Synthesis Of Silver Nanoclusters Research Articles

Synthesis of silver nanoclusters using a double-stranded DNA template and its application for captopril detection

The purpose of this study was to explore the feasibility and mechanism of synthesizing silver nanoclusters (AgNCs) using a double-stranded DNA (dsDNA) template and to use the AgNCs as probes for captopril detection. The results showed that the binding of silver ions towards DNA bases deduced the destruction of the initial dsDNA structure, and AgNCs with decent quantum yield (43.54%) were obtained. The detection using these AgNCs probes showed good performance for captopril, with a linear range of 0.1–0.8 μg·mL−1 and a detection limit of 0.045 μg·mL−1. Recovery results in real samples of Apocynum venetum leaf tea and Ginkgo biloba leaf tablet demonstrated its good applicability. This work not only extended the understanding of DNA-AgNCs but also provided a fast and cost-effective tool for captopril detection.

Synthesis of Silver Nanoclusters and Nanoparticles in the Medium of Hyperbranched Polyester Polyamine, and the Morphology and Aggregation Properties of the Metal–Polymer Nanocomposite

A procedure was developed for the single-step synthesis of a metal–polymer nanocomposite based on silver nanoparticles and second-pseudogeneration superbranched polyester functionalized along the periphery with 3-[(2-aminoethyl)amino]propionate. Under the conditions of the synthesis in the medium of H2O or DMSO, hyperbranched polyester decorated with ethylenediamine moieties can act as both a reductant of the nanoscale silver state and a stabilizer of it. The synthesized composite nanomaterial is formed by aggregates of hyperbranched polyester polyamine doped with Ag(0) nanoclusters and nanoparticles of spheroidal symmetry with a face-centered cubic crystal lattice. The hydrodynamic diameter of aggregates and the diameter of particles increase with increasing molar ratioand are 34–90 and 7–14 nm, respectively.

Synthesis of Silver Nanoclusters and Nanoparticles in the Medium of Hyperbranched Polyester Polyamine, and the Morphology and Aggregation Properties of the Metal–Polymer Nanocomposite

Synthesis of Silver Nanoclusters and Nanoparticles in the Medium of Hyperbranched Polyester Polyamine, and the Morphology and Aggregation Properties of the Metal–Polymer Nanocomposite

Synthesis of Silver Nanoclusters from <i>Melia azedarach</i> and their Usage for Catalytic Degradation of Variable Organic Dyes

Silver nanoclusters (AgNCs) were synthesized from leaf extract of Melia azedarach by top-bottom green synthetic route. The confirmation of yellowish liquid of synthesized silver nanoclusters was done by UV/Vis spectroscopy. After the calcination of liquid silver nanoclusters at 550°C, green powdered AgNCs were further characterized for their metallic nature, size, and morphology by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), nanoZetasizer (NZ) and Fourier Transform Infrared Spectroscopy (FT-IR) respectively. Phytochemical analysis of leaves extract reveals that the hydrolyzable phenolic acids bioactive molecules are responsible for the reduction of silver metal ion to silver nanoclusters. The silver nanoclusters in presence of sodium borohydride reducing agent were utilized as a catalyst for degradation of toxic organic dyes into their non-toxic derivatives. The catalytic reactions were done under controlled temperature and pH conditions and were characterized by Fourier Transform Infrared Spectroscopy

Synthesis of silver nanoclusters in colloidal scaffold for biolabeling and antimicrobial applications

