Fabrication Of Metal Nanoparticles Research Articles

Metallic Nanostructures: An Updated Review on Synthesis, Stability, Safety, and Applications with Tremendous Multifunctional Opportunities.

Metallic nanostructures play a vital role in technological advancement, providing exceptional performance and improved adaptability in comparison to their bulk equivalents. Conventional synthesis techniques frequently depend on dangerous reducing agents to transform metal ions into Nanoparticles (NPs), which presents considerable environmental and health issues. In contrast, the approach of green synthesis, which emphasizes the use of non-toxic reagents, has garnered significant interest as a sustainable method for the fabrication of Metallic Nanoparticles (MNPs). This sustainable approach utilizes biological sources, like actinomycetes, algae, fungi, polymers, crops, waste biomass, and yeast, recognized for their excellent biocompatibility, availability, affordability, and efficiency. Biological extracts act as reducing and stabilizing agents, with the metabolites and enzymes present in these extracts aiding in the conversion of metal ions into nanoparticles. This review offers an in-depth examination of different MNPs, such as copper, gold, platinum, silver, and zinc, emphasizing their distinct characteristics and a variety of synthesis methods. The review further explores the diverse applications of MNPs in biomimetics, agriculture, and various industrial sectors, including energy, catalysis, and wastewater treatment, along with optical enhancement. This review explores stability and toxicity profiles, filling a significant gap in the existing knowledge base and providing valuable insights into the broad applicability of MNPs.

Plant-Derived Natural Products and Their Nano Transformation: A Sustainable Option Towards Desert Locust Infestations.

The desert locust has been recognized as the most devastating migratory pest in the world. Swarms of this pest have been threatening vast regions of pastures and crops in Africa, Middle East, and South Asia. The biological management of expanding swarms has become a strategy of particular interest due to environmental awareness and economic issues associated with chemical pesticides. The present review aims to explore the latest updates and information about pesticidal plants that are distributed across Africa. Searches on Web of Science, Google Scholar, PubMed, and Scopus databases from 2013-2024 revealed a total of 22 plant species probed for insecticidal activities against desert locusts. The formulation, active ingredients, and biological effects of essential oils and other extracts from these plants are presented. Despite the promising anti-insecticidal effects of the plant extracts and compounds, issues related to their solubility and instability under environmental conditions have been observed. To address such major quality defects, methods for the encapsulation of plant natural products within nanostructures are detailed. Given the presence of bioactive compounds with nucleophiles bearing functional groups, the reported plant extracts have been exploited to fabricate metal nanoparticles with inherent insecticidal activities. In this paper, a holistic overview of prepared phytochemical-coated metal nanopesticides is also presented. In summary, this study offers insights into the integration of nanoformulated natural resources as a more sustainable option to control desert locust invasions.

Eco-Friendly Fabrication of Metal Nanoparticles with Enhanced Antimicrobial and Anticancer Properties

Eco-Friendly Fabrication of Metal Nanoparticles with Enhanced Antimicrobial and Anticancer Properties

Metal nanoparticles loaded polyurethane nano-composites and their catalytic/antimicrobial applications: a critical review

Abstract Polyurethane (PU) belongs to a unique class of polymers. Different properties of PU such as mechanical strength and biocompatibility can be enhanced by co-polymerizing it with different bio and synthetic polymers. It finds huge applications as micro-reactors for the fabrication of metal nanoparticles (MNPs) owing to the synergistic properties of both polyurethane and fabricated metal nanoparticles. Metal nanoparticles fabricated polyurethane have gained much attention in the last few years. These types of nanocomposites hyphenate the mechanical properties of polyurethane with the high surface-to-volume ratio of metal nanoparticles. Here, this review article briefly evaluates different methods of synthesis of polyurethane-based metal nanocomposites and their characterization via different techniques to evaluate their properties. Applications of these polyurethane based nanocomposite materials have also been described critically in different fields depending upon their catalytic, antimicrobial and antifungal potential. Future directions of these nanocomposite materials have also been described in the field of designing of nano-filters and nano-devices in order to attain environmental remediation and sustainability.

