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Green synthesis of metal nanoparticles using plants
Abstract
In recent years, the development of efficient green chemistry methods for synthesis of metal nanoparticles has become a major focus of researchers. They have investigated in order to find an eco-friendly technique for production of well-characterized nanoparticles. One of the most considered methods is production of metal nanoparticles using organisms. Among these organisms plants seem to be the best candidates and they are suitable for large-scale biosynthesis of nanoparticles. Nanoparticles produced by plants are more stable and the rate of synthesis is faster than in the case of microorganisms. Moreover, the nanoparticles are more various in shape and size in comparison with those produced by other organisms. The advantages of using plant and plant-derived materials for biosynthesis of metal nanoparticles have interested researchers to investigate mechanisms of metal ions uptake and bioreduction by plants, and to understand the
possible mechanism of metal nanoparticle formation in plants. In this review, most of the plants used in metal nanoparticle synthesis are shown.
... A key aspect of nanoparticle-based plant disease management is the green synthesis of nanoparticles using plant extracts, microbes, and other biological agents. This eco-friendly approach avoids the use of harmful chemicals and improves the biocompatibility of the resulting nanoparticles (Iravani, 2011;Laishram et al., 2024). Green-synthesized nanoparticles have demonstrated significant potential in controlling plant pathogens and are increasingly being explored as sustainable alternatives to conventional agrochemicals. ...
... Nanoparticles: Green synthesis of nanoparticles using plant extracts, bacteria, fungi, and algae provides an ecofriendly and cost-effective alternative to chemical synthesis. These biogenic nanoparticles often exhibit enhanced stability and reduced toxicity due to surface functionalization with biomolecules from the biological source (Iravani, 2011). For example, silver and copper nanoparticles synthesized using neem (Azadirachta indica) or tulsi (Ocimum sanctum) extracts have shown strong antimicrobial effects against plant pathogens (Singh et al., 2015). ...
Plant diseases remain one of the most critical constraints in global agriculture, leading to substantial crop losses and threatening food security. Conventional disease management strategies are increasingly limited by environmental concerns, the emergence of resistant pathogen strains, and inefficiencies in delivery and targeting. In this context, nanotechnology presents a promising platform for sustainable and effective plant disease management. Nanoparticles (NPs), due to their unique physicochemical properties, have demonstrated potent antimicrobial activity against a wide range of pathogens, including fungi, bacteria, viruses, and nematodes. Metal-based NPs such as silver (AgNPs), copper (CuNPs), and zinc oxide (ZnO NPs); carbon-based nanomaterials like carbon nanotubes (CNTs) and graphene oxide (GO); and biodegradable polymer-based NPs such as chitosan play crucial roles in pathogen inhibition. Their mechanisms of action include physical disruption of pathogen structures, generation of reactive oxygen species (ROS), interference with DNA and enzymatic activity, modulation of plant immune responses, and targeted delivery of agrochemicals. Moreover, green synthesis methods enhance their biocompatibility and environmental safety. Despite their potential, the widespread adoption of NPs in agriculture is hindered by concerns over phytotoxicity, environmental persistence, and the absence of comprehensive regulatory frameworks. This review critically explores the types, mechanisms, and pathogen-specific applications of nanoparticles in agriculture, while addressing existing challenges and outlining future directions for integrating nanotechnology into sustainable crop protection strategies.
... Another central mechanism is the induction of cell cycle arrest. Curcumin modulates the expression of cyclins and cyclindependent kinases (CDKs), particularly reducing cyclin D1 and CDK4/6 levels, which halts progression through the G1/S checkpoint [10]. Additionally, it upregulates the tumor suppressor protein p21^WAF1/CIP1^, further enforcing cell cycle inhibition and curtailing uncontrolled division of TNBC cells. ...
... A fundamental aspect of green synthesis is the avoidance of toxic reducing and capping agents. Instead, biological entities such as plant phytochemicals, microbial enzymes, and polysaccharides serve dual roles in nanoparticle formation-acting both as reducing agents to convert metal ions into nanoparticles and as stabilizers to prevent aggregation [10]. These biologically derived components eliminate the need for synthetic additives, making the nanoparticles safer for biomedical applications, especially in drug delivery and cancer therapy. ...
... Nanoparticles can be synthesized through the Topdown method that comprises breaking larger solid particles into smaller ones (Iravani, 2011)and the Bottom-up method that collects and assembles gas or liquid molecules into defined structures (Makarov et al., 2014). The top-down approach is not reliable, as perfect surface nanoparticles cannot be obtained due to roughness. ...
... While in the bottom-up approach, seamless nanoparticles are obtained. Another advantage of this approach is that no waste materials are formed during this process, as small-sized nanoparticles are obtained (Iravani, 2011;Makarov et al., 2014). Nanoparticles are made from different techniques, e.g., physical and chemical methods. ...
Parasitic infections continue to pose a significant global health burden, particularly in tropical and subtropical regions. Traditional antiparasitic drugs often suffer from issues such as poor bioavailability, drug resistance, and non-specific toxicity. Nanotechnology has emerged as a promising approach for enhancing drug delivery by improving drug stability, targeting infected tissues, and reducing side effects. To treat protozoan and helminthic illnesses, this study examines recent developments in drug delivery systems based on nanotechnology, including nanoparticles, liposomes, dendrimers, and polymeric carriers. Additionally, we discuss the challenges, safety concerns, and prospects of nanomedicine in the field of parasitology.
... For the synthesis of NPs, a variety of techniques can be used, although these techniques can be broadly categorized into two kinds i.e. (1) Top-down approach and (2) Bottomup approach (Wang and Xia, 2004;Iravani, 2011). These methods further subdivide into several groups according on the protocols that have been established, the operation, and the reaction condition. ...
... Initially, a bigger molecule broke down into smaller units, and these units were subsequently transformed into acceptable nanoparticles. Physical vapor deposition (PVD), CVD, grinding/milling, and other breakdown processes are examples of this approach (Iravani, 2011). Coconut shell (CS) nanoparticles are manufactured using this method. ...
Nanoparticles (NPs) are tiny materials ranging in size from 1 to 100 nm that
can be categorized into several classes based on their properties, forms, or sizes.
Fullerenes, metal NPs, ceramic NPs, and polymeric NPs are among the various
categories. NPs have distinct physical and chemical properties due to their large
surface area and nanoscale size. Their optical properties are said to be size-dependent, resulting in varied colors due to absorption in the visible area. Several procedures for creating nanoparticles have been developed that are safe for the environment. Plant pests and diseases are critical yield-limiting factors that considerably affect crop productivity globally, causing serious difficulties for food security and still the world’s major agricultural concern. Crop protection will be successful if various nanotechnology tools are employed in the field, as they have the ability to improve the sensitivity, accuracy, and speed of plant disease detection and control, as well as facilitate high-throughput analysis. This developing technology has the potential to be a game changer in global sustainable agriculture. This chapter comprehensively discusses different strategies for nanomaterial production, numerous characterization methodologies, nanoparticle features, and sector-specific applications of nanotechnology for crop protection.
... Overlapping of nanoparticles or forming nanoclusters could also contribute to this discrepancy. Thus, the large crystallite size likely reflects aggregated nanoparticle clusters rather than discrete individual particles [42][43][44] . Zeta potential analysis was performed to evaluate the surface charge and dispersity of the nanoparticles. ...
... As per DLS, the storage of the sample before analysis or the phytoconstituents from C. rotundus acting as natural capping agents may have an impact on agglomeration in solution, which is most likely the cause of the DLS data indicating a greater size (633 nm). The hydrodynamic radius may be increased by these surface-bound biomolecules, which could cause DLS measurements to overestimate the true size of the nanoparticle 42,45 . However, as per the results of Zeta potential, it confirmed that the Ag-NPs exhibited a surface potential of − 13.98 mV with a polydispersity index of 0.483, indicating good dispersion of the particles. ...
Wound healing is a complex biological process that can be hindered by persistent infections and inflammation, especially in the presence of multidrug-resistant (MDR) bacteria. Silver nanoparticles (AgNPs) have demonstrated significant antimicrobial efficacy; however, concerns regarding their toxicity have limited their therapeutic application. Methods: In this study, we developed a biocompatible Ag-NPs-based hydrogel using Cyperus rotundus extract via a green synthesis approach for prospective wound healing applications. The synthesized AgNPs were characterized for their physicochemical properties, confirming their stability and antibacterial potency against E. coli and S. epidermidis. The Ag-NPs-loaded hydrogel was formulated using Carbopol 974P and evaluated for its physicochemical properties, antibacterial activity, anti-inflammatory potential, and cytotoxicity. Results: Characterization studies confirmed the successful synthesis of AgNPs, exhibiting potent antibacterial, antioxidant, and anti-inflammatory properties. The Ag-NPs-loaded hydrogel demonstrated significant wound contraction in an excision wound model, comparable to standard treatment. Additionally, in vitro safety evaluations confirmed excellent biocompatibility, minimizing toxicity concerns associated with conventional silver formulations. Conclusions: These findings suggest that the developed Ag-NPs-based hydrogel is an effective, natural, and safer alternative for advanced wound care, warranting further clinical validation.
... Recent empirical investigations have revealed that the attributes and potential applications of nanoparticles are contingent upon their phases, dimensions, and morphological characteristics. A burgeoning trend in the synthesis of nanoparticles is the adoption of green technologies, which seek to mitigate ecological ramifications and enhance sustainability Balasooriya et al., 2017;Iravani, 2011). ...
... The unique chemical and physical features of inorganic nano-sized particles, whether simple or complex, make them an increasingly significant component in the invention of novel nanodevices with a large range of biological, physical, pharmacological, and biomedical approaches (Loureiro et al., 2016;Khan et al., 2019). For the assembly of NPs, a variety of techniques can be used, two classes are broadly categorized into two classes: (i) top-down approaches and (ii) bottom-up approaches (Wang and Xia, 2004;Iravani, 2011;Bayda et al., 2019) (Fig. 1). Three layers make up NPs (i) a superficial layer that could be functionalized with a range of polymers, tiny molecules, metals, and surfactants; (ii) an outer shell layer; and (iii) a core moiety that is the exact term for the NPs. ...
... Furthermore, the smaller size and higher surface-to-volume ratio of AgNPs are additional factors that contribute to their antioxidant effect. This can be explained by the fact that catechins provide a more effective coating and stabilization while reducing silver ions [65,66]. In conclusion, in our study, AgNPs exhibited higher antioxidant activity than AuNPs due to their high surface reactivity, more effective catechin coating, and the easier interaction of surface functional groups with radicals such as DPPH. ...