A robust method to prepare silver nanoclusters (AgNCs) inside a methacrylic acid-ethyl acrylate (MAA-EA) nanogel is proposed, where AgNCs were produced within the nanogel scaffold via UV-photoreduction. The impact of UV irradiation time on the formation of AgNCs and their application in biolabeling and antimicrobial properties were examined. The AgNCs formation is described by two stages; (1) Agn (n = 2–8) nanoclusters formation between 0 and 25 min, and (2) larger silver nanoparticles (AgNPs) formed via aggregation inside the nanogel. The antimicrobial performance depended on the size and concentration of silver ions (Ag+). A maximum inhibitory concentration (MIC) of 1.1 ppm was observed for antimicrobial test with yeast, and a MIC of 11 and 22 ppm was recorded for Escherichia. coli and Staphylococcus aureus respectively. Combining with the green illumination property of AgNCs (emitted at 525 nm) with dead yeast, it could be used for biolabeling. By tuning the size through photoirradiation, the nanogel templated AgNCs is a promising candidate for antimicrobial and biolabeling applications.

Synthesis of silver nanoclusters by irradiation reduction and detection of Cr3+ ions.

In our work, a simple and fast synthesis method is provided to synthesize silver nanoclusters (AgNCs). In this method, with using polyacrylic acid (PAA) as a template, the silver ions were reduced to silver nanoclusters by irradiation reduction at room temperature. The prepared silver nanoclusters (PAA-AgNCs) with average particle size of 1.98 ± 0.79 nm have a fluorescence property, and their physical and chemical properties can be controlled by absorbed dose, PAA/Ag+ mole ratio and other factors. The fluorescence stability of the PAA-AgNCs is good, and it is unique in that the fluorescence emission of the s PAA-AgNCs depends on the excitation wavelength. In addition, based on the fluorescence quenching phenomenon of PAA-AgNCs in the presence of Cr3+ ion, we established a simple and efficient method for the detection of Cr3+ ion by using PAA-AgNCs as fluorescent probes.

Green synthesis of silver nanoclusters via Melia azedarach plant and their potential towards catalytic reduction of 4-nitrophenol

Biomolecules present in the plant extracts have potential to reduce metal ions to nanoclusters by a single-step green synthesis approach. In the current study, we have synthesized the silver nanoclusters (AgNCs) from a medicinal plant, Melia azedarach and studied their catalytic activity toward the reduction of 4-nitophenol to 4-aminophenol and organic dyes. Morover, the phytochemical analysis of the plant extract was carried out in order to determine the bioactive compounds present in it. Metallic nature of the synthesized AgNCs was verified by X-ray diffraction study, while their morphology and size of was confirmed by transmission electron microscopy and Zetasizer, respectively. The study revealed that they were 56±2 nm in size and formed clusters. Fourier transformed infrared spectroscopy gives information about the different functional groups present in synthesized these NCs. Furthermore, the important catalytic applications, such as catalytic reduction of 4-nitrophenol in the presence of mild reducing agent NaBH4 and the catalytic degradation of organic dyes was monitored by FTIR. Therefore, these results indicate that the obtained nanomaterials have important applications in industrial areas.
 
 KEY WORDS: Green synthesis, Silver nanoclusters, Catalytic reduction, Characterization
 
 Bull. Chem. Soc. Ethiop. 2021, 35(1), 197-206.
 DOI: https://dx.doi.org/10.4314/bcse.v35i1.17

Synthesis of Silver Nanoclusters Stabilized by pH-Regulated Chromotropic Acid 2R

Synthesis of Silver Nanoclusters Stabilized by pH-Regulated Chromotropic Acid 2R

Ag48(C≡C tBu)20(CrO4)7]: An Atomically Precise Silver Nanocluster Co-protected by Inorganic and Organic Ligands.