FABRICATION OF NANOSTRUCTURED IRON AND ZINC PARTICLES BY DIOSPYROS CHLOROXYLON (ROXB.) LEAF EXTRACT: CHARACTERIZATION, ADSORPTION MODELING AND CARCINOGENIC DYE ADSORPTION APPLICATIONS

Objective: The discharge of these synthetic food dyes, such as sunset yellow and tartrazine, into industrial wastewater can lead to significant environmental and health issues. Its removal through effective adsorption presents an economical and efficient solution. Hence this study proposed to fabricate metal nanoparticles for the adsorption of carcinogenic dyes. Methods: The fabrication of iron and zinc nanoparticles employed the green synthesis methodology, utilizing an aqueous extract of Diospyros chloroxylon (Roxb.) as a reducing agent. The fabricated nanoparticles were characterized using TEM (Transmission Electron Microscopy), EDX (Energy-Dispersive X-ray Spectroscopy), SEM (Scanning Electron Microscopy), FTIR (Fourier-Transform Infrared Spectroscopy), and UV-Visible Spectroscopy. The nanoparticles were studied for its efficiency for the adsorption of carcinogenic dyes such as tartrazine and Sunset Yellow. Results: The iron nanoparticles were noticed to be uniformly distributed rod-shaped particles having smooth surfaces with 23-51 nm size range and an average particle size of 34 nm. Whereas the iron nanoparticles were noticed to be uniformly distributed spherical to oval shape with 35 nm to 68 nm size range and an average particle size 53 nm. The XRD results confirm that the iron nanoparticles were rhombohedral phase structure with 71.91 % of elemental iron whereas the zinc nanoparticles were noticed to be hexagonal Wurtzite phase structure having 69.4 % of metallic zinc. These synthesized nanoparticles were applied for the removal of sunset yellow and tartrazine dyes were investigated and found more than 90 % was removed. Adsorption isotherm study was best fitted with Langmuir model, and the maximal adsorption capacity was found to be 52.18 and 75.04 mg/g for sunset yellow using iron and zinc nanoparticles, whereas tartrazine maximum adsorption capacity was noticed to be 69.96 and 84.24 mg/g for iron and zinc nanoparticles. The adsorption reaction follows pseudo-first-order kinetics with high correlation coefficient. Repeated cycles of regeneration, reuse and stability showed very high removal efficiency and stability. Conclusion: The biosynthesis of metal nanoparticles demonstrates substantial promise for applications in environmental protection.

Phytonanofabrication of Copper Oxide from Albizia saman and Its Potential as an Antimicrobial Agent and Remediation of Congo Red Dye from Wastewater

Metal nanoparticle fabrication through plant-based green methods is considered the gold standard among the various synthesis techniques owing to its simplicity, eco-friendliness, ease of use, and the huge diversity of plant species. Copper nanoparticles (CuONPs) have proven their potential in the fields of medicine, agriculture, pharmaceutics, and catalysis, and are being synthesized using various physicochemical and biological methods. Here, the authors have reported on the first-ever use of Albizia saman leaf extract for the development of CuONPs. Phytochemical analysis of the methanolic extracts of the plant exhibited the presence of phenols (32.31%), tannins (12.27%), and flavonoids (16.72%). The phytonutrients existing in leaf extract successfully reduced the copper salt in the CuONPs. A detailed investigation of the synthesized CuONPs was performed using advanced instruments. The UV-Vis spectra exhibited an absorbance peak at 290 nm, while the X-ray diffraction pattern (XRD) revealed that the average crystallite size was about 29.86 nm. Dynamic light scattering (DLS) revealed that the average hydrodynamic size of the CuONPs was 72.3 nm in diameter, while its zeta potential was −0.49, with a negative polarity. Fourier transform infrared spectroscopy showed the major bands in the region of 400 to 1000 cm−1, suggesting the formation of CuONPs, while the band in the region of 1100 to 2600 cm−1 shows the association of plant molecules with the phytonanofabricated CuO particles. Transmission and scanning electron microscopy showed the spherical shape of the CuONPs, whose size was about 20–50 nm. The phytonanofabricated CuO exhibited antibacterial activity by forming a zone of inhibition (ZOI) against Escherichia coli, Staphylococcus aureus, and Candida albicans. The removal efficiency of the CuONPs was 33.33% for Congo Red dye. The removal efficiency of the phytonanofabricated CuO for CR dye was reduced to 16% after the 4th cycle.

