Metal Nanoparticles In Solution Research Articles

A Review on Metallic Nanoparticles

Metallic nano-particles are nano scale metals that fall between one to one hundred nano meters in length, breadth, and thickness. Faraday looked into the possibility of metallic nanoparticles in solution for the first time in 1856. These days, it is possible to create and modify these nanomaterials with different chemical functional groups, enabling them to engage with medicines, ligands, and antibodies. Applications for metallic nanoparticles in biotechnology, therapeutics, and medication and gene delivery are numerous. The features, benefits, drawbacks, and attributes of metal nanomaterials are outlined in this review. This review also highlights how metallic nanomaterials work as catalysts, which is necessary for stabilization. It provides the readers with detailed information on the synthesis by various methods and characterization, with a particular focus on therapeutic application along with potential side effects and their future perspectives. Recent headway has opened the way to site-specific targeting and drug delivery by these metallic nano particles. Keywords: Surface Atom and Quantum Dot, Metal Nano particle, Gold, Platinum, and Silver Nano particle, Catalyst.

Synthesis of Metallic Nanostructures Using Ionizing Radiation and Their Applications.

This paper reviews the radiation-induced synthesis of metallic nanostructures and their applications. Radiolysis is a powerful method for synthesizing metallic nanoparticles in solution and heterogeneous media, and it is a clean alternative to other existing physical, chemical, and physicochemical methods. By varying parameters such as the absorbed dose, dose rate, concentrations of metallic precursors, and nature of stabilizing agents, it is possible to control the size, shape, and morphology (alloy, core-shell, etc.) of the nanostructures and, consequently, their properties. Therefore, the as-synthesized nanoparticles have many potential applications in biology, medicine, (photo)catalysis, or energy conversion.

Universal Chiral-Plasmon-Induced Upward and Downward Transfer of Circular Dichroism to Achiral Molecules.

Electromagnetic chirality transfer represents an effective means of the nanoscale manipulation of optical chirality. While most of the previous reports have exclusively focused on the circular dichroism (CD) transfer from UV-responsive chiral molecules toward visible-resonant achiral colloidal nanoparticles, here we demonstrate a reverse process in which plasmonic chirality can be transferred to achiral molecules, either upward from visible to UV or downward from visible to near infrared (NIR). By hybridizing achiral UV- or NIR-responsive dye molecules with chiral metal nanoparticles in solution, we observe a chiral-plasmon-induced CD (CPICD) signal at the intrinsically achiral molecular absorption bands. Full-wave electromagnetic modeling reveals that both near-field Coulomb interaction and far-field radiative coupling contribute to the observed CPICD, indicating that the mechanism considered here is universal for different material systems and types of optical resonances. Our study provides a set of design guidelines for broadband nanophotonic chiral sensing from the UV to NIR spectral regime.

(Invited) Direct Laser Induced Gold Wiring of 2D Materials with Sub-Μm Resolution

One of the most influential technologies of our modern world are integrated electronics. Almost all parts of our daily life include some bearing with any kind of electrical technologies. The fabrication methods itself, for integrated miniatured electrical devices have had not much innovation in terms of production. Several processing steps still mainly consist of different kinds of lithography. This situation may change with new challenges on the production of smaller quantities with specialized functions, or the use of temperature critical or atomically thin surfaces, where the thermal evaporation of metals damages the sample.For some decades now, printing of all types of electronics have gained great attraction. While lithography is a time-consuming multi-step process (including resist preparation, illuminating, developing, evaporation and lift-off) with expensive and harmful photoresists and harsh environmental conditions (high-vacuum and thermal treatments), ink printing allows for direct and simple application of the desired structures [1]. Two main types of inks are typically applied: colloidal solutions of metal nanoparticles [2, 3] or metal-organic precursor solutions [4]. In both cases, thermal curing after deposition is required to achieve metallic conduction. To this end, laser writing is often advantageous over thermal sintering due to the overall lower thermal stress applied to the material, particularly on flexible, thermally sensitive substrates [5] whereas metal nanoparticles suffer from a relatively high photothermal stability and the need for a large laser power to achieve sufficient sintering [3]. In contrast, metal-organic precursor solutions feature a relatively low metal content (≤34 wt-%)10, and undergo large volume contractions during laser writing. These challenges have so far prevented the definition of metallic gold contacts with diffraction-limited feature sizes by ink printing and laser writing.Here, we introduce atomically-precise, metalloid Au32(nBuP12Cl8) nanoclusters (Au32NCs) [6] as an ink for resistless, direct laser writing of metallic gold micro- and nanostructures. The unique advantages of this ink over Au nanoparticles or typical metal-organic Au precursors are their high photosensitivity in combination with a large gold content of 70 wt-%. This allows for writing gold structures with feature sizes of 250 nm and line spacings < 200 nm using 1.86 mW laser power at 488 nm with a scan speed of 0.1 mm/s. We apply this method on a wide range of substrates, including flexible polymer membranes, find metallic conductance with conductivities ~ 1 × 106 S/m and demonstrate that defining such Au contacts on two-dimensional semiconductors results in fully functional optical switches and field effect transistors made out from 2D materials.[1] Raut NC. et al., Jour. Mat. Chem. C 2018, 6(7): 1618-1641.[2] Ko E. et al., Nanotechnology 2007, 18(34): 345202.[3] Hong S. et al., ACS Nano 2013, 7(6): 5024-5031.[4] Schoner C et al., Thin Solid Films 2013, 531: 147-151.[5] Skylar-Scott MA et al., PNAS 2016, 113(22): 6137-6142.[6] Kenzler S et al., Angew. Chem. Int. Ed. 2019, 58(18): 5902-5905. Figure 1

