Formation Of Ag Nanoparticles Research Articles

UV-Catalyzed TiO2-Based Optofluidic SERS Chip for Three Online Strategies: Fabrication, Detection, and Self-Cleaning.

We developed an optofluidic surface-enhanced Raman scattering chip capable of online fabrication, online molecular detection, and online self-cleaning. In this chip, we harnessed UV light to successfully reduce an AgNO3 solution, resulting in the formation of Ag nanoparticles on carbon fiber cloth coated with titanium dioxide (TiO2). This innovative approach enabled the online fabrication of AgNPs@TiO2-CFC SERS structures. By introducing target molecules into our optofluidic SERS chip, we achieved online molecular Raman detection. Furthermore, by leveraging the UV light-induced self-cleaning properties of TiO2, we achieved continuous online self-cleaning of the molecules. To verify the feasibility and stability of our method, we conducted multiple experiments for online detection and self-cleaning. Experimental results demonstrated impressively low detection limits of 10-8 mol/L for crystal violet and 10-9 mol/L for rhodamine 6G, with an enhancement factor as high as 1.4 × 106. Additionally, we successfully applied our method to polycyclic aromatic hydrocarbons like pyrene.

One‐step synthesis of a spongy flexible substrate for surface enhanced Raman spectroscopy comprising a silver nanoparticles‐loaded poly(amidoamine) dendrimer crosslinked with glutaraldehyde

AbstractA composite comprising a silver nanoparticles‐loaded poly(amidoamine) (PAMAM) dendrimer crosslinked with glutaraldehyde (PAMAM/AgNPs) is synthesized using a one‐step method under vortex at room temperature. The structure of glutaraldehyde‐crosslinked PAMAM dendrimer is characterized using FTIR and high‐resolution magic angle spinning–carbon 13 nuclear magnetic resonance (HRMAS 13C NMR) spectroscopy. The crosslinking structure ensures the uniformity and stability of the Ag nanoparticles, and the flexibility of the PAMAM/AgNPs composite. X‐ray diffraction (XRD) analysis and energy dispersive spectroscopy (EDS) confirm the formation of Ag nanoparticles in the PAMAM/AgNPs composite. Scanning electron microscopy (SEM) and three‐dimensional (3D) micro‐Raman images reveal the coarsely porous 3D micro‐structure of the PAMAM/AgNPs composite. This unique micro‐3D architecture provides the PAMAM/AgNPs composite with spongy flexibility and a swab‐like nature, which is advantageous for the rapid and effective absorption of liquid samples on the surfaces of objects. Surface enhanced Raman spectroscopy (SERS) indicates that the detection limits of both rhodamine 6G (R6G) and thiram are 1.0 × 10−5 mol L−1, and the SERS enhancement factor of R6G is determined to be 1.35 × 104. The spongy flexible PAMAM/AgNPs SERS substrate therefore has potential for use in Raman active compound detection.

Insights on the effect of process conditions on the optical properties of silver ion exchanged soda-lime silicate glass

The effects of ion exchange time and temperature on the optical properties and plasmonic response of silver ion exchanged soda-lime silicate glass were investigated using scanning electron microscopy (SEM) in energy dispersive spectrometry (EDS) configuration, m-lines spectroscopy, photoluminescence (PL) spectroscopy, and UV–visible absorption spectroscopy. SEM analyses in EDS mode provided profiles of silver oxide molar concentration. These profiles were directly correlated to the silver diffusion coefficient using an adjustment procedure. The effective indices of ion exchanged glasses measured by the standard prism coupling technique (m-lines) allowed access to refractive index distributions in ion exchange regions. These ion-exchanged glasses underwent evaluation to determine their potential suitability for use in multimode planar systems. The PL results acquired after ion exchange demonstrated that the creation of Ag0 atoms from Ag+ ions was responsible for the decline and quenching of PL intensity at ion exchange times and temperatures increase. Silver nanoparticles were generated in the samples subjected to ion exchange at 480 °C without the need for post-exchange treatments. The emergence of the surface plasmon resonance band around 427 nm in the optical absorption spectra confirmed the formation of Ag nanoparticles in annealed glasses. Estimates of the UV–visible absorption spectra indicated an average size of silver nanoparticles ranging from 1.8 to 2.4 nm.