The elaborate selection of capping ligands is of great importance in the synthesis of atomically precise metal nanoclusters. Organic thiolates, alkynyls, phosphines, and/or their combinations are the ligands most widely utilized to protect metal nanoclusters, while inorganic oxo anions have been almost neglected in this field. Herein, the first CrO42-/ tBuC≡C- co-capped Ag48 nanocluster (SD/Ag48, SD = SunDi) was synthesized and structurally characterized by single-crystal X-ray diffraction. The pseudo-5-fold symmetric metal skeleton of SD/Ag48 shows a core-shell structure composed of a Ag23 cylinder encircled by an outer Ag25 shell. Unprecedentedly, coexistence of inorganic (CrO42-) and organic ( tBuC≡C-) ligands was observed on the surface of SD/Ag48. The inorganic CrO42- anion plays three important roles in the construction of silver nanoclusters: (i) passivating the Ag23 kernel; (ii) connecting the core and shell; and (iii) protecting the Ag25 shell. This nanocluster belongs to a 14e superatom system and exhibits successive molecule-like absorption bands from the visible to the ultraviolet region. This work not only establishes a fresh inorganic ligand strategy in the synthesis of silver nanoclusters but also provides a new insight into the important surface coordination chemistry of CrO42- in the shape control of silver nanoclusters.

Synthesis of Fluorescent Ag Nanoclusters for Sensing and Imaging Applications

Metal nanoparticles have attracted more and more attention in the last years due to their unique chemical and physical properties which are very different from the metal bulk material. In particular, when the size of nanoparticles decreases below two nm, nanoparticles can be described as nanoclusters (NCs), and they present peculiar optical properties. The excited electrons in addition to specific absorption bands show also a bright luminescence related to the quantum size effect which produce discrete energy levels. Optical properties (absorption and fluorescence) of these NCs are widely used in many different applications in science and engineering, such as chemical sensors, fluorescent probes for bio imaging or in environmental issues. In the present study, we report on the synthesis of silver nanoclusters (AgNCs) in aqueous phase using silver nitrate as precursor salt and L-Glutathione (GSH) as stabilizer. AgNCs were characterized using absorption and fluorescence spectroscopy, and transmission electron microscopy (TEM). The strong absorption and luminescence shown by these NCs are very promising for a possible exploitation both as label for bioimaging and for optical sensors for heavy metal ions.

A versatile biosensing system for DNA-related enzyme activity assay via the synthesis of silver nanoclusters using enzymatically-generated DNA as template

In the present day, oligonucleotide-encapsulated silver clusters (DNA–AgNCs) have been widely applied into bio-analysis as a signal producer. Herein, we developed a novel method to synthesize DNA–AgNCs encapsulated by long-chain cytosine (C)-rich DNA. Such DNA was polymerized in a template-free way by terminal deoxynucleotidyl transferase (TdT). We demonstrated that TdT-polymerized long chain C-rich DNA can serve as an excellent template for AgNCs synthesis. Based on this novel synthesis strategy, we developed a label-free and turn-on fluorescence assay to detect TdT activity with ultralow limit of detection (LOD) of 0.0318U and ultrahigh signal to background (S/B) of 46.7. Furthermore, our proposed method was extended to a versatile biosensing strategy for turn-on nucleases activity assay based on the enzyme-activated TdT polymerization. Two nucleases, EcoRI and ExoIII as model of endonuclease and exonuclease, respectively, have been detected with high selectivity and competitive low LOD of 0.0629U and 0.00867U, respectively. Our work demonstrates the feasibility of TdT polymerization-based DNA–AgNCs synthesis strategy as a versatile and potent biosensing platform to detect the activity of DNA-related enzymes.

Synthesis of silver nanoclusters, characterization and application to trace level sensing of nitrate in aqueous media

We report here the synthesis of surfactant stabilized silver nanoclusters onto a silver disc electrode by simple potentiostatic method. Characterization of silver nanoclusters by spectral (UV–vis, fluorescence, matrix-assisted laser desorption ionization time-of-flight mass spectroscopy (MALDI-TOF-MS), energy dispersive X-ray spectroscopy (EDX)), morphological (transmission electron microscopy (TEM)) and electrochemical techniques is described. The silver nanocluster modified electrode is used for square wave voltammetric sensing of traces of nitrate. The results of electroanalytical experiments reveal that the designed sensor has a very low detection limit of 1.5×10−15moldm−3 and wide linear response range from 1×10−14 to 1×10−7moldm−3 with R2 value of 0.9936 for nitrate. The sensor shows a good precision of 1.2% (n=3) at 10−12moldm−3 of nitrate. Electrocatalytic studies undertaken with AgNC modified electrode in 0.1moldm−3 NaH2PO4 buffer solution (pH 4.5) containing 10−8moldm−3 NO3− by scan rate variation and single step chronoamperometric studies.