Synthesis of Metal Nanoparticles via Pulicaria undulata and an Evaluation of Their Antimicrobial, Antioxidant, and Cytotoxic Activities

Nanoparticle engineering via plants (green synthesis) is a promising eco-friendly technique. In this work, a green protocol was applied to the preparation of silver, zinc, and selenium nanoparticle solutions supported by the extracted aerial parts of Pulicaria undulata. The formation of nanoparticles in the solution was characterized using phytochemical analysis, and UV-visible, TEM, and zeta-potential spectroscopy. In addition, various biological activities were investigated for the extract of P. undulata and the produced nanoparticles (selenium, silver, and zinc), including antioxidant, antimicrobial, and cytotoxic activities. The volatile components of the extracted constitute verified the fact that twenty-five volatile components were characterized for the majority of abundant categories for the fatty acids, esters of fatty acids (59.47%), and hydrocarbons (38.19%) of the total area. The antioxidant activity of P. undulata extract and metal nanoparticles was assessed using DPPH assay. The results indicated reduced potency for the metal nanoparticles’ solutions relative to the results for the plant extract. The cytotoxicity of the investigated samples was assessed using an MTT assay against various tumor and normal cell lines with improved cytotoxic potency of the solutions of metal nanoparticles, compared to the plant extract. The antimicrobial activity was also estimated against various bacterial and fungal species. The results confirmed amended potency for inhibiting the growth of microbial species for the solutions of metal nanoparticles when compared to the extracted aerial parts of the plant. The present study showed that green synthetized nanoparticles using P. undulata have various potential bioactivities.

Biosynthesis, characterization, and cytotoxic activities of zinc nanoparticles (ZnNPs) using Euphorbia retusa extract

Biosynthesis zinc oxide nanoparticles (ZnO-NPs) were produced from aqueous extracts of Euphorbia retusa, and their volatile components and antioxidant and cytotoxic characteristics were examined. Various methods, including UV–visible, TEM, and zeta potential spectroscopy, were used to characterize the ZnO-NPs. The GC/MS spectrum analysis was used to determine the plant extract's volatile components as well as the metal nanoparticles from this plant's antioxidant and cytotoxic characteristics. The results of GC–MS analysis demonstrated that twenty components were recorded on the identified scale; the most prevalent molecule, accounting for 29.25% of the overall composition, is methyl oleate. Hydrocarbons (13.84%), fatty acids, and esters of fatty acids (78.72%) are classified as the primary class. By using the DPPH test, the scavenging activity of metal nanoparticles and E. retusa extract was estimated. In comparison to the effects of plant extract, the results for the metal nanoparticle solutions showed diminished effectiveness. The MTT test was used to compare the cytotoxic potential of the solutions with metal nanoparticles and the plant extract on both tumor cell lines and healthy cell lines. ZnO-NPs from E. retusa inhibited microbial growth better than the plant extract, making them interesting biomedical and environmental options.

Packaging of DNA Integrated with Metal Nanoparticles in Solution.