In this study, gold (Au) and silver (Ag) nanoparticles were synthesized from an aqueous solution of catechin extract obtained by sequential microwave extraction (MAE) and supercritical fluid extraction (SFE) for the first time at different temperatures (25, 35, 45 °C) in accordance with the characteristics of green chemistry. For the synthesis of Ag and Au nanoparticles at three different temperatures, 100 mL of an aqueous 1 mM AgNO3 solution was added to different volumes (0.5–4 mL) of catechin extract solutions. In the biosynthesis of Ag and Au nanoparticles, 1 mM AgNO3 solution and 0.5 mM HAuCl4.3H2O at 25 °C and 0.5 mL extract volume were determined as the best parameters. The crystalline structures of AgNP and AuNP nanoparticles synthesized using catechin extract in accordance with green chemistry principles were confirmed by X-ray diffraction (XRD) analysis. The average crystallite sizes were determined to be 18.82 nm for AgNPs and 14.31 nm for AuNPs. Transmission electron microscopy (TEM) revealed size distributions of 19.50 ± 5.52 nm for AgNPs and 20.06 ± 5.38 nm for AuNPs. Dynamic light scattering (DLS) analysis showed that the hydrodynamic diameters were 37.61 ± 1.25 nm for AgNPs and 37.9 ± 0.26 nm for AuNPs. The zeta potential values were measured as –20.4 mV for AgNPs and –22.6 mV for AuNPs. The PDI (polydispersity index) values were found to be 0.271 ± 0.006 for AgNPs and 0.295 ± 0.004 for AuNPs. The effects of various concentrations of AgNPs and AuNPs on DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity were determined. At a concentration of 0.91 mg/mL, AgNPs exhibited a high antioxidant activity of 89.24%, while AuNPs showed 70.46% activity at 2.677 mg/mL. In comparison, the standard antioxidant Trolox demonstrated 91.19% inhibition at a concentration of 0.012 mg/mL. The IC₅₀ values of green-synthesized AgNPs, AuNPs, and standard Trolox were calculated as 1.151, 1.485, and 0.006 mg/mL, respectively. The results obtained from this study indicate that biologically synthesized AgNPs and AuNPs can be effectively used as potent antioxidants.
... The development of standardised regulatory norms is necessary for the widespread adoption of DES in food, pharmaceutical, and environmental applications [258][259][260][261][262][263][264][265][266][267][268][269][270][271][272][273][274][275]. Future studies ought to look into: University, Part -B, 38(1), (2025) ...
Deep eutectic solvents (DESs) as green solvents and sustainable solvents used as replacements for traditional organic solvents and highly applicable for various purposes due to their good chemical properties, such as depression freezing point, low volatility, being biofriendly in nature, less toxicity, environmental friendliness, non-toxic nature, ability to be recycled, reusability, biodegradability, nontoxicity, low vapour pressure, low flammability, etc. These unique physicochemical properties make them perfect for applications in extraction, catalysts, electrochemistry, biotransformation, extracting bioactive compounds, as a green solvent, for nanomaterial synthesis, for metal extraction, for drug delivery, for gas capture, for therapeutic applications, etc. In this paper review, study their method of preparation, types of DESs and its significance in various fields, along with their salient physicochemical properties. DESs can be synthesised by the mixing of hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) chemical molecules with the proper ratio and heating them. Synthesised DESs It's characterised by spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR) techniques, etc. Future research directions are also covered, along with some issues. This analysis offers insights into DES's function in promoting sustainable chemical processes by critically assessing its potential in green chemistry.
... Compared to other biological systems, using plants offers a number of advantages, as the research study shows. Compared to alternative techniques, the plants provide more stable nanoparticles and are safe to handle (6). ...
The green manufacturing of nanoparticles utilising biological systems, particularly plant extracts, is a new field in nanotechnology. Zinc oxide nanoparticles were created in this work using an aqueous extract of Pterocarpus Santalinus leaves and zinc salt (zinc nitrate) as precursors. The green synthesised zinc oxide nanoparticles were assessed using a UV-visible spectrophotometer. Utilising SEM with EDAX, the shape of the zinc oxide nanoparticles was described. Research employing X-ray diffraction (XRD) equipment revealed that zinc oxide nanoparticles are crystalline and pure. Utilising FTIR spectroscopy, the specific functional groups in charge of the reduction, stabilisation, and capping agents seen in the nanoparticles were identified. Using the disc diffusion technique, the antibacterial activity of synthesised ZnO nanoparticles against a multihost bacterium (Pseudomonas cichorii) was evaluated. ZnO nanoparticles had superior antibacterial action. The findings of the antioxidant testing were positive. This work demonstrates that zinc oxide nanoparticles made through green synthesis have inherent anti-microbial and antioxidant qualities that might be used to make agricultural insecticides.
... Compared to other biological systems, using plants offers a number of advantages, as the research study shows. Compared to alternative techniques, the plants provide more stable nanoparticles and are safe to handle (6). ...
The green manufacturing of nanoparticles utilising biological systems, particularly plant extracts, is a new field in nanotechnology. Zinc oxide nanoparticles were created in this work using an aqueous extract of Pterocarpus Santalinus leaves and zinc salt (zinc nitrate) as precursors. The green synthesised zinc oxide nanoparticles were assessed using a UV-visible spectrophotometer. Utilising SEM with EDAX, the shape of the zinc oxide nanoparticles was described. Research employing X-ray diffraction (XRD) equipment revealed that zinc oxide nanoparticles are crystalline and pure. Utilising FTIR spectroscopy, the specific functional groups in charge of the reduction, stabilisation, and capping agents seen in the nanoparticles were identified. Using the disc diffusion technique, the antibacterial activity of synthesised ZnO nanoparticles against a multihost bacterium (Pseudomonas cichorii) was evaluated. ZnO nanoparticles had superior antibacterial action. The findings of the antioxidant testing were positive. This work demonstrates that zinc oxide nanoparticles made through green synthesis have inherent anti-microbial and antioxidant qualities that might be used to make agricultural insecticides.
... Top-down synthesisIn top-down synthesis, a larger bulk material is broken down into smaller molecular units, which subsequently convert into nanoparticles. Techniques such as grinding, milling, and physical vapour deposition are commonly used in this approach, as they involve the disintegration of larger structures into nanoscale particles(Iravani, 2011) A. Mechanical milling Among the diverse top-down techniques, mechanical milling stands out as the most widely utilised method for producing a range of nanoparticles. This process involves the milling and subsequent annealing of nanoparticles, where various elements are ground together under an inert atmosphere to prevent unwanted reactions during synthesis(Yadav et al.,2012) ...
This review explores the multidisciplinary realm of nanotechnology, highlighting its principles, historical evolution, and wide-ranging applications. Beginning with an overview of nanoscience and its foundational concepts, the paper delves into nanomaterials' classification and synthesis methods, including both top-down and bottom-up approaches. A comparative insight into green synthesis and conventional chemical synthesis of nanoparticles is also discussed, where green synthesis is emphasized as an eco-friendly, sustainable, and less toxic alternative, in contrast to chemical synthesis, which often involves hazardous reagents and generates harmful by-products. The paper further emphasizes the unique properties of nanomaterials that differ significantly from their bulk counterparts, making them suitable for diverse applications. Key areas of focus include the role of nanotechnology in electronics, medicine, environmental protection, and agriculture. Additionally, the paper addresses potential risks, toxicity concerns, and the prospects of nanotechnology, stressing the importance of responsible development and application. This comprehensive review aims to provide a foundational understanding of nanotechnology and its transformative potential across various sectors.
... Nanoparticles (NPs) are ultrafine particles in the size typically between 1 and 100 nanometres (nm) in at least one dimension (Donough et al., 2024). Owing to their small size, NPs possess unique physical, chemical, and biological characteristics that differ notably from those of bulk materials (Hazrat Ali et al., 2023;Iravani, 2011;Sagar et al., 2023). These properties make NPs valuable across disciplines, including medicine, electronics and environmental science (Abdelghany et al., 2017;Patil et al., 2022). ...
... All of the reasons for more environmentally friendly and economical synthesis are met by plantmediated techniques. The plant-based synthesis approach is cost-effective for the large-scale production of highly stable nanomaterials [11]. The main merits of plant-mediated methods are as follows [12][13][14]: Fast and simple process for industrial scale production at economical pressure and temperature, utilizing aqueous solvents and non-toxically and safe for medicinal customs and cost-effective due to the availability of plant. ...
... Also, MNPs can absorb certain noxious chemicals on their surface; and lead to negative efficacy on health and medical applications. Therefore, there is a necessity for the development of safe, non-toxic, and inexpensive reagents and environmentally and trustworthy technique, without the employment of high energy, temperature, and pressure which actuate scientists towards bio-based greener processes [10][11][12]. Recently, greener synthesis of MNPs such as Au [13], Ag [14], TiO 2 [15], Cu 2 O [16], ZnO [17] and MgO [18] is attracting attention. ...
... A review of relevant the literature indicates that plant-based systems offer significant advantages over other biological methods for nanoparticle synthesis. Plant materials are readily available, pose minimal safety hazards, and facilitate the production of more stable nanoparticles [21]. Plants containing phytochemicals and biomolecules, including polyphenols, alkaloids, flavonoids, amides, saponins, glycosides, terpenes, and tannins, are crucial for the green synthesis of ZnO NPs because these compounds act as capping and reducing agents [22,23]. ...
In recent years, environmentally friendly methods for synthesizing nanoparticles have gained significant attention. This study aimed to develop a green, cost-effective, and facile method for synthesizing ZnO NPs using black chokeberry fruit (Aronia melanocarpa L.) extract and to evaluate their antibacterial, antidiabetic, and photocatalytic activities. Characterization of the phyto-mediated synthesized ZnO NPs was carried out using UV-Visible spectroscopy, Fourier Transform Infrared (FT-IR) spectroscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) and X-ray diffraction (XRD) analysis. The antioxidant activity of the ZnO NPs was assessed using the 2,2-diphenyl-1-picrylhydrazyl hydrate (DPPH) radical scavenging assay, yielding a calculated IC50 value of 154.2 µg/mL. The ZnO NPs exhibited effective antibacterial activity against Staphylococcus aureus, Listeria monocytogenes, Salmonella enteritidis, and Escherichia coli with minimum inhibitory concentrations (MIC) of 137.5 µg/mL, 135.4 µg/mL, 137.7 µg/mL, and 185.2 µg/mL, respectively. Additionally, the ZnO NPs demonstrated antidiabetic activity by effectively inhibiting α-amylase, an enzyme involved in carbohydrate digestion, with an IC50 value of 2.355 mg/mL. Moreover, the ZnO NPs exhibited significant degradation of methylene blue (MB) dye, achieving a 95.5% degradation efficiency within 120 min under UV irradiation. These results suggest that phytogenically synthesized ZnO NPs using black chokeberry fruit extract have great promise for degrading environmental pollutants and may be valuable in various biomedical applications, including antioxidant, antibacterial, and antidiabetic therapies.
... Green nanoparticle synthesis, particularly using plant extracts, is gaining momentum as an emerging trend in green chemistry. This method not only reduces the need for hazardous reagents but also utilizes naturally derived biomolecules as reducing and stabilizing agents [6][7][8]. ...
... Green synthesis of CuNPs has gained momentum due to its eco-friendly and cost-effective nature, avoiding toxic chemicals and harsh reaction conditions. Plant extracts, bacteria, fungi, and algal biomolecules serve as reducing and capping agents, offering natural steric stabilization (Iravani, 2011). For instance, Azadirachta indica (neem) and Camellia sinensis (green tea) extracts have been used successfully to synthesize CuNPs with high anticancer potential (Mittal et al., 2014). ...