Innovative Preparation of Cellulose-Mediated Silver Nanoparticles for Multipurpose Applications: Experiment and Molecular Docking Studies.

In recent years, inorganic metal nanoparticle fabrication by extraction of a different part of the plant has been gaining more importance. In this research, cellulose-mediated Ag nanoparticles (cellulose/Ag NPs) with excellent antibacterial and antioxidant properties and photocatalytic activity have been synthesized by the microwave-assisted hydrothermal method. This method is a green, simple, and low-cost method that does not use any other capping or reducing agents. X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission scanning microscopy (FESEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), and UV-visible spectroscopic techniques were used to investigate the structure, morphology, as well as components of the generated cellulose/Ag NPs. In fact, XRD results confirm the formation of the face-centered cubic phase of Ag nanoparticles, while the FTIR spectra showed that the synergy of carbohydrates and proteins is responsible for the formation of cellulose/Ag NPs by the green method. It was found that the green-synthesized silver nanoparticles showed good crystallinity and a size range of about 20-30 nm. The morphology results showed that cellulose has a cavity-like structure and the green-synthesized Ag NPs were dispersed throughout the cellulose polymer matrix. In comparison to cellulose/Ag NPs and Ag nanoparticles, cellulose/Ag NPs demonstrated excellent antibacterial activity, Proteus mirabilis (MTCC 1771) possessed a maximum inhibition zone of 18.81.5 mm at 2.5 g/mL, and Staphylococcus aureus (MTTC 3615) had a minimum inhibition zone of 11.30.5 mm at 0.5 g/mL. Furthermore, cellulose/Ag NPs also exhibited a significant radical scavenging property against the DDPH free radical, and there was a higher degradation efficiency compared to pure Ag NPs against Rhodamine B as 97.38% removal was achieved. Notably, cellulose/Ag NPs remarkably promoted the transfer and separation of photogenerated electron-hole (e-/h+) pairs, thereby offering prospective application of the photodegradation efficiency for Rhodamine B (RhB) as well as antibacterial applications. With the findings from this study, we could develop efficient and environmentally friendly cellulose/Ag nanoparticles using low-cost, environmentally friendly materials, making them suitable for industrial and technological applications.

Recyclable surface-enhanced Raman spectroscopy (SERS) platform fabricated with Ag-decorated ZnSe nanowires and metamaterial

In surface-enhanced Raman scattering (SERS), metal-semiconductor heterostructures have attracted a lot of interest because of their remarkable features. However, the use of organic substances in the fabrication of metal nanoparticles can result in contamination of the SERS substrate, which can negatively impact sensor performance. Here, we introduced new recyclable SERS substrates which include Ag-decorated ZnSe nanowires and hyperbolic metamaterial. The Ag-decorated ZnSe nanowires work as an external coupling structure for hyperbolic metamaterials, due to this structure exhibiting significant plasmonic effects as well as unique optical features. There exists overlapping and physical interaction between metal and semiconductor nanowires, as a result, both resonance energy and hot electron were transferred. Rhodamine 6G (R6G), malachite green (MG), and adenosine were used to assess the SERS performance of synthesized Ag-decorated ZnSe, which showed outstanding stability and a sensitivity limit of 10-12 M. The nanostructure's self-cleaning feature was demonstrated through photocatalytic degradation of R6G and MG molecules under visible light, enabling it to be reused multiple times and showing that it was not limited to a single organic molecule. The bifunctional structure not only offers a unique way of boosting SERS efficiency but is also considerable for photocatalytic behavior.