The transformation of high-molecular DNA from a random swollen coil in a solution to a discrete nanosized particle with the ordered packaging of a rigid and highly charged double-stranded molecule is one of the amazing phenomena of polymer physics. DNA condensation is a well-known phenomenon in biological systems, yet its molecular mechanism is not clear. Understanding the processes occurring in vivo is necessary for the usage of DNA in the fabrication of new biologically significant nanostructures. Entropy plays a very important role in DNA condensation. DNA conjugates with metal nanoparticles are useful in various fields of nanotechnology. In particular, they can serve as a basis for creating multicomponent nanoplatforms for theranostics. DNA must be in a compact state in such constructions. In this paper, we tested the methods of DNA integration with silver, gold and palladium nanoparticles and analyzed the properties of DNA conjugates with metal nanoparticles using the methods of atomic force microscopy, spectroscopy, viscometry and dynamic light scattering. DNA size, stability and rigidity (persistence length), as well as plasmon resonance peaks in the absorption spectra of systems were studied. The methods for DNA condensation with metal nanoparticles were analyzed.

Modulating incident light for improved CO2 photoreduction in freestanding silver bismuth iodide/nanocellulose films with exotic gold nanoparticles

In response to the severe climate change caused by significant carbon dioxide emissions, researchers have been exploring the conversion of CO2 into carbon-based fuels through photocatalytic reactions inspired by photosynthesis. Particulate photocatalysts are known for their easy fabrication and diverse material configuration, with immobilization onto composite polymers enhancing reusability and practicality. In this study, we fabricated a novel freestanding photocatalyst composite film by immobilizing Ag3BiI6 (SBI) onto a nanocellulose (CNF) transparent film using a sequential process involving noble metal nanoparticle solutions and thermal evaporation of BiI3. The effect of the sequence and composition of Au and SBI/CNF on the morphology, optical property, and CO2 photoreduction performance was also investigated. The resulting SBI-Au/CNF film exhibited the highest photocatalytic activity for CO2 reduction, achieving a CO yield of 31.96 μmol/g⋅h with high stability for long-term photocatalytic reactions lasting 72 h. This study demonstrates the potential of photocatalytic materials to mitigate climate change by converting CO2 emissions into useful fuels.

Surfactant- and Ligand-Free Synthesis of Platinum Nanoparticles in Aqueous Solution for Catalytic Applications

The synthesis of surfactant-free and organic ligand-free metallic nanoparticles in solution remains challenging due to the nanoparticles’ tendency to aggregate. Surfactant- and ligand-free nanoparticles are particularly desirable in catalytic applications as surfactants, and ligands can block access to the nanoparticles’ surfaces. In this contribution, platinum nanoparticles are synthesized in aqueous solution without surfactants or bound organic ligands. Pt is reduced by sodium borohydride, and the borohydride has a dual role of reducing agent and weakly interacting stabilizer. The 5.3 nm Pt nanoparticles are characterized using UV-visible spectroscopy and transmission electron microscopy. The Pt nanoparticles are then applied as catalysts in two different reactions: the redox reaction of hexacyanoferrate(III) and thiosulfate ions, and H2O2 decomposition. Catalytic activity is observed for both reactions, and the Pt nanoparticles show up to an order of magnitude greater activity over the most active catalysts reported in the literature for hexacyanoferrate(III)/thiosulfate redox reactions. It is hypothesized that this enhanced catalytic activity is due to the increased electron density that the surrounding borohydride ions give to the Pt nanoparticle surface, as well as the absence of surfactants or organic ligands blocking surface sites.

Bioinspired Manufacturing: Photoinduced Self-Replication of Metal Nanoparticles in Solution and on Surfaces

Bioinspired Manufacturing: Photoinduced Self-Replication of Metal Nanoparticles in Solution and on Surfaces

Synthesis of Highly Accessible and Reactive Sites in Gold Nanoparticles Using Bound Bis(Diphenylphosphine) Ligands.

While bound organic ligands provide steric protection against aggregation for metallic nanoparticles in solution, they can block a large fraction of the surface atoms which are needed for binding in catalysis and sensing applications. In this work, highly accessible Au nanoparticles ligated with bis(diphenylphosphine) molecules are synthesized and characterized in solution. Characterization is performed using high angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), ultraviolet-visible (UV-Vis) spectroscopy, and fluorescence chemisorption experiments. These synthesized nanoparticles are accessible to a 2-napthalenethiol (2-NT) probe molecule in solution. The highest 2-NT accessibility is observed when using 1,1-bis(diphenylphosphino)methane (dppm) ligand where 61 % of the total gold atoms are accessible. It is hypothesized that increasing the rigidity of the bis(diphenylphosphine) ligand increases the number of binding sites on the Au nanoparticles. These nanoparticles are catalytically active for resazurin reduction, and the resazurin reduction rate scales with the number of binding sites.