... Plants, in particular, have emerged as the most promising candidates for large-scale biosynthesis of NPs. Notably, NPs derived from plants exhibit enhanced stability and a faster synthesis rate compared with those produced by microorganisms [11]. Green synthesis methods utilize environmentally friendly chemicals to produce NPs and utilize gentle solvents like water, natural extracts. ...
The current investigation determines the fabrication and characterization of magnesium hydroxide nanoparticles (Mg(OH) 2 NPs) with the help of C. gigantea latex via biological method. The size, shape, morphology, functional groups and stability of biogenic Mg(OH) 2 NPs were analysed by microscopic and spectroscopical analyses. Mg–O vibration, C–O stretch, O–H and C–H bend were detected by FTIR analysis. Crystalline nature of biogenic Mg(OH) 2 NPs was confirmed by X‐ray diffraction (XRD). FESEM with EDX analysis revealed the morphology and elemental composition of biogenic Mg(OH) 2 NPs and proved that formation of nano petal‐shaped Mg(OH) 2 NPs. Moreover, the synthesized biogenic Mg(OH) 2 NPs were studied for antioxidant and antibacterial activities against wound‐causing bacteria by standard methods. As‐synthesized Mg(OH) 2 NPs showed significant antioxidant activity as compared with ascorbic acid and it had potential antibacterial activity. The study concluded that Mg(OH) 2 NPs with antioxidant and antibacterial properties can be synthesized using C. gigantea latex by green chemistry approach and may be used for formulation of new drugs and gel for wound healing and any other medical application.
... The green synthesis of nanoparticles using plant extracts has emerged as a sustainable alternative to conventional chemical and physical methods. Early studies by Iravani et al. (2011) demonstrated that plant phytochemicals, such as flavonoids, phenolic acids, and alkaloids, act as natural reducing and capping agents during nanoparticle synthesis, eliminating the need for toxic chemicals. For example, silver nanoparticles synthesized using Azadirachta indica leaf extract showed significant antibacterial properties (Sharma et al., 2012). ...
... Utilizing natural extracts can lead to less precise control over the growth of AuNPs, resulting in a heterogeneous distribution of sizes and shapes. This variability can affect the surface plasmon effect in an unpredictable manner, which may be beneficial for applications such as sensors for biomarkers or in photothermal therapies (Elia et al., 2014;Iravani et al., 2011). Additionally, the use of biological products that contain complex molecules often requires multiple reduction 18(35), e69858, July-December 2025 | https: //doi.org/10.22201/ceiich.24485691e.2025.35.69858 Williams de Jesús Jiménez-Martínez, Juan Carlos Vázquez-Lira processes, making their characterization crucial for process optimization (Albrecht et al., 2006). ...
Green chemistry, based on the principles of Paul Anastas and John Warner, promotes the sustainable synthesis of gold nanoparticles (AuNPs) by reducing the use of toxic substances and minimizing hazardous waste. Traditional methods, which employ reducing agents such as sodium borohydride (NaBH4), generate harmful by-products, while green approaches use natural agents such as plant extracts and microorganisms that act as reductants and stabilizers, without generating toxic waste. These methods are not only safer, but also improve the biocompatibility of AuNPs, making them much more suitable for biomedical applications, notably drug delivery, targeted therapies and molecular diagnostics. The use of natural sources and biocatalysts, such as enzymes or microorganisms, facilitates synthesis under mild conditions, allowing greater control over the shape and size of AuNPs. These nanoparticles can be designed to specifically target cells, improving the efficacy of cancer treatments and reducing adverse effects. In this article we present the main features and advantages of green synthesis of AuNPs for a promising alternative with significant applications in nanomedicine and other technological areas.
... Green-synthesized silver nanoparticles exhibit signi cant antimicrobial activity and hold promise for future biomedical applications. Further studies are needed to evaluate cytotoxicity and in vivo e cacy [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. ...
This study investigates the antimicrobial properties of silver nanoparticles (AgNPs) synthesized using green tea extract against common pathogenic bacteria. The biosynthesized nanoparticles were characterized using UV–Vis spectroscopy and scanning electron microscopy (SEM). Their efficacy was tested against Escherichia coli , Staphylococcus aureus , and Pseudomonas aeruginosa . The green-synthesized AgNPs demonstrated significant antimicrobial activity, with maximum inhibition observed against S. aureus . These findings suggest the potential of plant-mediated nanoparticles as alternative antimicrobial agents.
... Among the various methods of nanoparticle synthesis, plant-mediated or "green synthesis" approaches are particularly appealing because of their cost-effectiveness, biocompatibility, and environmental sustainability. This method utilizes natural plant compounds to synthesize nanoparticles that exhibit superior stability and reduced toxicity compared to those produced via traditional physical and chemical techniques [12,13]. ...
The increasing impacts of climate change, global warming, and water scarcity are intensifying drought risk and compromising global food security. To mitigate these challenges, green-synthesized nanoparticles (NPs) derived from plant extracts have recently emerged as an innovative tool for enhancing crop resilience to abiotic stresses such as drought. Moringa enables eco-friendly nanoparticle production with diverse uses. Although Moringa enhances plant traits and its NPs have antimicrobial properties, limited research exists on their ability to improve plant tolerance to abiotic stress. Here, we investigated the potential of copper oxide (CuO) nanoparticles synthesized from Moringa plant extracts to alleviate drought stress in tomato plants (Solanum lycopersicum). The Moringa-based CuO NPs were characterized via UV‒Vis spectrophotometry, Zeta potential, FTIR, SEM, and TEM. Foliar applications of the NPs at various concentrations (3, 6, and 9 mg/L) were tested on tomato seedlings under normal and drought-induced conditions (10% PEG), alongside two controls: non-stressed control (water treatment) and drought stress control (PEG treatment). Physiological assessments showed that 6 mg/L Moringa-based CuO NPs were most effective under drought stress, significantly reducing leaf yellowing and increasing shoot length by 11%, root length by 21%, total dry biomass by 34% increase, and total chlorophyll content by 32% increase at (p < 0.05) compared to the drought stress control. Furthermore, at the molecular level, gene expression analysis revealed the upregulation of PAL, CHS, and HQT, which are genes critical to the stress response and secondary metabolism in tomato plants. Notably, the combination of CuO NPs with PEG amplified gene expression, indicating a synergistic effect on improving drought tolerance. These findings highlight the potential of the use of Moringa-synthesized CuO nanoparticles as a sustainable, eco-friendly strategy to mitigate drought stress in economic crops such as tomatoes. This new green approach offers a promising solution for bolstering food security in the face of climate change and water scarcity challenges.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12870-025-06708-2.
... In various studies the presence of silver nanoparticles has been confirmed by the appearance of a visible surface plasmon resonance (SPR) peak covering the wavelength range of 410 to 450 nm during the production of AgNPs as reported by [7,11,46]. The existence of colloidal particles facilitated the prolonged stability to AgNPs [26,66]. The synthesis of silver nanoparticles is subjected to the effects of diverse physicochemical parameters like pH, temperature, precursor concentration, and reaction time. ...
Nanotechnology gained much attention of scientists due to their distinctive physicochemical characteristics. The purpose of this study is to examine the biogenic production of silver nanoparticles (AgNPs) using the biological extract of Syzygium cumini a well-known medicinal plant that cure various ailments and investigate its therapeutic potential. Confirmation of silver NPs was done by examining the absorption spectra of silver nanoparticles, significant peak was observed at a wavelength of 450nm. Scanning electron microscope results revealed spherical shaped AgNPs in cluster form with slight agglomeration. The FTIR revels various functional groups that present in plant extract and X-ray diffraction analysis showed crystalline size of ~ 47nm. The AgNPs demonstrated antiproliferative activities against HepG2, Huh-7 (human liver), A-549 (human lung) and MCF-7 (human breast) cancer cell line with 84.3, 56.1, 47.4 and 61.5% inhibition respectively at an optimum concentration of 50 µg/mL. The antidiabetic assay revealed 54.6% inhibition of α-glucosidase enzyme at an optimum concentration of 50 µg/mL. The study also revealed that super optimal concentration might have adverse effect in inhibiting cancer cell proliferation and α-glucosidase enzyme. This study paves the way for Syzygium cumini mediated AgNPs to be useful therapeutic agents in the field of health care and medicine to cure various diseases.
... In bioremediation, genetically modified organisms (GMOs) have great benefits since they give an environmentally sustainable substitute with fewer health risks than conventional physicochemical techniques, which can be less friendly and maybe dangerous (Iravani 2011). Using the pCLG2 (M5) and pGPMT (M4) plasmids, the genetically edited E. coli strain JM109 is a prominent example. ...
Rapid elevation of global population along with increased urbanization and industrialization afflict the water resources leading to the blooming of wastewater. Two or more aromatic rings fused with organic compound Polycyclic Aromatic Hydrocarbons (PAHs) emerged worldwide through anthropogenic processes, mainly due to the incomplete combustion of organic fuels. In accordance with the United States Environmental Protection Agency (USEPA), there are 16 PAHs that are deemed as primary pollutants. These are toxic to the living organisms due to their pervasive existence, rebelliousness, potential for bioaccumulation and carcinogenic venture. Several methods including fixation, incineration and oxidation are put forward to remove PAHs. Occasionally some fictional toxic products are produced by the incomplete removal of PAHs. Bioremediation is one of the ecological techniques to remove the PAHs. Microbial biodegradation is considered as an effective and inexpensive technique to remove PAHs along with other hydrocarbons and xenobiotic compounds and are accomplished by few PAHs degrading bacteria including Haemophilus spp., Mycobacterium spp., Paenibacillus spp., Pseudomonas aeruginosa, P. fluorescens, Rhodococcus spp. along with few biosurfactant-producing microbes. The novel biochemical events involved in hydrocarbon catabolism are microbial physical adaptation, their acquisition and uptake. The bioremediation efficacy can be further ameliorated through genetic modification of the microbes. This chapter will focus on the eco-friendly treatment for the PAHs remediation in in situ and ex situ. This chapter will explore the remediation of the PAH by-products through the multi-process conjunctional treatment processes under the green therapy.
... The development of standardised regulatory norms is necessary for the widespread adoption of DES in food, pharmaceutical, and environmental applications [258][259][260][261][262][263][264][265][266][267][268][269][270][271][272][273][274][275]. Future studies ought to look into: University, Part -B, 38(1), (2025) ...
Deep eutectic solvents (DESs) as green solvents and sustainable solvents used as replacements for traditional organic solvents and highly applicable for various purposes due to their good chemical properties, such as depression freezing point, low volatility, being biofriendly in nature, less toxicity, environmental friendliness, non-toxic nature, ability to be recycled, reusability, biodegradability, nontoxicity, low vapour pressure, low flammability, etc. These unique physicochemical properties make them perfect for applications in extraction, catalysts, electrochemistry, biotransformation, extracting bioactive compounds, as a green solvent, for nanomaterial synthesis, for metal extraction, for drug delivery, for gas capture, for therapeutic applications, etc. In this paper review, study their method of preparation, types of DESs and its significance in various fields, along with their salient physicochemical properties. DESs can be synthesised by the mixing of hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) chemical molecules with the proper ratio and heating them. Synthesised DESs It's characterised by spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR) techniques, etc. Future research directions are also covered, along with some issues. This analysis offers insights into DES's function in promoting sustainable chemical processes by critically assessing its potential in green chemistry.