GREEN SYNTHESIS OF NANOPARTICLES FROM SEAWEEDS – A LITERATURE REVIEW

Marine seaweeds that belong to Chlorophyta, Rhodophyta, and Phaeophyta groups are reported to biosynthesize metal nanoparticles. The morphology and the stability of the nanoparticles obtained from seaweeds for biomedical and environmental applications are equivalent in most aspects to other “green” methodologies. The ability of algae to accumulate metals and reduce metal ions make them a superior contender for the biosynthesis of nanoparticles and hence they are called bio-nano factories as both the live and dead dried biomass are used for the synthesis of metallic nanoparticles. The biosynthesis of nanoparticles using seaweeds can be scaled up to meet industrial requirements. Algae are relatively convenient to handle, less toxic, and less harmful to the environment; synthesis can be carried out at ambient temperature and pressure and in simple aqueous media at a normal pH value. Therefore, this review elaborates seaweeds as a better tool for the fabrication of metal nanoparticles.

Synthesis of Green Engineered Silver Nanoparticles through Urtica dioica: An Inhibition of Microbes and Alleviation of Cellular and Organismal Toxicity in Drosophila melanogaster.

Plant fractions have a diversity of biomolecules that can be used to make complicated reactions for the bioactive fabrication of metal nanoparticles (NPs), in addition to being beneficial as antioxidant medications or dietary supplements. The current study shows that Urtica dioica (UD) and biologically synthesized silver nanoparticles (AgNPs) of UD have antibacterial and antioxidant properties against bacteria (Escherichia coli and Pseudomonas putida) and Drosophila melanogaster (Oregon R+). According to their ability to scavenge free radicals, DPPH, ABTS, TFC, and TPC initially estimated the antioxidant potential of UD and UD AgNPs. The fabricated AgNPs were analyzed (UV-Vis, FTIR, EDS, and SEM) to determine the functional groups (alcohol, carboxylic acids, phenol, proteins, and aldehydes) and to observe the shape (agglomerated crystalline and rod-shaped structure). The disc diffusion method was used to test the antimicrobial properties of synthesized Ag-NPs against E. coli and P. putida. For 24 to 120 h, newly enclosed flies and third instar larvae of Drosophila were treated with UD and UD AgNPs. After exposure, tests for biochemical effects (acetylcholinesterase inhibition and protein estimation assays), cytotoxicity (dye exclusion), and behavioral effects (jumping and climbing assays) were conducted. The results showed that nanoparticles were found to have potent antimicrobial activity against all microbial strains tested at various concentrations. In this regard, ethno-medicinal characteristics exhibit a similar impact in D. melanogaster, showing (p < 0.05) significantly decreased cellular toxicity (trypan blue dye), enhanced biochemical markers (AChE efficacy and proteotoxicity), and improved behavioral patterns in the organism treated with UD AgNPs, especially in comparison to UD extract. The results of this study may help in the utilization of specific plants as reliable sources of natural antioxidants that may have been beneficial in the synthesis of metallic NPs, which aids in the production of nanomedicine and other therapeutic applications.

Strategies adopted for the preparation of sodium alginate–based nanocomposites and their role as catalytic, antibacterial, and antifungal agents

Abstract Alginate extracted from the marine brown algae is a massively utilized biopolymer in multiple fields such as microreactors for the fabrication of metal nanoparticles along with other polymeric and nonpolymeric materials to enhance their mechanical strength. These sodium alginate (Na-Alg)-based fabricated nanocomposites find applications in the field of catalysis and biological treatment as antibacterial/antifungal agent due to the synergistic properties of Na-Alg and fabricated metal nanoparticles (NPs). Na-Alg offers mechanical strength and nanoparticles provide high reactivity due to their small size. Sodium alginate exhibits hydroxyl and carboxylate functional groups that can easily interact with the metal nanoparticles to form composite particles. The research on the preparation of Na-Alg–based nanoparticles and nanoaggregates have been started recently but developed quickly due to their extensive applications in different fields. This review article encircles different methods of preparation of sodium alginate–based metal nanocomposites; analytical techniques reported to monitor the formation of these nanocomposites and used to characterize these nanocomposites as well as applications of these nanocomposites as catalyst, antibacterial, and antifungal agent.