High-fluence and high-gain multilayer focusing optics to enhance spatial resolution in femtosecond X-ray laser imaging

With the emergence of X-ray free-electron lasers (XFELs), coherent diffractive imaging (CDI) has acquired a capability for single-particle imaging (SPI) of non-crystalline objects under non-cryogenic conditions. However, the single-shot spatial resolution is limited to ~5 nanometres primarily because of insufficient fluence. Here, we present a CDI technique whereby high resolution is achieved with very-high-fluence X-ray focusing using multilayer mirrors with nanometre precision. The optics can focus 4-keV XFEL down to 60 nm × 110 nm and realize a fluence of >3 × 105 J cm−2 pulse−1 or >4 × 1012 photons μm−2 pulse−1 with a tenfold increase in the total gain compared to conventional optics due to the high demagnification. Further, the imaging of fixed-target metallic nanoparticles in solution attained an unprecedented 2-nm resolution in single-XFEL-pulse exposure. These findings can further expand the capabilities of SPI to explore the relationships between dynamic structures and functions of native biomolecular complexes.

Advanced quantitative analysis of colloidal solution of metal nanoparticles produced by laser ablation in liquids

The diameter of laser synthesized colloidal nanoparticles can be derived from a volume of ablated material and absorbance at surface plasmon resonance wavelength. The origin of such nanoparticles’ diameter is studied in this work. The study is based on Beer-Lambert law where nanoparticle size-distribution and UV-Vis photoabsorbance data are used. Theoretically modeled diameter is verified by independent integral approach proving that simple model derived in our previous work is by most means usable for determination of diameter of laser synthesized nanoparticles in colloidal solution with sizes less than SPR wavelength. Here is also presented the mathematical proof which indicates that in monodisperse limit, under assumption that size-distribution of synthesized nanoparticles can be described by log-normal function, diameter obtained by simple analytical model is in fact mode diameter (most frequent diameter) of size-distribution. Furthermore, it is shown that mode diameter of size-distributions can be obtained from volume average diameter of nanoparticles over experimentally determined diameter distribution as well as from number average diameter of nanoparticles over the same diameter distribution by multiplication of those diameters with shift factors depended only on standard deviation of log-normal distribution. This is verified for size-distributions obtained independently by AFM, TEM and DLS techniques and is proposed to be universal property of log-normal distribution function.

Controllable electrostatic manipulation of structure building blocks in noble metal aerogels

An electrostatic manipulation method has been presented by directly mixing oppositely charged noble metal nanoparticle solutions to prepare the corresponding noble metal hydrogels without introducing additional reagents.

A quantitative analysis of colloidal solution of metal nanoparticles produced by laser ablation in liquids

A quantitative analysis of colloidal solution of metal nanoparticles produced by laser ablation in liquids

Conformational changes of high-molecular-weight DNA upon binding to noble metal nanoparticles in solution

Conformational changes of high-molecular-weight DNA upon binding to noble metal nanoparticles in solution

Synthesis, Characterization and Size Evaluation of Biosynthesized Silver Nanoparticles by UV–Vis Spectroscopy

Mie-Gans (MG) fitting model theoretical model utilizing the phenomena of scattering light to determine the morphologies, shape, and size of metallic nanoparticles in solution. In the present work, the average radius of biosynthesized silver nanoparticles (AgNPs) was evaluated based on the fitting of their Ultraviolet-visible (UV-Vis) spectra by the MG fitting model for spherical and non-spherical particles. Biosynthesis of AgNPs using Lemon (Citrus Limon) leaves extract as a reducing agent and Gum Acacia as a capping and stabilizing agent was studied for various concentrations of Citrus Limon leaves extract. The investigation of structural and optical properties was carried out for the synthesized samples using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and UV-Vis spectroscopy. XRD confirmed the structure of AgNPs and revealed that the structure of these nanoparticles was face-centered cubic (fcc). FTIR measurements indicate the presence of citric acid in Citrus Limon leaf extract which is responsible for reducing bioreduced AgNPs. UV-Vis spectroscopy determined the surface plasmon resonance (SPR) for AgNPs; the peaks of resonances of samples appear at 436-461nm range. MG fitting evaluations show that most of AgNPs were spherical in shape with an average radius in the range of 39-47nm. Moreover, this model allows the estimation of the fraction of nonspherical and aggregated AgNPs. These unique characteristics of AgNPs have made them applicable in a large number of fields like water treatment, biomedical, energy science, catalysis, etc.