This research explores the eco-friendly synthesis of iron oxide nanoparticles using Beauveria bassiana fungus in a biological way, and proposes a sustainable method for environmental remediation and resource recovery. This method is eco-friendly and clean. The synthesized nanoparticles are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and atomic energy microscopy (AFM) with the aim of studying the structural and optical properties. The synthesised iron nanoparticles in an average grain size of ~ 31 nm. The topography and features show somewhat a regular surface. The optical properties of iron oxide are studied using UV/Vis spectroscopy, and the energy gap is found to be (4.8 eV), The absorption peaks at the wavelength (264 nm) within the ultraviolet range, Therefore, another absorption peak is obtained at the wavelength (970 nm). the condition for optical absorption to occur is fulfilled. The FTIR spectrum show functional groups which have been recorded in a range between (400 – 3900) cm ⁻¹ . The most important of these regions is the first region which is located between (700 – 1000) cm ⁻¹ . This goes back to the effective bond (Metal - Oxide), and there is a peak at (1665 cm ⁻¹ ), which is goes back to the carbonyl group, C=O. Also, there is a peak, indicating broad expansion, which is located at (3485 cm ⁻¹ ). Specifically, this peak assures the presence of hydrogen-bonded groups and also represents the (O-H) vibrations of the alcohol or phenolic. We conclude that the biosynthesis method using Beauveria bassiana is a clean, non-toxic and environmentally acceptable method for the production of iron oxide nanoparticles.
Nanotechnology is an emerging field in science that exhibits significant promise in the synthesis of nanomaterials for diverse applications. Traditionally, these nanomaterials were manufactured using hazardous and labor-intensive physical and chemical processes. Nevertheless, in recent years, researchers have developed safer, more scalable, and environmentally friendly methods for green synthesis. The problem addressed in this study is the need for an environmentally friendly and efficient synthesis process for titanium dioxide nanoparticles (TiO2 NPs) with enhanced properties. The aim of this work is to describe the synthesis of TiO2 NPs with various plant extracts using a green approach and to evaluate the physicochemical characteristics and potential applications of the resulting nanoparticles. This study focuses on understanding how the integration of plant extracts influences the properties of TiO2 NPs, particularly in terms of their structural, optical, and functional characteristics. The novelty lies in the use of plant extracts as bio-reductants and capping agents, which not only provides a safer and more sustainable synthesis method but also enhances the functional properties of TiO2 NPs. This green synthesis approach reduces the use of harmful chemicals, making the process more environmentally friendly and economically viable, with potential applications in photocatalysis, antibacterial, and antioxidant activities. The TiO2 NPs possess diverse functionalities, including photocatalysis, antibacterial properties, and antioxidant properties. The initial precursor, such as a metal salt, undergoes transformation into the desired nanoparticles through the actions of plants exactly. Bio-reduction and capping processes are carried out by secondary metabolites found in bacteria and plants. The results demonstrated that the plant extract-mediated TiO2 NPs exhibited enhanced photocatalytic activity, superior antibacterial effects, and higher antioxidant potential compared to chemically synthesized TiO2 NPs. This highlights the potential of green synthesis methods in producing nanomaterials with improved functional properties for a wide range of applications.
Global agriculture faces unprecedented challenges due to the increasing frequency of climate change, which is leading to continuously declining crop yields. Simultaneously, the growing world population is impacting food demand. Crop growth and yield are negatively affected by rising biotic stress in agriculture. Biotic stress stems from various organisms, including bacteria, fungi, viruses, insects, nematodes, and mites, that exploit the biological systems of host plants. A cost-effective, non-toxic, and eco-friendly means of obtaining nanoparticles (NPs) is through biological acquisition techniques. This paper not only offers a thorough explanation of biological agents such as plants, algae, bacteria, fungi, actinomycetes, and yeast, but also presents recent data on several strategies for obtaining nanoparticles. Compared to physical, chemical, and biological methods of producing nanoparticles, the biological approach provides significant advantages, such as non-toxicity and environmental friendliness, which support its extensive use in agricultural applications. The active nanomaterials used in crop protection include metallic nanoparticles like gold, silver oxide, zinc oxide, copper oxide, and titanium oxide. The unique properties of nanomaterials—like their high specific surface area, uniform particle size, and excellent biocompatibility—enhance the effectiveness and stability of agricultural chemicals, provide effective and selective methods for crop protection, and offer potential for further improvements. This review highlights the transformative potential of NPs in plant health and crop disease management.
Silver nanoparticles (AgNPs) have emerged as promising agents in cancer diagnostics and/or therapy, demonstrating a lot of possible pharmacological actions. However, understanding the pharmacokinetics and safety profiles of nanoparticles, which is crucial for their clinical application, still raises many questions. Studies indicate that AgNPs can accumulate in tumour tissues, improving drug delivery and specificity. However, their interaction with biological systems necessitates thorough safety evaluations. Classical methods for assessing AgNPs’ safety include cytotoxicity assays, genotoxicity tests, and histopathological examinations. However, novel techniques are emerging, such as advanced imaging and biomarker analysis, offering more precise toxicity assessments. Prediction models, including computational simulations and in silico analyses, are being developed to forecast AgNPs’ toxicity profiles. These models aim to reduce reliance on animal testing and expedite the evaluation process. To mitigate potential risks associated with nanoparticle-based therapies, strategies such as surface modification, controlled release systems, and targeted delivery are being explored. These methods aim to enhance therapeutic efficacy while minimizing adverse effects. The main aim of this review article is to describe AgNPs from the point of view of their pharmacokinetic/toxicokinetic profile in the light of modern knowledge. Special attention will be given to novel methods for assessing the safety and toxicity profiles of AgNPs, providing insights into their interactions with cancer therapies and their potential clinical applications.
Environmental pollution has become a major issue since chemical species from different sources (e.g., textile industries, paper industries, dye industries, etc.) have been introduced into our living environment. If these chemical species are not properly treated, they will be highly toxic and hazardous to living organisms. Thus, it is important to remove the chemical species before discharge into the environment. Varieties of techniques, such as degradation, adsorption, photocatalysis, etc., have been employed to remove the chemical species. In recent years, metal and metal oxide nanoparticles, which exhibit high degradation and adsorption performance, have been widely used in environmental treatment. Here we provide a detailed overview of the environmental applications of metal and metal oxide nanoparticles, particularly in water treatment. The metal and metal oxide nanoparticles possess immense potential in environmental applications, however, challenges such as agglomeration, toxicity concerns, and cost-effectiveness are acknowledged. Through a comprehensive analysis of existing literature, this review systematically integrates critical research data. And it presents relevant research findings, aiming to explore environmentally sustainable nanomaterials with superior contaminant removal efficiency and broad applicability.
Nanotechnology is widely recognised as one of the most important advances in science from the last decades. Its numerous applications and rapidly expanding demand have led the way for innovative approaches to the synthesis of nanomaterials of higher quality. Green synthesis of silver nanoparticles (AgNPs) using the Dimor-phocalyx glabellus (Sny. Tritaxis glabella Thwaites R.Y.Yu & Welzen var. glabella) which has many medicinal properties including treatment of psoriasis and it also has anti-diabetic, anti-diuretic and anti-rheumatic property. The present study assessed with methanolic extract leaves of D. glabellus and its characterization through GCÀMS analysis to identify the phyto-constituents. Moreover, AgNPs were synthesized using the leaf extract of D. glabellus and subsequently characterized using UVÀVis Spectrophotometer, Scanning Electron Microscope (SEM), and Fourier Transform Infrared Spectroscopy (FTIR) techniques to verify the formation of AgNPs within the plant extract. The analysis of FTIR spectra revealed the presence of various functional groups such as carboxyl, amine, and phenolic compounds which play a vital role in the reduction of silver ions in the leaf extract of D. glabellus. Furthermore, the phyto-constituents compounds in the plant extract were studied in-silico for possible interaction with TNF-alpha, vital for rheumatoid arthritis and other diseases. This suggests the potential use of these phyto-constituents of D. glabellus as a natural remedy for the treatment of Rheumatoid Arthritis, offering a promising alternative to traditional medications.
Green synthesis of Ag nanoparticles from vegetable extracts is a promising option for using natural biomolecules in the synthesis of metallic nanoparticles, being significant for the development of functional materials as an alternative to traditional
routes. This study focuses on synthesis, characterization, and evaluation of silver nanoparticles derived from the aqueous extract of pineapple peel in antibacterial assay. The well-formation nanoparticles were demonstrated by a band in 460 nm. The material synthesized by water bath and ultrasound showed Z-average values ranging from 117.0 to 153.2 nm and 127.0 to 142.3 nm, respectively, at concentrations of 1, 3, and 5 mmol L−1. The different conditions of the zeta potential ranged from −21.4 to −10.1 mV and polydispersity index from 0.167 to 0.322. The TEM images of material obtained by water bath and ultrasound methods showed spherical particles with smooth and irregular edges. High concentrations of total phenolic compounds in nanomaterial (159.92–326.9 mg equiv. GA·100 g−1) were found relative to the aqueous extract of pineapple peel (132.0 mg equiv. GA·100 g−1). The tested silver nanoparticles exhibited ABTS radical inhibition ranging from 19.11 to 77.90% and were effective against Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa and against Gram-positive bacteria Staphylococcus aureus. The minimum inhibitory concentration (MIC) of nanoparticles was found to be higher for Gram-positive bacteria (21.25–42.25 mg mL−1) compared to Gram-negative bacteria (2.6–21.25 mg mL−1), indicating that Gram-negative bacteria are more susceptible to the inhibitory activity. The synthesis method by water bath and ultrasound showed significant cytotoxic activity when tested in human breast cancer MCF-7 and murine melanoma B16F10 cell lines. The IC 50 values showed to be similar for those obtained by water bath or ultrasound, using the same AgNO3 concentration for both methods.
Osteosarcoma (OS), chondrosarcoma (CHS), and Ewing sarcoma (EWS) are the main types of bone cancer (BC). OS is the most common BC in this group. It is most common in children and older people, especially in their long bones. Treatments for bone sarcomas and tumors have slowly improved, so researchers began looking into additional and alternative approaches to standard therapies. Therefore, the ability to precisely manipulate metallic nanoparticles (MNPs)' form, size, charge, and surface modification makes them very useful in treating bone cancer. However, due to the biocompatibility and possible toxicity of MNPs, MNP has limits for clinical use in treating BC. Therefore, the green synthesis of MNPs is achieved by bio-reducing metallic ions, which results in the creation of NPs, using living entities or their extracts. Green MNPs derived from natural sources provide a secure and environmentally responsible solution. Benefits of green MNPs include tailored medicine delivery and biocompatibility. Green MNPs reduce damage to healthy cells while improving the targeting of bone cancer cells. In this study, we reviewed how different MNPs synthesized using green methods can help treat various types of BC. This work reviewed the usual way of making MNPs for treating BC, the problems with this standard way of making MNPs, and the benefits and possible future uses of green synthetic MNPs for treating BC.