Green synthesis of silver nanoparticles decorated on graphene oxide for crystal violet dye removal

In this study, we demonstrate a facile and environmentally benign method for the synthesis of Ag nanoparticles using a green reducing agent and their subsequent deposition onto GO sheets. The synthesized GO@Ag nanocomposite was characterized using various analytical techniques such as FTIR, XRD, FESEM, EDX and BET. The results confirmed the successful formation of cubic Ag nanoparticles with diameter 30–40 nm on the GO surface. The theoretical surface area of GO@Ag was found to be 89 m2/g. The adsorption efficiency of GO@Ag nanocomposite toward CV dye was evaluated through batch adsorption experiments. The above experimental results revealed that CV adsorption on to the GO@Ag surface was pH dependent and maximum adsorption capacity was found to be 48.78 mg/g at pH = 8. The adsorption process followed pseudo-second-order kinetics and Langmuir isotherm models, indicating monolayer adsorption with chemisorption as the rate-limiting step. Furthermore, the recyclability and stability of the nanocomposite were assessed through multiple adsorption-desorption cycles, demonstrating its potential for practical applications in wastewater treatment for the removal of cationic dyes. The mechanism of CV adsorption on to the GO@Ag surface mainly involves electrostatic attraction and π-π interaction.

Phyto-mediated synthesis of Ag, ZnO, and Ag/ZnO nanoparticles from leave extract of Solanum macrocarpon: Evaluation of their antioxidant and anticancer activities

Silver, zinc oxide, and silver/zinc oxide nanocomposites were prepared from the facile green process using Solanum macrocarpon leave extract. Ag and ZnO nanoparticles (NPs) were composited with the aim of enhancing the synergy for improved antioxidant and anticancer activities. In the synthesis process, the formation of Ag NPs was initially observed by a colour change and was confirmed by the appearance of surface plasmon resonance (SPR) bands. Based on the crystallographic analysis of the diffraction patterns, the phyto-capped silver NPs possessed a crystalline character, featuring a lattice structure of face-centered cubic (FCC) and an estimated crystallite size of around 7.2 nm. The formation of a hexagonal crystal structure of spherical morphology was confirmed for the ZnO, while the Ag/ZnO composite showed additional planes due to the silver nanoparticles in the cubic phase. The scavenging activities of 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radicals and their anticancer potency on normal HEK and cancerous HELA cells were examined in comparison to standard drugs. They demonstrated remarkable IC50 values that were better than the control drugs. This study provides helpful insight into the synergy between Ag and ZnO nanoparticles for the possible development of new anticancer and antioxidant agents.

Thiazole-Based Silver Ion Sensor for Sequential Colorimetric Visualization of Epinephrine in the Brain Tissues of an Alzheimer's Disease Model of Mouse.

A thiazole-based probe, N'-((2-aminothiazol-5-yl)methylene)benzohydrazide (TBH), has been efficiently synthesized and characterized for the selective and sensitive detection of the neurotransmitter epinephrine (EP). The sensing strategy is based on the use of TBH for sequential colorimetric sensing of Ag+ and EP via in situ formation of Ag nanoparticles (Ag NPs) from the TBH-Ag+ complex. The generated Ag NPs lead to a bathochromic shift in absorption maximum and a change in color of the solution from light brown to reddish brown. TBH-Ag+ shows remarkable selectivity toward EP versus other drugs, common cations, anions, and some biomolecules. Moreover, TBH-Ag+ has a low detection limit for EP at 1.2 nM. The coordination of TBH-Ag+ has been proposed based on Job's plot, Fourier transform infrared spectroscopy (FT-IR), high-resolution mass spectrometry (HRMS), 1H NMR titration, X-ray photoelectron spectroscopy (XPS), energy-dispersive X-ray analysis (EDAX), and density functional theory (DFT) studies. The composition and morphology of the generated Ag NPs have been analyzed by XPS, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). The proposed sensing mechanism for EP has been supported by XPS of Ag after the reaction. Further, the sensitivity of TBH-Ag+ toward EP in brain tissues of an Alzheimer's disease model of mouse has been evaluated. A thorough comparison was done for evaluation of the proposed method.