Nanotherapeutic Drug Synthesized by Way of a Microbial Pathway Targeting Staphylococcus aureus

Staphylococcus aureus (S. aureus) is one of the most common human pathogens causing various infectious diseases. Further, its ability to form biofilm and the emergence of antibiotic resistance strains has made it difficult to treat the infection. A nanoparticle-based therapeutic approach is an emerging area to treat S. aureus infection. Among the different methods to synthesize nanoparticles (NPs), the use of microorganisms to fabricate metal nanoparticles with the antibacterial property against S. aureus has been investigated by several studies. The microbial approach is cost-effective, eco-friendly, and devoid of toxic byproducts produced in other methods of nanoparticles formation. The review details the use of bacteria, fungi, yeast, algae, and lichens for producing nanoparticles of various metals, such as silver, gold, zinc, copper, iron, cerium, etc., of varying sizes and shapes and their effective use against S. aureus. The present review focuses on the reports of microbial-fabricated nanoparticles as therapeutic agents for treating S. aureus infection.

Biosynthesis of Gold Nanoisotrops Using Carallia brachiata Leaf Extract and Their Catalytic Application in the Reduction of 4-Nitrophenol.

The past decade has observed a significant surge in efforts to discover biological systems for the fabrication of metal nanoparticles. Among these methods, plant-mediated synthesis has garnered sizeable attention due to its rapid, cost-effective, environmentally benign single-step procedure. This study explores a step-wise, room-temperature protocol for the synthesis of gold nanoparticles (AuNPs) using Carallia brachiata, a mangrove species from the west coast of Peninsular Malaysia. The effects of various reaction parameters, such as incubation time, metal ion concentration, amount of extract and pH, on the formation of stable colloids were monitored using UV-visible (UV-Vis) absorption spectrophotometry. Our findings revealed that the physicochemical properties of the AuNPs were significantly dependent on the pH. Changing the pH of the plant extract from acidic to basic appears to have resulted in a blue-shift in the main characteristic feature of the surface plasmon resonance (SPR) band, from 535 to 511 nm. The high-resolution-transmission electron microscopy (HR-TEM) and field emission scanning electron microscopy (FESEM) images revealed the morphologies of the AuNPs synthesized at the inherent pH, varying from isodiametric spheres to exotic polygons and prisms, with sizes ranging from 10 to 120 nm. Contrarily, an optimum pH of 10 generated primarily spherical-shaped AuNPs with narrower size distribution (8–13 nm). The X-ray diffraction (XRD) analysis verified the formation of AuNPs as the diffraction patterns matched well with the standard value of a face-centered cubic (FCC) Au lattice structure. The Fourier-transform infrared (FTIR) spectra suggested that different functional groups are involved in the biosynthetic process, while the phytochemical test revealed a clear role of the phenolic compounds. The reduction of 4-nitrophenol (4-NP) was selected as the model reaction for evaluating the catalytic performance of the green-synthesized AuNPs. The catalytic activity of the small, isotropic AuNPs prepared using basic aqueous extract was more effective than the nanoanisotrops, with more than 90% of 4-NP conversion achieved in under an hour with just 3 mg of the nanocatalyst.