Graphical Abstract
The synthesis of nanoparticles (NPs) has gained prominence due to their distinct properties and wide-ranging applications. Among various methods, green synthesis stands out for its environmentally friendly approach. This study investigates the green synthesis of silver nanoparticles (AgNPs) using the aqueous extract of Umbrella plant flowers ( Schefflera actinophylla ). Phytochemical analysis of the extract identified the presence of alkaloids, terpenoids, saponins, resins, carbohydrates, and phenols. Silver nanoparticles were synthesized using a 0.1 M AgNO 3 solution and monitored through UV-visible spectroscopy, which revealed an absorption peak at 370 nm. Characterization through infrared (FTIR) spectroscopy, Field Emission Scanning Electron Microscopy (FE-SEM), Dynamic Light Scattering (DLS), and Zeta potential measurements indicated an average particle size of 8.9 nm and a zeta potential of −8.8 mV. FE-SEM images showed nanoparticles in various shapes. The AgNPs exhibited significant antimicrobial activity against common bacteria such as Staphylococcus aureus , Bacillus subtilis , Pseudomonas aeruginosa , and Escherichia coli , as well as fungi including Aspergillus niger and Candida albicans . Furthermore, the nanoparticles displayed notable antioxidant activity with an IC 50 value of 37.025 μg/ml. This study highlights the benefits of using plant-based methods for nanoparticle synthesis, offering an eco-friendly alternative to conventional chemical processes, thus reducing pollution and mitigating antibiotic resistance in microbes.
This study presents the green synthesis of cerium oxide nanoparticles (CeO₂ NPs) using Albizia julibrissin flower extract, offering an eco‐friendly and cost‐effective approach to nanoparticle fabrication. The synthesized CeO₂ NPs were characterized using UV–vis spectroscopy, which revealed a characteristic absorption peak at 310 nm, XRD confirming a cubic fluorite structure with an average crystallite size of 30 nm, and SEM/TEM showing a spherical morphology with particle sizes ranging from 10–25 nm. The nanoparticles exhibited potent antibacterial activity, with inhibition zones of 17.6 ± 0.8 mm against Escherichia coli and 15.2 ± 0.6 mm against Staphylococcus aureus, demonstrating their broad‐spectrum antimicrobial efficacy. The antioxidant potential, evaluated via DPPH assay, showed a radical scavenging activity of 78.4% at 100 µg/mL, comparable to standard antioxidants. The cytotoxicity study on MCF‐7 breast cancer cells revealed an IC₅₀ value of 48.6 µg/mL, indicating significant anticancer activity. Furthermore, the photocatalytic degradation of methylene blue dye under visible light illumination achieved a 92.3% degradation efficiency within 120 min, highlighting the environmental remediation potential of CeO₂ NPs. These findings establish plant‐mediated CeO₂ NPs as promising candidates for biomedical and environmental applications.
Nanomaterials (NMs) have gained tremendous attention in various applications in the modern era. The most significant challenge associated with NMs is their strong propensity to aggregate. The chemical surface modification of NMs has garnered notable attention in managing NM dispersion and aggregation. Among the modification approaches, the silane modification of NMs has generated great interest among researchers as a versatile approach to tailoring the surface characteristics of NMs. This review comprehensively examined the recent advancements in silane modification techniques with a focus on triboelectric nanogenerator (TENG) applications. It provides an overview of silane chemistry and its interaction with diverse NMs, elucidating the underlying mechanisms governing the successful surface functionalization process. This review emphasized the silane modification, such as improved mechanical properties of composites, enhanced electrical and thermal conductivity, functional coatings, water treatment, textile industries, catalysis, membrane applications, and biomedical applications, of various NMs. In particular, the role of silane-modified NMs in advancing energy harvesting technologies was highlighted, showcasing their potential to enhance the performance and stability of next-generation devices.
The green synthesis of zinc oxide nanoparticles (ZnO NPs) using Azadirachta indica (Neem) provides an eco-friendly and sustainable alternative to conventional chemical synthesis methods. This study investigates the optimization of key synthesis parameters,including temperature, pH, zinc precursor salt and reaction time, to achieve ZnO NPs with desirable physicochemical properties. Neem leaf extract being rich in bioactive phytochemicals, served as the reducing and stabilizing agent. The synthesized ZnO NPs were characterized using UV-visible spectrophotometry, Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM), measurements. Theoptimal synthesis conditions were found at 60°C, pH 8, using zinc acetate with a reaction time of 4 hours. Characterization results revealed that the ZnO NPs had an average size of 30-70 nm, with good stability and a narrow size distribution. The findings highlight the potential of Neem as a viable green resource for the synthesis of ZnO NPs, with implications for various biomedical and industrial applications.
Recently, attention has shifted towards the green synthesis of nanoparticles using plant extracts rich in phytochemicals like phenols and flavonoids, offering an alternative method that avoids harmful chemicals and enables large-scale, low-cost production. This study introduces a straightforward and eco-friendly approach to synthesizing hematite α-Fe2O3 nanoparticles utilizing an aqueous extract of Musa paradisiaca. The variation in the calcination temperature resulted in the formation of nanoparticles presented as Fe2O3 (1), Fe2O3 (2), and Fe2O3 (3), obtained at 650, 750, and 900 °C for 4 h, respectively. This variation allowed for an investigation into the impact of different reaction temperatures on the structural and optical properties of the nanoparticles. Structural analysis was conducted using X-ray diffraction (XRD), while scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to examine morphology. Optical properties were assessed via UV-vis spectroscopy, revealing a reduction in the energy band gap (from 2.5 to 1.87 eV), attributed to an increase in crystallite size resulting from longer calcination temperatures (650–900 °C). A biological assay was carried out to evaluate the antioxidant and anticancer potentials of the nanoparticles. Both Fe2O3 (1) and Fe2O3 (2) with IC50 values of 46.84 and 46.14 µg/mL, respectively, showed similar antioxidant potentials, while peel extract exhibited the least activity with an IC50 of 79.26 µg/mL. The nanoparticles, peels, and 5-FU (used as standard) showed a stronger inhibitory effect on the Human Embryonic Kidney (HEK) 293 cells compared to the HeLa cells. This implies that the HEK 293 cells might be more susceptible to the drug samples and a lower concentration might even be sufficient to achieve the inhibition of normal cell proliferation. These results indicate a better therapeutic window with a lesser inhibitory effect compared to standard drugs used as controls.
The increasing demand for cost-effective and sustainable advanced nanoparticles, particularly for agricultural applications, highlights the critical need for innovative solutions that support the agricultural growing area. This investigation introduces a novel eco-friendly fabrication technique for calcium oxide and magnesium oxide nanoparticles (CaO and MgO NPs) harnessing bioactive molecules in olive pomace waste as a reducing agent. After characterization, the CaO and MgO NPs clearly revealed their well-defined crystalline nature, with CaO exhibiting a cubic morphology and MgO a spherical morphology, with average diameters of 53 nm and 18 nm, respectively. The differential dose-dependent responses of CaO and MgO NPs on various soil microbiota demonstrated varying inhibitory and stimulatory species-specific growth effects. Moreover, the remarkable capacity of CaO and MgO NPs to significantly enhance seed germination and seedling growth across diverse crops, including Trigonella foenum-graecum, Solanum lycopersicum, and Triticum aestivum, was found to be concentration-dependent. Furthermore, results on seeds exposed to dual stress demonstrated that the nanoparticles exhibited notable biological activity in alleviating inhibitory effects at specific concentrations, suggesting their potential as a tool for stress management and the development of sustainable nanofertilizers.
A green, low-cost and reproducible Eclipta leaves negotiated synthesis of silver nanoparticles is reported. The synthesis is performed at room temperature. X-ray and transmission electron microscopy analyses are performed to ascertain the formation of Ag nanoparticles. Nanoparticles almost spherical in shape having a size of 2-6 nm are found. UV-visible study revealed the surface plasmon resonance at 419 nm. The lattice strain is estimated to be 0.0045 using Williamson-Hall approach. The use of Eclipta for the synthesis of silver nanoparticles offers the benefit of ecofriendliness and amenability for large scale production through scaling up.
Three categories of plants growing under three different extreme conditions were taken for assaying their promises to undertake nano-transformation. It was found that all of them successfully synthesize silver nanoparticles. The synthesis was performed akin to room temperature. X-ray and transmission electron microscopy analyses were performed to ascertain the formation of silver nanoparticles. X-ray analysis indicated that silver nanoparticles have FCC unit cell structure. Individual nanoparticles having the particle sizes of 2-5 nm were found. Possible involved mechanisms for the synthesis of silver nanoparticles from above plant systems have also been proposed.
Copper nanoparticles were biologically synthesized using plant leaf extract as reducing agent. On treatment of aqueous solution of CuSO4· 5H2O with Magnolia leaf extract, stable copper nanoparticles were formed. UV-vis spectroscopy was used to monitor the quantitative formation of copper nanoparticles. The synthesized nanoparticles were characterized with inductively coupled plasma spectrometry (ICP), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HR-TEM). Electron microscopy analysis of copper nanoparticles indicated that they ranged in size from 40 to 100 nm. Antibacterial tests were carried out by counting viable Escherichia coli cells after 24 h growth in shake flasks containing latex foams coated with copper nanoparticles. As a result, foams coated with biologically synthesized copper nanoparticles showed higher antibacterial activity compared with foams untreated. As possible ecofriendly alternatives to chemical and physical methods, biologically synthesized nanoparticles using plant extracts may have applications in various human body-contacting areas.
Development of nontoxic, clean techniques for the synthesis of metal nanoparticles such as gold has attracted increasing attention in recent years. Although many reports have been published about the biogenesis of gold nanoparticles using several plant extracts such as Neem leaf broth (Azadirachta indica), the capacity of a large number of such extracts to form gold nanoparticles has yet to be elucidated. In this research a titrimetric assay was employed for preliminary evaluation of the reducing potential of different medicinal plant extracts. All the extracts were used separately for the synthesis of gold nanoparticles through the reduction of aqueous AuCl 4-. After the screening step, the methanol extracts of Eucalyptus camaldulensis and Pelargonium roseum were selected for further studies. The reducing ability of these extracts was significantly enhanced as compared to Neem leaf broth (Azadirachta indica) which was used as control sample. Transmission electron microscopy, energy-dispersive spectroscopy and visible absorption spectroscopy confirmed the reduction of gold ions to gold nanoparticles. The E. camaldulensis and P. roseum extracts produced gold nanoparticles in the size ranges of 1.25-17.5 and 2.5-27.5 nm with an average size of 5.5 and 7.5 nm, respectively.
The synthesis of eco-friendly nanoparticles is evergreen branch of nanoscience for biomedical application. Low cost of synthesis and non toxicity are main features make it more attractive potential option for biomedical field and elsewhere. Here, we report the synthesis of gold nanoparticles in aqueous medium using Terminalia catappa (Almond) leaf extract as the reducing and stabilizing agent. On treating chloroauric acid solutions with Terminalia catappa (TC) leaf extract rapid reduction of chloroaurate ions is observed leading to the formation of highly stable gold nanoparticles in solution. TEM analysis of the gold nanoparticles indicated that they ranged in size from 10 to 35 nm with average size of 21.9 nm.