Hybrid Materials Obtained by Immobilization of Biosynthesized Ag Nanoparticles with Antioxidant and Antimicrobial Activity.

Ag nanoparticles (AgNPs) were biosynthesized using sage (Salvia officinalis L.) extract. The obtained nanoparticles were supported on SBA-15 mesoporous silica (S), before and after immobilization of 10% TiO2 (Degussa-P25, STp; commercial rutile, STr; and silica synthesized from Ti butoxide, STb). The formation of AgNPs was confirmed by X-ray diffraction. The plasmon resonance effect, evidenced by UV-Vis spectra, was preserved after immobilization only for the sample supported on STb. The immobilization and dispersion properties of AgNPs on supports were evidenced by TEM microscopy, energy-dispersive X-rays, dynamic light scattering, photoluminescence and FT-IR spectroscopy. The antioxidant activity of the supported samples significantly exceeded that of the sage extract or AgNPs. Antimicrobial tests were carried out, in conditions of darkness and white light, on Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Candida albicans. Higher antimicrobial activity was evident for SAg and STbAg samples. White light increased antibacterial activity in the case of Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa). In the first case, antibacterial activity increased for both supported and unsupported AgNPs, while in the second one, the activity increased only for SAg and STbAg samples. The proposed antibacterial mechanism shows the effect of AgNPs and Ag+ ions on bacteria in dark and light conditions.

Green Synthesis of Ag/Mg(OH)2 Nanocomposite from Potato Peel Extract (Solanum tuberosum) and Its Antioxidant Activity

Potato peel extract (PPE) is a rich source of polyphenols which could be used as reducing agents for the green synthesis of nanocomposites. The project aims to synthesize Ag/Mg(OH)2 nanocomposites (NCs) by using PPE and investigate its antioxidant activity. The phytochemicals in peel extract act as reducing, stabilizing, and capping agents in the reduction of precursor salts. SEM-EDX analyses of the bio-synthesized Ag/Mg(OH)2 NCs show the formation of Ag nanoparticles (NPs) on the surface of Mg(OH)2 carriers with various sizes in the nanoscale, while XRD patterns suggest the existence of Mg(OH)2 hexagonal crystalline structure. The antioxidant activity of Ag/Mg(OH)2 NCs was assessed through the DPPH free radical scavenging assay with IC50 values between 1.3 and 1.4 mg/mL. Compared to various plant-based Ag NPs, such values are remarkably closer to the IC50 of the standard ascorbic acid (0.6 mg/mL), promoting PPE-based Ag/Mg(OH)2 as an effective and ecofriendly antioxidant.

Water‐soluble astaxanthin and silver enriched poly(vinyl alcohol)/silk fibroin crosslinking electrospun nanofiber for wound dressing