Green Synthesis of Silver Nanoparticles from Root Extracts of Rubus ellipticus Sm. and Comparison of Antioxidant and Antibacterial Activity

The fabrication of metal nanoparticles through green synthetic pathways using plant extracts has increased attention due to low cost, benevolent methods, fewer hazardous byproducts, and applications. Silver nanoparticles (AgNPs) were synthesized by reacting to aqueous root extracts of Rubus ellipticus Sm. (RERE) with AgNO3 solution (1 mM) at an ambient condition. The visual change of color from light yellow to reddish brown and the absorption peak at 416‐420 nm in the UV‐visible spectra indicated the formation of AgNPs in the solution. The shifting of the positions in the FTIR spectra indicated the potential role of the functional groups as capping and stabilizing agents. The powder XRD diffractogram exposed the crystalline nature of the nanoparticles. The surface morphology and the elemental composition of the AgNPs were established by the FESEM and EDX analysis. The TEM images revealed the spherical and monodispersed nanoparticles of size ranging from 13.85 to 34.30 nm with an average of 25.20 ± 7.01 nm (n = 10). The biogenic AgNPs showed a better 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical scavenging activity with lower IC50 (13.83 ± 0.33 μg/mL) as compared to that of the RERE with IC50 (15.86 ± 4.14 μg/mL). The synthesized AgNPs showed higher zones of inhibition (ZOI) on the agar well diffusion method against Enterococcus faecalis (ATCC 29212), Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), and Klebsiella pneumoniae (ATCC 700603). The result of this study highlights the potential benefits of R. ellipticus root extract‐based AgNPs for biomedical practices.

Controlling size and distribution of Ag nanoparticles in near surface of SiO2 glass by low-energy ion implantation

Ag nanoparticles were embedded in the near surface of SiO2 substrate and fabricated by low-energy ion implantation method in this study. The optical and structural properties of Ag implanted samples were investigated using optical spectroscopy, transmission electron microscope (TEM) and atomic force microscopy (AFM). The grain size and distribution of nanoparticles embedded in the substrate were characterized by TEM and AFM characterization. Results showed that the grain size and depth of distribution of nanoparticles were controlled by changing the ion implantation energy and dose. Furthermore, the Ag nanoparticles embedded near surface of substrate prepared by this low-energy ion implantation method had strong local surface plasmon resonance (LSPR) characteristics. Our work demonstrates a practical means for fabrication of metal nanoparticles with controllable size and distribution using ion implantation technology, which is helpful to the application of local plasmon resonance effect of metal nanoparticles.

Plant Extract Mediated Synthesis of Metal Nanoparticles, their Characterization and Applications: A Green Approach

: Nowadays, nanoparticles are gaining enormous importance in a wide variety of disciplines due to their unambiguous physical and chemical properties. There are lots of physical and chemical approaches available for the synthesis of metal nanoparticles. But there are certain disadvantages associated with these methods, such as adsorption of hazardous toxins on the surface of the material, high capital investment, high manufacturing energy demand, etc., which make their effective implementation almost impossible. An alternative method of synthesizing nanoparticles to avoid the aforementioned disadvantages is to use different parts of the plant under aqueous conditions. Plant-mediated approach for the synthesis of nanoparticles is becoming increasingly popular due to its faster reaction rate, easily affordable, eco-friendly nature and rich diversity of plants. Chemical compositions of plant extracts are examined using the liquid chromatography-mass spectrometry technique. Noble metals such as Silver, Gold, Iron, Copper, Platinum, Zinc, Palladium, and their oxides are used for the fabrication of metal nanoparticles, due to their enormous potential applications. In a single-step green synthesis process, the phytochemical constituents which are present in plant extract reduce metal salts into metal nanoparticles. This article gives an overview of plant-mediated synthesized metal and metal oxide nanoparticles and their characterization by using different techniques, together with their properties and applications in numerous fields.

Complex Metal Nanostructures with Programmable Shapes from Simple DNA Building Blocks.

Advances in DNA nanotechnology allow the design and fabrication of highly complex DNA structures, uisng specific programmable interactions between smaller nucleic acid building blocks. To convey this concept to the fabrication of metallic nanoparticles, an assembly platform is developed based on a few basic DNA structures that can serve as molds. Programming specific interactions between these elements allows the assembly of mold superstructures with a range of different geometries. Subsequent seeded growth of gold within the mold cavities enables the synthesis of complex metal structures including tightly DNA-caged particles, rolling-pin- and dumbbell-shaped particles, as well as T-shaped and loop particles with high continuity. The method further supports the formation of higher-order assemblies of the obtained metal geometries. Based on electrical and optical characterizations, it is expected that the developed platform is a valuable tool for a self-assembly-based fabrication of nanoelectronic and nanooptic devices.