Residual- and linker-free metal/polymer nanofluids prepared by direct deposition of magnetron-sputtered Cu nanoparticles into liquid PEG

Colloidal solutions of metal nanoparticles (NPs) are typically produced by multi-step methods using a variety of chemicals. Resultant nanofluids require extra purification steps to remove the reactions by-products and modification steps to introduce anticoagulants for the solution stabilization. Here, we suggest a single-step method to produce nanofluid in which only two components are present: 22 nm-sized Cu NPs as a filler and polyethylene glycol (PEG, 400 g/mol) as a liquid base. The method employs magnetron sputtering to synthesize Cu NPs in a gas aggregation cluster source and their subsequent loading into vacuum-compatible PEG. The resultant nanofluid demonstrates strong plasmonic and photoluminescent activity, and shows enhanced stability over time, in contrast to conventional colloidal solutions. The approach offers an alternative for the production of nanofluids in which the processes of the NP formation are decoupled from the processes of their mixing with the liquid base.

Spectroscopic characteristics of colloidal solutions of metal nanoparticles

Nanoparticles are finding more and more practical applications in various fields of human activity, including veterinary and medicine. Due to the fact that the effectiveness of activity of colloidal solutions of nanoparticles is directly related to the state of aggregation of nanosized particles, it is urgent to use fast and convenient methods for assessing the physicochemical characteristics of such preparations. Nanoparticles have unique optical properties that depend on their size and shape. They can be determined by the refractive index of the light on the surface of the nanoparticles in a phenomenon known as plasmon resonance, which makes UV-Vis spectroscopy a valuable tool for studying and evaluating the characteristics of nanomaterials. Goal of the study is to study the optical characteristics of several samples of colloids of nanoparticles of noble metals (silver) and bioelements (copper, silicon dioxide) in order to determine the possibility of further application of UV-Vis spectroscopy for evaluation of activity and stability of colloidal solutions of nanoparticles. Commercial preparations based on nanoparticles of noble metals (silver) or bioelements (copper, silicon dioxide) in working dilutions recommended by manufacturers were used to study optical characteristics of the colloidal solutions. Optical density and absorption spectra were determined at the wavelengths (nm): 300-800 nm. The f plasmon surface resonance has been found in all test preparations, while all of them exhibited obvious nonlinear optical properties. The most pronounced plasma resonance peak is found in the colloidal solution of silver nanoparticles within a wavelength of 420 nm. In the case of a colloidal solution of copper nanoparticles, the peak of plasmon resonance was less pronounced and had a red shift (peak at 560 nm). In the colloidal solution of silicon silica, the plasmon resonance was less pronounced than other test preparations, being shifted to the blue side of the spectrum (360 nm).

Evaluation of solution-cathode glow discharge atomic emission spectrometry for the analysis of nanoparticle containing solutions

The Solution Cathode Glow Discharge (SCGD) is a novel atmospheric-pressure glow discharge plasma sustained in the ambient atmosphere that is an appealing alternative to the inductively-coupled plasma as a source for atomic emission spectrometry. Simple, low power, and inexpensive, the SCGD is an attractive source for continuous environmental monitoring applications such as the quantitation of metallic nanoparticle solutions by atomic emission spectrometry. Metallic nanoparticles (NP) with diameters from 5 nm-150 nm were directly analyzed by SCGD-AES and found to exhibit lower, and size-dependent, elemental sensitivity when compared to dissolved free-ion standard solutions. Acid digestion with matrix-matching was shown to be an effective approach to achieve accurate quantitation. The origin of these morphological matrix effects was studied by investigating experimental parameters such as discharge power, solution flow rate, and influence of added surfactants. Examination of the spatial distribution of atomic emission between cathode and anode showed a shift in peak atomic emission towards the anode of the SCGD for some NPs as compared to free-ion solutions. A novel nested capillary design was used to introduce NP into the SCGD without dissolution within the acidic solvent and showed difference in sensitivity from free-ion solutions to be a NP morphological effect. Correlation of NP boiling point with difference in sensitivity between free-ion and NP solutions supports the conclusion that delayed vaporization of nanoparticles is the source of the morphological matrix effect, due primarily to lower rate of vaporization within the SCGD by lower gas temperatures and short residence time. Analysis of NP of different chemical form, and alloyed nanoparticles composed of more than one element, showed correlation with boiling point. Implications of these results on the possible mechanisms by which material is transferred from the liquid cathode into the plasma are considered.