AbstractThe aim of this work is to fabricate a novel electrospun poly(vinyl alcohol) (PVA)/silk fibroin (SF) nanofibrous membrane containing astaxanthin (ASTA) and silver (Ag) nanoparticles as potential wound dressing. Since ASTA is typically liposoluble, the bioavailability could be greatly enhanced by improving its hydrophilicity. The antioxidant performance of eletrospun membrane is verified by ABTS radical scavenging assays. The beadless fibers could be fabricated at 16 kV when PVA (12, wt%) is blended with SF (6, wt%). In addition, the membrane is carefully chemically crosslinked by comparing the efforts (i.e., mechanical strength and water resistance) of glutaraldehyde dipping and vapor treatment. The morphology of the electrospun membrane is observed by scanning electron microscopy and optical microscope. The formation of Ag nanoparticles, which provides the membranes antibacterial properties, is also confirmed by energy dispersive spectroscopy and inhibition zone test. Meanwhile, the PVA/SF/ASTA/Ag compound membrane is characterized by Fourier transform infrared spectroscopy, x‐ray diffraction, thermo gravimetric analysis, differential thermal analysis, and water contact angle. The releasing of ASTA is also measured, and kinetic data are adjusted by Higuchi models. Finally, the biocompatibility is confirmed by in vitro cell staining experiments and in vivo rat models.

Smart 3D Ag-decorated TiO2 Nanostructure: An advanced synergistic SERS substrate for trace detection of analytes with diverse natures

Designing surface-enhanced Raman scattering (SERS) substrates that combine multiple advanced features in synergy is highly desirable for the SERS technique, however, it has been a long-standing challenge due to inherent trade-offs in feature selection. For instance, while nanoplasmonic surface functionalization bolsters attraction to target analytes, it simultaneously introduces barriers to direct contact. Similarly, the intrinsic hydrophilic or hydrophobic nature of substrates often limits their sensing effectiveness across a wide range of analyte types. Here, we demonstrate a smart 3D Ag-decorated TiO2 nanostructure, an advanced synergistic SERS substrate, created by controlling the formation of Ag nanoparticles on functionalized TiO2 nanomaterials, which integrates four unique features: uniform hotspot distribution, efficient analyte trapping, accessible plasmonic surfaces, and dual-phase detection. This design brings unachieved sensor efficiency across a diverse array of analytes with varying sizes and hydrophobicity. Moreover, our design exhibits a novel dual-phase detection capability within mixtures of hydrophilic and hydrophobic analytes. As a proof-of-concept, our results highlight the potential of designing SERS substrates with multiple advanced features that work synergistically, enabling trace detection of a broader range of analyte types in various environments. More broadly, we anticipate that this work paves the way for the development of other nanomaterials that are capable of attracting diverse molecules while retaining key features such as accessible plasmonic surfaces and wide-area ordered hotspot distribution. Such nanomaterials could be powerful for advanced applications in hotspot engineering, surface analysis, catalysis, and plasmon-mediated reactions.

Structure and optical characterization of chitosan-chitin/Ag nanocomposite thin films

Chitin and its derivatives are common natural polymers that are widely used in various technological fields. In recent years, considerable attention has been paid to the preparation of polymer nanocomposites based on metal nanoparticles (NPs). Chitin/chitosan-based composites due to high antibacterial activity are suitable for application in related food storage, textile industries. This paper presents an effective and simple method of obtaining chitosan-chitin copolymer/Ag nanocomposites with an extremely high content of metal nanoparticles. The structure and morphology of the synthesized nanocomposites were investigated using X-ray diffractometry, Fourier-transform infrared spectroscopy, electron microscopy, and their optical properties were studied using UV-VIS spectroscopy as well as spectral ellipsometry. It was ascertained that the resulting nanocomposite films are characterized by a uniform distribution of spherical silver nanoparticles, the sizes of which increase (from 55 up to 143 nm) with increasing the Ag+-ions concentration in the reaction mixtures. The optical absorption spectra of nanocomposites are characterized by the presence of an absorption maximum within the range 458…525 nm, which confirms the formation of Ag NPs. A monotonous increase in the values of the energies of optical transitions was observed in the process of increasing the average size of NPs

Gelation of acrylic acid with Ag+ and conversion to Ag nanoparticle as potential system for biomedical applications