A Three-Dimensional Printable Liquid Metal-Like Ag Nanoparticle Ink for Making a Super-Stretchable and Highly Cyclic Durable Strain Sensor.

Fabrication of metal nanoparticle (NP)-based strain sensors with both a broad working range and linearity range is still a significant challenge. Typically, homogeneous conductive percolation networks are indispensable for linear sensing performance, whereas inhomogeneous microstructures may inevitably arise under large strain due to the formation of defects in rigid NPs. In this study, a sandwich-structured strain sensor with an extraordinarily large stretchability (800%) yet self-healing property is fabricated by three-dimensional printing using a liquid metal-like Ag NP ink. The strain sensor shows an initial conductivity of 248 S cm-1, a good linearity in two strain ranges, and a long-term stability after undergoing 5000 cycles under a strain level of 100%. Such highly comprehensive sensing performance is attributed to the unique structure of the Ag NP ink, in which Ag NPs coalesce together after room-temperature sintering triggered by chlorides, and then, the sintered Ag aggregates tend to form continuous conductive networks through hydrogen bonds between polyacrylic acid and carboxymethylcellulose. Further, the free flow of Ag aggregates is the root cause that leads to the change of relative resistance as demonstrated by finite element simulation. This Ag NP-based strain sensor shows high potential for application in monitoring human knuckle motion.

One-step fabrication of metal nanoparticles on polymer film by femtosecond LIPAA method for SERS detection

Flexible transparent SERS substrates have aroused great interest as a rapid and in situ detection method for trace chemicals. We demonstrate a one-step and environmentally friendly method to fabricate flexible fluorinated ethylene propylene (FEP) surface plasmon resonance film by femtosecond laser induced plasma assisted ablation (LIPAA) for in situ SERS detection. By tuning laser fluence, the distributions and sizes of silver and gold nanoparticles generated by femtosecond LIPAA are studied. Using a Rhodamine 6G (R6G) Raman probe with a 532 nm laser excitation, the proposed Ag NPs/FEP and Au NPs/FEP substrates show enhancement factors of 5.6 × 107 and 2.4 × 106, respectively, as compared to a bare FEP film without the metallic nanoparticles. The Raman signals show good uniformity and a linear relationship with the concentration of R6G solution. In addition, the detection limit of thiram on an apple for in situ measurement is 0.1 mg/Kg, corresponding to 7.96 ng/cm2. The proposed SERS detection approach has great potential to pave a new way in food safety applications, such as detecting pesticides in harvested fruits.

Green approach in gold, silver and selenium nanoparticles using coffee bean extract

Abstract Green fabrication of metal nanoparticles (NPs), using natural reducing and stabilizing agents existed in plants and their derivatives, due to their unique properties, has gained more attention. The present study focuses on the synthesis of gold (Au), silver (Ag) and selenium (Se) NPs using coffee bean extract under hydrothermal conditions (1.5 atm and 121°C, for 15 min). Coffee bean extract obtained in 2 h processing using Clevenger apparatus and Fourier transform-infrared (FT-IR) spectroscopy indicated five highlighted peaks, namely, hydroxyl, amide, aromatic, alkane and ring groups. Dynamic light scattering analysis revealed that among three different NPs formed, fabricated Ag NPs had small particle size (153 nm) and high zeta potential value (16.8 mV). However, synthesized Au NPs had minimum polydispersity index (0.312). Results also indicated that fabricated Au, Se and Ag NPs had low antioxidant activity with values of 9.1, 8.9 and 8.7%, respectively. Morphological and antibacterial activity assessments, demonstrated that synthesized Ag, Au and Se NPs had spherical shape and high bactericidal activity against E. coli and S. aurous. Obtained results indicated that the synthesized NPs, can be utilized in various areas.