and reusable catalysts based on M-BDC metal-organic frameworks were synthesized utilizing five different coordinating metal ions (M = Ag, Co, Cr, Mn, and Zr) as metal nodes and 1-4-benzene dicarboxylic acid (BDC) as an organic linker and used in catalytic reduction of 4-Nitrophenol (4-NP) to 4-Aminophenol (4-AP) for the first time. The as-prepared catalysts were characterized using SEM, EDX, XRD, and FTIR techniques. Based on catalytic performance, Co-BDC showed the best catalytic efficiency compared to the other M-BDC MOF catalysts with a conversion yield of about 99.25 in 2 min. All of the catalysts could catalyze the complete reduction of 4-NP to 4-AP at different reaction times (2-10); however, Mn-BDC could not finish the catalytic reduction reaction even after 20 min. The two more efficient catalysts including Co-BDC and Cr-BDC demonstrated high stability and reusability (more than 85% catalytic efficiency) even after 5 cycles.

Green synthesis of biocompatible core-shell (Au-Ag) and hybrid (Au-ZnO and Ag-ZnO) bimetallic nanoparticles and evaluation of their potential antibacterial, antidiabetic, antiglycation and anticancer activities

The fabrication of bimetallic nanoparticles (BNPs) using plant extracts is applauded since it is an environmentally and biologically safe method. In this research, Manilkara zapota leaf extract was utilized to bioreduce metal ions for the production of therapeutically important core-shell Au-Ag and hybrid (Au-ZnO and Ag-ZnO) BNPs. The phytochemical profiling of the leaf extract in terms of total phenolic and flavonoid content is attributed to its high free radical scavenging activity. FTIR data also supported the involvement of these phytochemicals (polyphenols, flavonoids, aromatic compounds and alkynes) in the synthesis of BNPs. Whereas, TEM and XRD showed the formation of small sized (16.57 nm) spherical shaped core-shell Au-Ag BNPs and ZnO nano-needles with spherical AuNPs (48.32 nm) and ZnO nano-rods with spherical AgNP (19.64 nm) hybrid BNPs. The biological activities of BNPs reinforced the fact that they show enhanced therapeutic efficacy as compared to their monometallic components. All BNPs showed comparable antibacterial activities as compared to standard tetracycline discs. While small sized Au-Ag BNPs were most effective in killing human hepato-cellular carcinoma cells (HepG2) in terms of lowest cell viability, highest intracellular ROS/RNS production, loss of mitochondrial membrane potential, induction of caspase-3 gene expression and enhanced caspase-3/7 activity. BNPs also effectively inhibited advanced glycation end products and carbohydrate digesting enzymes which can be used as a nano-medicine for aging and diabetes. The most important finding was the permissible biocompatibility of these BNPs towards brine shrimp larvae and human RBCs, which suggests their environmental and biological safety. This research study gives us insight into the promise of using a green route to synthesize commercially important BNPs with enhanced therapeutic efficacy as compared to conventional treatment options.

Lentinan stabilized bimetallic PdPt3 dendritic nanoparticles with enhanced oxidase-like property for L-cysteine detection

The development of nanozymes with enhanced catalytic activity has been drawing great interest. Lentinan with special structure may be used to prepare bimetallic nanomaterials to enhance their catalytic activity. Herein, lentinan stabilized PdPt₃ dendritic nanoparticles (PdPt₃-LNT NDs) were prepared through reduction of Na₂PdCl₄ and K₂PtCl₄ with a molar ratio of 1:3 using lentinan as a biological template. PdPt₃-LNT NDs had dendritic shape with size of 10.76 ± 1.82 nm. PdPt₃-LNT NDs had the hydrodynamic size about 25.7 nm and the zeta potential between -1.4 mV and - 4.9 mV at different pH. Furthermore, PdPt₃-LNT NDs catalyzed 3,3',5,5'-tetramethylbenzidine (TMB) to produce oxidized TMB, suggesting their oxidase-like property. The catalytic activity of PdPt₃-LNT NDs was the highest when pH was 4 and the temperature was 40 °C. The catalytic mechanism was the generation of ·O₂^- and ¹O₂ from O₂ catalyzed by PdPt₃-LNT NDs. More importantly, L-cysteine detection method was set up based on the oxidase-like property of PdPt₃-LNT NDs. This method had wide linear range for 0-200 μM and low detection limit for 3.099 μM. Taken together, PdPt₃-LNT NDs have good potential applications in bio-related detection in the future.

State of the Art on Green Route Synthesis of Gold/Silver Bimetallic Nanoparticles

Recently, bimetallic nanoparticles (BMNPs) blending the properties of two metals in one nanostructured system have generated enormous interest due to their potential applications in various fields including biosensing, imaging, nanomedicine, and catalysis. BMNPs have been developed later with respect to the monometallic nanoparticles (MNPs) and their physicochemical and biological properties have not yet been comprehensively explored. The manuscript aims at collecting the main design criteria used to synthetize BMNPs focusing on green route synthesis. The influence of experimental parameters such as temperature, time, reagent concentrations, capping agents on the particle growth and colloidal stability are examined. Finally, an overview of their nanotechnological applications and biological profile are presented.