Silver (Ag) has been used to cross-link poly (acrylic acid) (PAAc) to obtain antibacterial nanocomposite hydrogel for controlled drug delivery systems. Ag+/PAAc composite hydrogel was prepared by free radical aqueous polymerization of acrylic acid (AAc) using potassium persulfate (KPS) as the initiator in the presence of silver nitrate (AgNO3). Sodium borohydride (NaBH4) was used to reduce the Ag ions present within the hydrogel matrix to generate Ag nanoparticles (Ag NPs). Transmission electron microscopy (TEM) characterization of the sample indicated the formation of Ag nanoparticles that distributed uniformly in the PAAc networks. UV–visible spectrophotometry showed an absorption peak at 425 nm that attribute to the well-known surface Plasmon resonance of the Ag bound in NPs. X-ray diffraction (XRD) pattern showed the appearance of some peaks corresponding to the face-centered cubic (f.c.c.) Ag phase. Energy dispersive spectroscopy (EDS) studies revealed that Ag NPs are successfully formed inside the Ag+/PAAc composite hydrogel. The gelation and crosslinking of PAAc chains with Ag+ by strong interactions between Ag cations and polyanions, deprotonated carboxylic groups of PAAc were identified from the Fourier transform infrared (FTIR) spectrogram. Field emission scanning electron microscopy (FESEM) exhibited an interconnected porous structure with an average pore size of about 10 μ for composite hydrogel that can absorb 440 g water/g dried sample. Dried samples were also loaded with amoxicillin and antibiotic release was studied. The antimicrobial activity of the Ag+ and Ag-NPs hydrogels was tested against Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa and Escherichia coli.

Experimental and Theoretical Studies on Ag Nanoparticles with Enhanced Plasmonic Response, Formed Within Al2O3 Thin Films Deposited by Magnetron Sputtering

AbstractReactive magnetron sputtering was employed to prepare nanocomposite thin films of Ag/Al2O3, on a glass substrate. The films are characterized by the formation of Ag nanoparticles embedded in the Al2O3 matrix, after thermal treatment at 600 °C, which are responsible for the appearance of an outstanding pronounced and narrow localized surface plasmon resonance (LSPR) band. Electron microscopy analysis also revealed the presence of larger Ag fractal aggregates at the film’s surface, responsible for a broad band absorption. Noteworthily, the LSPR band maximum remains at the same position (about 412 nm) for Ag concentrations ranging from 23 to 34 at.%, despite some discernible alterations in both LSPR band intensity and width. An optimized thin film is characterized by full transparency in non-resonant wavelengths due to suppression of Ag aggregates at the film’s surface, while maintaining the LSPR behavior. To better explain the plasmonic behavior of the Ag/Al2O3 films, discrete dipole approximation was used to determine the extinction, scattering, and absorption efficiencies of Ag spheres surrounded by an Al2O3 cap layer. This allowed to ascertain some nanostructural features of the films, pointing to the formation of Ag nanoparticles with average sizes in the order of 40 nm.

The impact of heat treatment on the luminescence properties of Dy/Ag co-doped sodium alumina borate glasses

The sodium alumina borate glasses were synthesized by conventional melt-quenching method and heat treated with different durations to ensure the formation and growth of Ag nanoparticles. Transmission electron microscope measurements revealed that the average nanoparticle size increases with the heat treatment duration. The bonding nature between Dy3+ ions and surrounding ligands was getting more covalent with HT. Judd-Ofelt intensity parameters proved the asymmetric nature around Dy3+. The most intense emission and excitation bands of Dy3+ ions were observed for 6 h heat-treated glass (HT-6h). Intense blue (483 nm) and yellow (572 nm) emissions were obtained in which the yellow one has the highest radiative parameters approving the suitability of glasses for yellow laser applications. Based on colorimetric results emission closest to white light can be generated by HT-6h under 426 nm excitation. The decay time of 4F9/2 → 6H13/2 transition increases with heat treatment attributed to the combined effect of the enhanced local electric field induced by the Ag nanoparticles and energy transfer from Ag species to Dy3+ ions. The findings show that Dy3+/Ag+ co-doped sodium alumina borate glasses are potential materials for photonic applications.