It has been almost 4 decades since the “war on cancer” was declared. It is now generally believed that personalized medicine is the future for cancer patient management. Possessing unprecedented potential for early detection, accurate diagnosis, and personalized treatment of cancer, nanoparticles have been extensively studied over the last decade. In this review, we will summarize the current state-of-the-art of gold nanoparticles in biomedical applications targeting cancer. Gold nanospheres, nanorods, nanoshells, nanocages, and surface enhanced Raman scattering nanoparticles will be discussed in detail regarding their uses in in vitro assays, ex vivo and in vivo imaging, cancer therapy, and drug delivery. Multifunctionality is the key feature of nanoparticle-based agents. Targeting ligands, imaging labels, therapeutic drugs, and other functionalities can all be integrated to allow for targeted molecular imaging and molecular therapy of cancer. Big strides have been made and many proof-of-principle studies have been successfully performed. The future looks brighter than ever yet many hurdles remain to be conquered. A multifunctional platform based on gold nanoparticles, with multiple receptor targeting, multimodality imaging, and multiple therapeutic entities, holds the promise for a “magic gold bullet” against cancer.
Small particles of Ti/Ni have been synthesized by a bioreduction method. The controlling parameter was the pH of the solution where they were grown in. HREM and high-angle annular dark field in the electron microscope have been used to characterize the morphology and structural properties of such small particles. Well controlled sizes in the range of 1–4 nanometers and with a structure based on an fcc-like geometry for the smallest clusters and with more complex arrays for larger clusters were obtained. In general it was demonstrated that the bimetal nanoparticles appear in a set of structures including the core-shell type, with Ni as the shell.
To formulate a simple rapid procedure for bioreduction of silver nanoparticles using aqueous leaves extract of Moringa oleifera (M. oleifera).
10 mL of leaf extract was mixed to 90 mL of 1 mM aqueous of AgNO3 and was heated at 60 - 80 °C for 20 min. A change from brown to reddish color was observed. Characterization using UV-Vis spectrophotometry, Transmission Electron Microscopy (TEM) was performed.
TEM showed the formation of silver nanoparticles with an average size of 57 nm.
M. oleifera demonstrates strong potential for synthesis of silver nanoparticles by rapid reduction of silver ions (Ag(+) to Ag(0)). Biological methods are good competents for the chemical procedures, which are eco-friendly and convenient.
The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60 meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by
Bunn [Proc. Phys. Soc. London 47, 836 (1935)
], studies of its vibrational properties with Raman scattering in 1966 by
Damen et al. [Phys. Rev. 142, 570 (1966)
], detailed optical studies in 1954 by
Mollwo [Z. Angew. Phys. 6, 257 (1954)
], and its growth by chemical-vapor transport in 1970 by
Galli and Coker [Appl. Phys. Lett. 16, 439 (1970)
]. In terms of devices, Au Schottky barriers in 1965 by
Mead [Phys. Lett. 18, 218 (1965)
], demonstration of light-emitting diodes (1967) by
Drapak [Semiconductors 2, 624 (1968)
], in which Cu2O was used as the p-type material, metal-insulator-semiconductor structures (1974) by
Minami et al. [Jpn. J. Appl. Phys. 13, 1475 (1974)
], ZnO/ZnSe n-p junctions (1975) by
Tsurkan et al. [Semiconductors 6, 1183 (1975)
], and Al/Au Ohmic contacts by
Brillson [J. Vac. Sci. Technol. 15, 1378 (1978)
] were attained. The main obstacle to the development of ZnO has been the lack of reproducible and low-resistivity p-type ZnO, as recently discussed by
Look and Claflin [Phys. Status Solidi B 241, 624 (2004)
]. While ZnO already has many industrial applications owing to its piezoelectric properties and band gap in the near ultraviolet, its applications to optoelectronic devices has not yet materialized due chiefly to the lack of p-type epitaxial layers. Very high quality what used to be called whiskers and platelets, the nomenclature for which gave way to nanostructures of late, have been prepared early on and used to deduce much of the principal properties of this material, particularly in terms of optical processes. The suggestion of attainment of p-type conductivity in the last few years has rekindled the long-time, albeit dormant, fervor of exploiting this material for optoelectronic applications. The attraction can simply be attributed to the large exciton binding energy of 60 meV of ZnO potentially paving the way for efficient room-temperature exciton-based emitters, and sharp transitions facilitating very low threshold semiconductor lasers. The field is also fueled by theoretical predictions and perhaps experimental confirmation of ferromagnetism at room temperature for potential spintronics applications. This review gives an in-depth discussion of the mechanical, chemical, electrical, and optical properties of ZnO in addition to the technological issues such as growth, defects, p-type doping, band-gap engineering, devices, and nanostructures.
An extremely simple green approach that generates bulk quantities of nanocrystals of noble
metals such as silver (Ag) and palladium (Pd) using coffee and tea extract at room temperature is
described. The single-pot method uses no surfactant, capping agent, and/or template. The
obtained nanoparticles are in the size range of 20–60 nm and crystallized in face centered cubic
symmetry. The method is general and may be extended to other noble metals such as gold (Au)
and platinum (Pt).
Microorganisms play an important role in toxic metal remediation through reduction of metal ions. Studies demonstrated that silver ions may be reduced extracellularly using Fusarium oxysporum to generate stable gold or silver nanoparticles in water. These particles can be incorporated in several kinds of materials such as cloths. These cloths with silver nanoparticles are sterile and can be useful in hospitals to prevent or to minimize infection with pathogenic bacteria such as Staphylococcus aureus. In this work, the extracellular production of silver nanoparticles by F. oxysporum and its antimicrobial effect when incorporated in cotton fabrics against S. aureus were studied. In addition, all effluent was bioremediated using treatment with C. violaceum. The results showed that cotton fabrics incorporated with silver nanoparticles displayed a significant antibacterial activity against S. aureus. The effluent derived from the process was treated with C. violaceum and exhibited an efficient reduction in the silver nanoparticles concentration. In conclusion, it was demonstrated the application of biological synthesis to silver nanoparticles production and its incorporation in cloths, providing them sterile properties. Moreover, to avoid any damage to the environment the effluent containing silver nanoparticles can be treated with cyanogenic bacterial strains.
A green, low-cost, and reproducible Cycas leaf-negotiated synthesis of silver nanoparticles is reported. X-ray and transmission electron microscopy (TEM) analyses are performed to ascertain the formation of Ag nanoparticles. Nanoparticles almost spherical in shape having the size of 2-6 nm are found. Rietveld analysis to the X-ray data indicated that Ag nanoparticles have fcc unit cell structure. Ultraviolet (UV)-visible study revealed the surface plasmon resonance at 449 nm. An effort has been made to understand the possible involved mechanism for the biosynthesis of Ag nanoparticles. Present procedure offers the benefit of eco-friendliness and amenability for large-scale production through scaling up.
The synthesis of nanocrystals is in the limelight in modern nanotechnology. Biosynthesis of nanoparticles by plant extracts is currently under exploitation. Not only could silver nanoparticles ranging from 55 to 80 nm in size be fabricated, but also triangular or spherical shaped gold nanoparticles could be easily modulated by reacting the novel sundried biomass of Cinnamomum camphora leaf with aqueous silver or gold precursors at ambient temperature. The marked difference of shape control between gold and silver nanoparticles was attributed to the comparative advantage of protective biomolecules and reductive biomolecules. The polyol components and the water-soluble heterocyclic components were mainly responsible for the reduction of silver ions or chloroaurate ions and the stabilization of the nanoparticles, respectively. The sundried leaf in this work was very suitable for simple synthesis of nanoparticles.
Development of biologically inspired experimental processes for the synthesis of nanoparticles is evolving into an important branch of nanotechnology. The present study deals with the synthesis of silver nanoparticles using Gliricidia sepium. On challenging, leaf broth of Gliricidia sepium and aqueous AgNO3 (1mM) solution changed from yellowish green to brown, the final color appeared gradually with time. The entire reaction mixture turned to brown color after 12 hrs of reaction, and exhibits an absorbance peak around 440 nm characteristic of Ag nanoparticle, its surface plasmon absorbance and due to different shapes of lone spherical or roughly spheri-cal Ag nanoparticles. Transmission electron microscopy (TEM) analysis showed silver nanoparticles which are polydispersed and ranged in size from 10-50 nm with an average size of 27 nm, the particles were predominantly spherical. X-ray diffraction (XRD) studies reveals a number of Braggs reflections that may be indexed on the basis of the face centered cubic structure of silver nanoparticle and Fourier Transform Infrared Spectroscopy (FTIR) analysis, which showed that silver nanoparticles are capped. Phytosynthesized silver nanoparti-cles show the antibacterial activity against the Staphylococcus aureus ATCC 6538P, Escherichia coli ATCC 8739, Pseudomonas aerugi-nosa ATCC 9027 and Klebsiella pneumoniae (clinical isolate). The approach of phytosynthesis appears to be cost efficient eco-friendly and easy alternative to conventional methods of silver nanoparticles synthesis.
There is an increasing commercial demand for nanoparticles due to their wide applicability in various areas such as electronics, catalysis, chemistry, energy and medicine. Metallic nanoparticles are traditionally synthesized by wet chemical techniques, where the chemicals used are quite often toxic and flammable. In this research article we present a simple and eco-friendly biosynthesis of silver nanoparticles using Garcinia mangostana leaf extract as reducing agent. The aqueous silver ions when exposed to leaf extract were reduced and resulted in silver nanoparticles whose average size was 35 nm. The silver nanoparticles were characterized by UV–Visible, Fourier transform infra-red spectroscopy (FT-IR) and transmission electron microscopy (TEM) techniques. Furthermore these biologically synthesized nanoparticles were found to be highly effective against different multi-drug resistant human pathogens.
Nanotechnology is the ability to build and shape matter one atom at a time. Modern cells provide us with an elaborate, efficient set of molecular machines that restructure matter atom-by-atom, exactly to our specifications. Using these natural nanomachines, and building upon the nanoscale principles of their operation, nanotechnology is a reality today, and is accessible with remarkably modest resources.
Biosynthesis of Ag nanoparticles (AgNPs) by Cacumen Platycladi extract was investigated. The AgNPs were characterized by ultraviolet–visible absorption spectroscopy (UV–vis), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and X-ray diffraction (XRD). The results showed that increasing the initial AgNO3 concentration at 30 or 60 °C increased the mean size and widened the size distribution of the AgNPs leading to red shift and broadening of the Surface Plasmon Resonance absorption. The conversion of silver ions was determined by atomic absorption spectroscopy (AAS) and to discuss the bioreductive mechanism, the reducing sugar, flavonoid, saccharide, protein contents in the extract, and the antioxidant activity were measured using 3,5-dinitrosalicylic acid colorimetric; Coomassie brilliant blue; phenol-sulfuric acid; rutin-based spectrophotometry method; and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging assay methods. The results showed that the reducing sugars and flavonoids were mainly responsible for the bioreduction of the silver ions and their reductive capability promoted at 90 °C, leading to the formation of AgNPs (18.4 ± 4.6 nm) with narrow size distribution. Finally, the antibacterial activity of the AgNPs against E. coli and S. aureus was assessed to determine their potential applications in silver-loaded antibacterial materials. This work provides useful technical parameters for industrialization of the biosynthetic technique and further antibacterial application of the AgNPs. Furthermore, the elucidation of bioreductive mechanism of silver ions by measuring the change of the biomolecular concentrations in plant extract exemplifies understanding the formation mechanism of such biogenic AgNPs.