Mass-spectrometric study of the formation of silver nanoclusters in polyether media: 2. Fast atom bombardment and modeling

Within the problem of the synthesis of silver nanoclusters and nanoparticles in polyether media, systems containing silver nitrate AgNO3 and low-molecular-weight polyethers, poly(ethylene glycol) PEG-400 or oxyethylated glycerol OEG-5, were studied by fast atom bombardment (FAB) mass spectrometry. The formation of stable clusters of polyether oligomers (M m ) with silver cations M m · Ag+ was shown, in agreement with the previous data of laser desorption/ionization. Quantum-chemical DFT calculations have shown that the M m · Ag+ clusters are stabilized by wrapping of the polyether chain around the silver cation with the cation coordinating ether oxygen atoms. Silver nanoclusters were not found in the FAB mass spectra of liquid systems, but Ag n + clusters were detected for silver nanoparticles separated from the reaction medium. No products of chemical transformations of PEG-400 or OEG-5 were observed by FAB. A plausible mechanism of the reduction of silver cations involving nitrate anions is discussed.

Synthesis of Silver Nanoclusters and Functionalization with Glucosamine for Glyconanoparticles

Functionalized nanoparticles are promising candidates for the construction of new nanomaterials. In this paper, glucosamine was covalently functionalized on the surface of silver nanoparticles to fabricate glyconanoparticles. Silver nanoclusters obtained by liquid-solid-solution (LSS) strategy under hydrothermal condition were first functionalized by carboxyl-terminated alkanethiol and the terminal carboxyl group was subsequently bonded with side-chain amino group of glucosamine surface through EDC/NHS coupling reaction. UV-vis spectrometer and EDXA measurements ensure the formation of silver nanoparticles. The surface functionalization of glucosamine on silver nanoparticles was confirmed from the carbonyl group of secondary amide linkage obtained by the conjugation of NHS terminated silver nanoparticles and amino group of glucosamine. This is evinced from the FT-IR characteristic stretching at 1637cm− 1 and 1H-NMR chemical shift from 8.4 to 7.6 ppm, respectively. Morphological images (FE-SEM and AFM) reveal the size and shape of the silver nano-assembly and silver-glucosamine nanoparticles. The fabricated glyconanoparticles with 15 ± 5 nm size can be easily suspended in water, stable over a broader range of pH and would be useful for variety of glyconanotechnology.

Synthesis of silver nanoclusters on zeolite substrates

Silver nanoclusters were synthesized by reducing silver nitrate with ethylene glycol at 160 °C in the presence of zeolite. A one-pot procedure has rendered uniform size distributions of quasispherical silver clusters of average sizes of 100–200 nm synthesized on the surfaces of cubiclike zeolite substrates of ∼1 μm side. Bulk material microanalysis measurements showed samples with silver mass percentages of 20%–38%. Surface atomic composition analysis found silver concentrations of 3.1%–5.7%, zeolite compounds and nontraces of nitrogen were measured. The binding energy for the Ag 3d5/2 core electrons was shifted to higher energies at 368.6 eV compared to that of metallic silver. Herein, is presented a cost-effective technique for producing a narrow size distribution of silver nanocomposites with great potential for optoelectronics, catalysis, and nanobiotechnological applications.

Synthesis of silver nanoclusters in starch aqueous solutions

The capability of aqueous starch solution for reduction of Ag+ ions and stabilization of metallic silver nanoparticles was examined. Kinetic parameters of formation of Ag nanoparticles were determined.