Ambient formation of high pressure Ag2Si2O5 and non-stoichiometric Ag0.3Al0.7 alloy under confinement

We report results of Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive Analysis of X-rays (EDAX), X-ray Photoelectron Spectroscopy (XPS), X-ray Reflectivity (XRR), and X-ray Diffraction (XRD) and residual stress measurement studies of Ag-silica composite films on Al(001) co-deposited from precursors and spin-coated at different frequencies under ambient conditions. FESEM and EDAX show Ag nanoparticle formation, and XRD, XPS, and XRR show Ag0.3Al0.7 alloy and Ag-rich silicate Ag2Si2O5 formation in all samples. The alloy is non-stoichiometric and non-equilibrium, while the silicate forms at high oxygen pressure. XRR shows the presence of three layers, nanoparticles on top, silicate in the middle, and alloy at the bottom, on an Ag-doped Al substrate. Film thickness decreases exponentially with frequency. Individual layers increase in crystal domain size with a frequency of 3000 rpm when the silicate layer thins below unit cell thickness and the growth has a two-dimensional preference. Our results suggest total confinement by film thinning and local confinement from the Ag nanolayer. Residual stress measurements on the films deposited at 500 and 5000 rpms show a gradual increase in the tensile stress. The increase in spinning frequency reveals the formation of high pressure ambience.

Electrical properties of PbO–Bi2O3–Ga2O3 glasses with addition of Ag2O and Sb2O3

Formation of Ag nanoparticles in the PbO–Bi2O3–Ga2O3 heavy metal oxide glasses modified by addition of Ag2O and Sb2O3 was monitored using electrical and optical measurements. Electrical measurements are suitable for this purpose as they are very sensitive to any changes in the arrangement of the material structure. The formed spherical silver nanoparticles were studied by a high-resolution transmission electron microscopy (HRTEM), their nature was confirmed by selected area electron diffraction analysis (SAED) and x-ray photoelectron spectroscopy (XPS). We demonstrated and documented that the samples containing Ag/Sb change during additional heating (in the investigated temperature range of 240–290 °C) – the electrical conductivity changes and also the relaxation time as established by electrical modulus measurements changes. The behaviour of the base glass without Ag/Sb addition remains practically unaffected by the same additional heating. TEM confirmed an increased number of spherical nanoparticles as a consequence of heat treatment. The indexes of the SAED pattern match the fcc-Ag crystalline phase, HRTEM identified the periodical arrangement in these particles to correspond to d-spacing of (111) planes in Ag and the elemental state of the present Ag in the heat-treated sample was confirmed also by XPS.

Catalytic oxidation of ammonia: A pre-occupied-anchoring-site strategy for enlarging Ag nanoparticles at low Ag loading and achieving enhanced activity and selectivity on Ag-CuOx/Al2O3 catalyst

The Ag nanoparticles (AgNPs) in Ag/Al2O3 catalysts play a crucial role in the selective catalytic oxidation of NH3 (NH3-SCO). To enhance NH3-SCO activity, Cu, which has stronger anchoring ability than Ag, is introduced onto Al2O3, reducing available anchoring sites for Ag. As Ag cannot displace anchored Cu species, Ag species agglomerate into larger AgNPs even with low Ag loading. Consequently, these enlarged AgNPs become more active centers for NH3-SCO. The optimal Ag:Cu molar ratio is confirmed as 2:3. This 'pre-occupied-anchoring-site’ strategy decreases Ag loading to 1/5 of the original, reducing catalyst costs while maintaining activity. In situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) studies reveal that NH3-SCO on 2Ag1.8Cu/Al (weight ratio) catalyst follows the hydrazine mechanism below 200 °C, coexisting with the imide mechanism from 200–250 °C, and solely the imide mechanism beyond 250 °C. This strategy is applicable to various transition metals, including Mn, Co, Ni, and Fe, promoting cost-effective AgNPs formation.