Single-crystalline indium oxide (In2O3) nanocubes were successfully prepared via dehydration of indium hydroxide (In(OH)3) nanocubes synthesized by a hydrothermal method. In situ x-ray diffraction patterns of the phase transition were obtained. Transmission electron microscopy indicated that the morphology of the In2O3 nanocrystallites was the same as that of their precursors, In(OH)3 nanocrystallites. The reported method, the dehydration of In(OH)3 nanocrystallites prepared by a hydrothermal method, shows a simple and effective synthesis route for In2O3 nanostructured materials.
In this study, a simple method to prepare carboxylate-modified Pd nanoparticles has been built by stirring the mixture of CNCH2COOK and PdCl42− solution. The results suggest that the Na2PdCl4/CNCH2COOK (mole/mole) ratio of 1:2 is helpful in the reduction of Pd2+ to Pd0. Here, CNCH2COOK not only works as reducing agent instead of the conventional NaBH4 and N2H4·H2O to reduce Pd2+, but also as stabilizer to effectively stabilize Pd nanoparticles. In addition, the possible reaction mechanism was proposed by assumption that isocyanide group is responsible for the reduction of PdCl42− and the carboxyl group and its synergism with –NC group are helpful to the reaction.
Bayberry tannin (BT), a natural plant polyphenol, is used for the one-step synthesis of Au@Pd core–shell nanoparticles (Au@Pd NPs) in aqueous solution at room temperature. Due to its mild and stepwise reduction ability, BT was able to preferentially reduce Au3+ to Au NPs when placed in contact with an Au3+/Pd2+ mixture, and subsequently, the formed Au NPs served as in situ seeds for the growth of a Pd shell, resulting in the formation of Au@Pd NPs. Importantly, it is feasible to adjust the morphology of the Pd shell by varying the Pd2+/Au3+ molar ratio. Au@Pd NPs with a spherical Pd shell were formed when the Pd2+/Au3+ molar ratio was 1/50, while Au@Pd NPs with cubic Pd shell predominated when the ratio was increased to 2/1. The core–shell structure of synthesized Au@Pd NPs was characterized by TEM, HAADF-STEM, EDS mapping, an EDS line scan, and EDS point scan. Furthermore, density functional theory (DFT) calculations suggested that the localization of BT molecules on the surface of the Auclusters was the crucial factor for the formation of Au@Pd NPs, since the BT molecules increased the surface negative charges of the Au NPs, favoring the attraction of Pd2+ over Au NPs and resulting in the formation of a Pd shell.
In this study, the bio-reduction of Au(III) to Au(0) by wheat biomass and the subsequent production of gold nanoparticles of various shapes and sizes is presented. The dry biomass was ground and sieved in order to assure a uniform particle size and having more area of biomass exposed to the gold. Wheat biomass was exposed to a 0.3mM potassium tetrachloroaurate solution at pH values of 2, 3, 4, 5, and 6 for three and a half hours at room temperature. After that time, the biomass pellets were analyzed using a high resolution transmission electron microscope, JEOL-4000 EX, in order to characterize the gold nanoparticles. The results showed that wheat biomass produced nanostructures of the following morphologies: Fcc tetrahedral (T), decahedral (Dh), hexagonal (He), icosahedral multitwinned (I), irregular shape (Irr), and rod shape nanoparticles. The highest percent of the nanoparticles formed had a particle size ranging from 10-30 nm.
Nanoparticles are a state of matter that has properties different from either molecules or bulk solids. In the present work, we review the shape and structure of nanometer-sized particles; several shapes are discussed, such as the octahedron and truncated octahedron, the icosahedron, the Marks decahedron, the truncated “star-like” decahedron, the rounded decahedron and the regular decahedron. Experimental high-resolution transmission electron microscopy (TEM) images of each type of particle are presented together with the Fast Fourier Transform and a model of the particle. We consider only gold particles grown by vapor deposition or by colloidal methods. High-resolution TEM images of the particles in different orientations are shown. We discuss two basic types of particles uncapped and capped. Data for other metals and semiconductors are reviewed. We have also performed very extensive simulations obtaining the total energy and pair correlation functions for each cluster under study. Furthermore, distributions of single atom energy for every cluster are displayed in order to reveal the effect of surface on the stability of different types and sizes of clusters. We discuss the structure of the particles from ∼1 to ∼100 nm. The mechanisms for stress release as the particles grow larger are reviewed and a mechanism is suggested. Finally, we discuss the parameters that define the shape of a nanoparticle and the possible implications in technological applications. © 2001 American Vacuum Society.
Existing technologies for the extraction and recovery of gold include cyanidation which uses toxic cyanide. Because of the potential health threat created by many of these processes, an increasing need to develop new safer technologies to extract and recover gold from aqueous solution has arisen. Previous experiments have shown that gold(III) is adsorbed by alfalfa biomass at high concentrations in an almost pH-independent manner. However, little data exist for the bio-adsorption of trace levels of gold(III) by alfalfa biomass. Batch laboratory pH profile experiments were performed at trace levels with native alfalfa biomass using a 100 ppb gold(III) aqueous solution. The observed trend in the binding by the alfalfa biomass was highest at pH 2–3 (≈97%) and decreased to approximately 50% at pH 4.0 and 5.0. To explore the effects of hard cations on the trace level gold(III) binding, calcium, magnesium, and sodium cations were added to the gold(III) solutions and binding experiments were repeated to determine how these ions might interfere with the gold(III) bio-adsorption by the biomass. Experiments were also performed using all three cations combined in solution to further explore the effects of hard cations on the trace level gold(III) binding to the alfalfa biomass. All of the interference experiments showed that under optimal conditions the presence of the hard cations in concentrations as high as 3000 times the ppm concentration of gold(III) did not greatly effect binding by the alfalfa biomass.
A facile bottom–up “green” synthetic route using green tea (Camellia sinensis) extract as reducing and stabilizing agent produced gold nanoparticles and silver nanostructures in aqueous solution at ambient conditions. Colloidal systems of silver and gold nanoparticles exhibit highly efficient single photon-induced luminescence. This optical response can be manipulated by changing concentrations of metal ions and the quantity of reducing agent, which plays a crucial role in formation, growth and luminescence response of these noble-metal nanostructures.
Is a Distinguished Professor of Chemistry at Syracuse University, New York, USA. He received his B. Sc. from the University of Leicester (England) and his Ph.D. and D.Sc. from the University of London. He has utilized surfactant assemblies-aqueous and reversed micelles, Langmuir monolayers, Langmuir–Blodgett films, vesicles andpolymerized vesicles, and bilayer lipid membranes–for molecular organization and compartmentalization. His research has been reported in more that 250 primary publications and summarized in 50 review articles and three books. He has received several awards, including the Langmuir Distinguished Lecturer Award and the ACS National Award in Colloid or Surface Chemistry.
The size and shape dependent electronic and chemical properties of metal nanoparticles has drawn the attention of chemists, physicists, biologists, and engineers who wish to use them for the development of new generation nanodevices. In this article, we report the synthesis of gold nanotriangles using tamarind leaf extract as the reducing agent. On treating aqueous chloroauric acid solution with tamarind leaf extract, rapid reduction of the chloroaurate ions is observed leading to the formation of flat and thin single crystalline gold nanotriangles. Atomic force microscopy analysis of the gold nanotriangles indicated that they ranged in thickness from 20 to 40 nm. These gold nanotriangles with unique and highly anisotropic planer shapes might find application in photonics, optoelectronics, and optical sensing. We investigated the effect of different organic solvent vapors like methanol, benzene and acetone on the conductivity of tamarind leaf extract reduced gold nanotriangles. I‐V characteristics measurement of these nanotriangles was done in presence of these organic solvent vapors. The observed characteristics suggest the application of gold nanotriangles to future chemical sensors.BA thanks the Indian Academy of Sciences, Bangalore for a Summer Fellowship. BA and MC thank the Director, National Chemical Laboratory (NCL), Pune for permission to carry out this research at NCL.
Palladium nanoparticles with narrow size distribution were prepared by applying poly(ethyleneglycol) (PEG) and Pd(OAc)2 in the absence of other chemical agents. PEG appeared to act as both reducing agent and stabilizer. The results of XRD show that the concentration of precursor played the key role to the development of palladium nanoparticles. The reduction of Pd2+ to nano Pd was sensitive to the chain length of the PEG, and the larger chain length PEG such as PEG 2000 exhibited higher reduction reactivity. The as-prepared palladium nanoparticles were found to be a highly stable and reusable catalyst for Heck reaction.
This paper reports a facile and rapid biosynthesis of silver and gold nanoparticles from Chenopodium album, an obnoxious weed. The aqueous leaf extract of the herb was used as mild reducing agent for silver and gold nanoparticles (SNPs and GNPs) synthesis from their salt solutions in single-pot process. Quasi-spherical shapes were observed for biosynthesized SNPs and GNPs within range of 10–30nm, respectively. The UV–VIS spectra gave surface plasmon resonance (SPR) for SNPs and GNPs at 460 and 540nm, respectively. Influence of leaf extract quantities, metal concentrations, contact time, reaction temperature and pH were evaluated to find their effects on NPs synthesis. The produced nanocrystals of silver and gold were analyzed with transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray (EDX) and fourier transform infrared spectroscopy (FTIR). The stability of NPs was evaluated at different pH with zeta potentiometer without adding any stabilizing agents.
ELECTROLUMINESCENT devices have been developed recently that are based on new materials such as porous silicon1 and semiconducting polymers2,3. By taking advantage of developments in the preparation and characterization of direct-gap semiconductor nanocrystals4-6, and of electroluminescent polymers7, we have now constructed a hybrid organic/inorganic electroluminescent device. Light emission arises from the recombination of holes injected into a layer of semiconducting p-paraphenylene vinylene (PPV)8-10 with electrons injected into a multilayer film of cadmium selenide nanocrystals. Close matching of the emitting layer of nanocrystals with the work function of the metal contact leads to an operating voltage11 of only 4V. At low voltages emission from the CdSe layer occurs. Because of the quantum size effect19-24 the colour of this emission can be varied from red to yellow by changing the nanocrystal size. At higher voltages green emission from the polymer layer predominates. Thus this device has a degree of voltage tunability of colour.
Silver, palladium, and silver–palladium nanoparticles have been prepared by reduction of silver acetylacetonate and palladium acetate with dimethylamine–borane in the presence of a fluorinated surfactant (FOMBLIN HC/P2-1000) in supercritical carbon dioxide. The sizes of silver and palladium nanoparticles increases with increasing concentrations of both the soluble precursors and FOMBLIN. The size of silver nanoparticles obtained is 3–12 nm, while that of palladium nanoparticles is 3–6 nm. For preparation of silver–palladium nanoparticles, the particle size is ranged between 4 and 5 nm and dependent on the feed molar ratio of palladium acetate. It is found that silver–palladium nanoparticles consist of a core-shell structure with enriched palladium in the surface.