Green synthesis and structural and cytotoxic properties of a new silver(I) complex: Solid-state, single-source precursor of Ag and Ag2O NPs

A new silver complex, [Ag(2-pymc)(NO3)] (Ag-1) [2-pymc = methyl-2-(pyridine-2yl-methylene) hydrazinecarboxylate], was prepared and subjected to elemental analysis including Fourier transform infrared (FT-IR) and ultraviolet–visible (UV–vis) spectroscopic methods. Single-crystal X-ray diffraction (SC-XRD) study demonstrated [Ag(2-pymc)(NO3)] monomers in the crystal structure. The silver ion is triple coordinated by an N, N-chelating 2-pymc and one oxygen atom of a monodendate nitrate anion. Interestingly, Ag-1 acted as a single-source, solid-state molecular precursor (SSMP) for synthesizing both Ag and Ag2O nanoparticles (NPs) at different reaction conditions. The crystallinity and purity of the as-synthesized Ag and Ag2O NPs were investigated by powder XRD, whereas the size and surface morphology were determined by TEM analysis. The results showed that the formed Ag NPs were well dispersed and spherically shaped with an average diameter of 30–32 nm. The Ag2O NPs were not homogeneous but showed irregular shapes with an average diameter of 40–42 nm. Ag-1 showed antibacterial activity against selected Gram-positive (Bacillus megaterium) and Gram-negative (Pseudomonas Stutzeri) bacteria. The cytotoxicity of Ag-1 against MCF-7 cancer cells was also tested.

Finely Dispersed Fe3O4 and Ag Nanoparticles Adhered by Starch Nano‐layers: an Efficient Catalyst for the Synthesis of Pyrano[2,3‐d]Pyrimidines

AbstractHot‐water‐soluble starch (HWSS) was employed as binder for fabrication of a composite from magnetite and Ag nanoparticles (NPs). Electron microscopy images showed a good dispersion of magnetite NPs in the matrix of HWSS. This observation indicates that HWSS tends to coat the maximum surface of magnetite by encapsulation of individual magnetite NPs, leading to disassembly of their aggregates. The HWSS‐coated magnetite NPs were employed as nano‐support for immobilization of fine Ag NPs generated in situ via reduction of Ag+ cations by glucose. Monitoring of the formation and growth of Ag NPs by UV–Vis spectroscopy made it possible to set up an optimal condition for fabrication of the nano‐composite and to verify the supremacy of HWSS‐coated magnetite NPs over bare magnetite NPs as support in this new protocol. Valuable insights into the texture of the nano‐composite were obtained by VSM, FT‐IR and XRD studies. The bio‐derived nano‐composite displayed an interesting magnetic property and an efficient catalytic activity in the three‐component synthesis of pyrano[2,3‐d]pyrimidines. It is a robust heterogeneous catalyst and can be simply retrieved from reaction mixtures by magnetic separation method.

Enhanced reddish-orange luminescence from Sm3+/Ag co-doped barium zinc borophosphate glasses: Structural and Judd-Ofelt analysis

We report the synthesis and optical response of Sm3+/Ag nanoparticles (NPs) co-doped glasses through melt quenching method. TEM analysis confirmed Ag NP formation, and the diverse functional groups were confirmed through FTIR studies. The Judd-Ofelt (JO) parameters are calculated using JO theory from absorption spectra. The PL spectra were recorded under 402 nm excitation and they show four PL bands in the visible range. The PL spectra are utilized to obtain radiative parameters to claim their utility in visible laser applications. The dominant emission color was obtained by using the CIE color chromaticity diagram. The excited state lifetime values were estimated through decay curve fitting method. All the obtained results are discussed in detail based on Ag NP concentrations.