The quantum confinement effects and electronic properties in zero dimensional semiconductor microcrystallite systems were reviewed. The increase in energy of excitation peaks with the reduction in the radius of the microcrystallite was examined. The energy of the excited states was derived in terms of bulk energy gap, kinetic energy, Coulomb energy and correlation energy. Two other topics discussed include biexciton formation by the use of high intensity laser beams and nonlinear optical effects.
Silver nanoparticles (NPs) were rapidly synthesized by treating silver ions with a Capsicum annuum L. extract. The reaction process was simple and convenient to handle, and was monitored using ultraviolet-visible spectroscopy (UV-vis). The effect of Capsicum annuum L. proteins on the formation of silver NPs was investigated using X-ray photoemission spectroscopy (XPS), electrochemical measurements, Fourier-transform infrared spectroscopy (FTIR) and differential spectrum techniques. The morphology and crystalline phase of the NPs were determined from transmission electron microscopy (TEM), selected area electron diffraction (SAED) and X-ray diffraction (XRD) spectra. The results indicated that the proteins, which have amine groups, played a reducing and controlling role during the formation of silver NPs in the solutions, and that the secondary structure of the proteins changed after reaction with silver ions. The crystalline phase of the NPs changed from polycrystalline to single crystalline and increased in size with increasing reaction time. A recognition–reduction–limited nucleation and growth model was suggested to explain the possible formation mechanism of silver NPs in Capsicum annuum L. extract.
Development of environmental friendly procedures for the synthesis of metal nanoparticles through biological process is evolving into an important branch of nanobiotechnology. Generally, nanoparticles are synthesized by chemical and physical methods, which are not eco-friendly. In this paper, we report the fabrication of silver nanoparticles (NPs) and discuss the possible mechanism involved. Silver nanoparticles were rapidly synthesized by challenging silver ions with leaf extract of Datura metel. The reaction process is rapid, simple and easy to handle. The UV-Vis spectrum of aqueous medium containing silver nanoparticles showed peak at 420 nm corresponding to plasmon absorbance of silver nanoparticles. Transmission electron microscopic analysis of the silver nanoparticles indicated that they ranged in size from 16 to 40 nm and were assembled in solution into quasilinear superstructures. X-ray EDS analysis confirmed that Ag constituted the nanoparticles. It is assumed that alcoholic component (plastohydroquinone or plastrocohydroquinol) present in leaf extract is mainly responsible for reduction of silver ions thus indicating a possible mechanism of synthesis of silver nanoparticles by D. metel.
In modern nanotechnology one of the most exciting areas is the interaction between inorganic quantum dots and biological structures. For instance gold clusters surrounded by a shell of organic ligands covalently attach to proteins or other biological substances and can be used for labeling in structural biology. In the present report we show the possibility of using live plants for the fabrication of nanoparticles. Alfalfa plants were grown in an AuCl4 rich environment. The absorption of Au metal by the plants was confirmed by X-ray absorption studies (XAS), and transmission electron microscopy (TEM). Atomic resolution analysis confirmed the nucleation and growth of Au nanoparticles inside the plant and that the Au nanoparticles are in a crystalline state. Images also showed defects such as twins in the crystal structure, and in some cases icosahedral nanoparticles were found. X-ray EDS studies corroborated that the nanoparticles are pure gold. This is the first report on the formation of gold nanoparticles by living plants and opens up new and exciting ways to fabricate nanoparticles. It shows how it is possible to link materials science and biotechnology in the new emerging field of nanobiotechnology.
Dye reduction catalyzed by palladium nanoparticles has been investigated in water and surfactant media. The initial rate of dye reduction strongly depends on the nature of the reducing agent and dye. In most cases the rate becomes surface controlled and depends on the E1/2 values of the dye and the reducing agent. However, stronger reducing agents make the reduction process a diffusion controlled one. A detailed study has been carried out to understand the effect of surfactant on the reaction rate. A variation of the reaction rates has been observed in surfactants above and below the critical micelle concentration (cmc). Below the cmc, surfactants are adsorbed onto the Pd surface and act as a binding site for both the dye and the reducing agent. Above the cmc, surfactants form micelles which provide additional binding sites. Catalytic selectivity was also achieved by proper selection of reducing agent and surfactant.
The preparation and study of quantum dots and quantum wires play a very important role in nanotechnology. In this particular study, we report on the uptake of silver by living alfalfa plants. X-ray absorption spectroscopy and transmission electron microscopy (TEM) studies corroborated silver metal uptake by alfalfa plants from a silver-rich solid medium and the subsequent formation of silver nanoparticles. Silver nanoparticle alignment, structure, and coalescence were observed using TEM with an atomic resolution analysis. Dark field image TEM showed the connection of silver nanoparticles of different sizes by possibly noncrystalline silver atomic wires. To our knowledge, this is the first report on the formation of silver nanoparticles by a living plant system.
The optical properties of metal nanoparticles have long been of interest in physical chemistry, starting with Faraday's investigations of colloidal gold in the middle 1800s. More recently, new lithographic techniques as well as improvements to classical wet chemistry methods have made it possible to synthesize noble metal nanoparticles with a wide range of sizes, shapes, and dielectric environments. In this feature article, we describe recent progress in the theory of nanoparticle optical properties, particularly methods for solving Maxwell's equations for light scattering from particles of arbitrary shape in a complex environment. Included is a description of the qualitative features of dipole and quadrupole plasmon resonances for spherical particles; a discussion of analytical and numerical methods for calculating extinction and scattering cross-sections, local fields, and other optical properties for nonspherical particles; and a survey of applications to problems of recent interest involving triangular silver particles and related shapes.
Q-sized CdS semiconductors have been synthesized in several nonaqueous solvents without the use of added stabilizers. The effects of solvent viscosity and dielectric strength, concentration of excess cadmium ions, temperature, and stirring upon the colloids' absorption spectra have been examined. In addition, efficiency of photoinitiation of polymerization of several vinylic monomers has been examined using both bulk and quantum-sized CdS, ZnO, and TiO2. The Q-sized semiconductors demonstrated significantly higher quantum yields for photopolymerization than their bulk-sized counterparts. A correlation between the reactivity of a monomer toward polymerization and its Alfrey and Price Q and e values was observed. Hole scavenging by the solvent was necessary for efficient polymerization to occur. A correlation between the semiconductor photoinitation efficiency, and the reduction potential of its conduction band electrons was also found. On the basis of these observations, a mechanism of an anionic initiation step followed by free radical chain propagation steps has been proposed.
Recent advances in the synthesis of semiconductor clusters open a doorway for the systematic study of size-dependent cluster properties in the condensed phase. This article focuses on the size effect on the optical and photophysical properties. The authors first introduce fundamental concepts and proceed to a discussion of recent progress toward the understanding of the quantum size effect and dielectric confinement effect. They then discuss the current status of materials synthesis and the prospect for making monodisperse clusters of well-defined surfaces.
The mean diameter of monodispersed Pd nanoparticles could be controlled from 17 to 30 Å in a one-step reaction by changing the amount of protective polymer, poly(N-vinyl-2-pyrrolidone) (PVP) and the kind and/or the concentration of alcohol in the solvent. Although increasing the amount of protective polymer made the size of Pd nanoparticles smaller, the particle size appeared to have a lower limit determined by the kind of alcohol. On the other hand, monodispersed Pd nanoparticles of smaller diameter were obtained in the order methanol > ethanol > 1-propanol, indicating that a faster reduction rate of [PdCl4]2- ions is an important factor to produce the smaller particles. The particle diameter showed a minimum at around 40 vol % of alcohol in solvent. Once the monodispersed Pd nanoparticles were obtained, the larger particles with a narrow size distribution could be easily synthesized by using the stepwise growth reaction. The Pd nanoparticles obtained here had fcc structures like that of bulk Pd, although the lattice constant increased with a decrease in the particle size.
We describe the formation of amorphous selenium (α-Se)/protein composites using Capsicum annuum L extract to reduce selenium ions (SeO32−) at room temperature. The reaction occurs rapidly and the process is simple and easy to handle. A protein with a molecular weight of 30 kDa extracted from Capsicum annuum L not only reduces the SeO32− ions to Se0, but also controls the nucleation and growth of Se0, and even participates in the formation of α-Se/protein composites. The size and shell thickness of the α-Se/protein composites increases with high Capsicum annuum L extract concentration, and decreases with low reaction solution pH. The results suggest that this eco-friendly, biogenic synthesis strategy could be widely used for preparing inorganic/organic biocomposites. In addition, we also discuss the possible mechanism of the reduction of SeO32− ions by Capsicum annuum L extract.
Palladium nanoparticles with low polydispersity were fabricated by thermally-induced reduction of
Pd(fod)2 in
o-xylene in the presence of tetraalkylammonium salts as the surfactants. The particle size,
ranging from 6.2 to 18.5 nm, can be controlled by variation of the surfactant, and the
concentrations of precursor and surfactant. Self-assembly of the Pd nanoparticles in closest
packing was observed in this study.
The photoelectrochemical (PEC) characteristics of thin films of ‘Q-state’ CdS semiconductor particles in arachidic acid Langmuir–Blodgett (LB) layers have been examined. Initially, ‘Q-state’ size CdS particles of ca. 2 nm were formed in the film and then progressively grown to ca. 10 nm by a cyclic sequence, which involves exposing the film to H2S(g) following its immersion in a CdCl2(aq) solution. A PEC cell was constructed using a layered glass/ITO–CdS/LB plate as the photoanode and a standard calomel electrode (SCE) as the reference electrode. The photoelectrical response of electrodes coated with LB films containing CdS particles of various sizes was investigated using white light. The reproducibility of current–voltage polarisation curves indicated the relatively good stability of the film to PEC degradation processes over several scanning cycles in the range 0 to –1000 mV vs. SCE. Values for the open-circuit (Voc) and the short-circuit current for the PEC cells were obtained and fill factors in the range 20 to 70–75% were calculated. Voc decreased from ca. –200 to ca. –800 mV vs. SCE with increasing particle size. This effect was attributed to the dielectric properties of the arachidic acid LB film matrix.
Nanobiotechnology is a key enabling multidisciplinary field for medical, technological and biological research and development, medicine, pharmaceutical development, and analytical sciences. Its foundation is the selective integration of a multitude of endeavours, such as biotechnology, chemical and physical nanotechnology, materials sciences, chemistry, engineering, electronics and optronics targeting the construction of micro- and nano-arrays for analyzing complex mixtures of DNA, RNA, proteins, metabolites as well as the design of ultra-sequencing devices, microbial fuel cells, implantates, molecular motors, artificial organs, and nanorobots. The developments in nanobiotechnology benefit from and contribute to the scientific advances in the chemical and physical nanotechnologies, in particular with respect to materials, composites, nanostructuring techniques, carbon nanotubes, and nanoelectronics.