Detail review on chemical,physical and green synthesis,classification, characterizations and applications of nanoparticles

ABSTRACT

Nanotechnology is an emerging field of science. The base of nanotechnology is nanoparticles. The size of nanoparticles ranges from 1 to 100?nm. The nanoparticles are classified into different classes such as inorganic nanoparticles, organic nanoparticles, ceramic nanoparticles and carbon base nanoparticles. The inorganic nanoparticles are further classified into metal nanoparticles and metal oxide nanoparticles.similarly carbon base nanoparticles classified into Fullerene, Carbon nanotubes, Graphene, Carbon nanofiber and carbon black Nanoparticles are also classified on the basis of dimension such as one dimension nanoparticles, two-dimension nanoparticles and three-dimension nanoparticles. The nanoparticles are synthesized by using two approaches like top-down approach and bottom-up approach. In this review chemical, physical and green synthesis of nanoparticles is reported. The synthesized nanoparticles are synthesized using different qualitative and quantitative techniques. The Qualitative techniques include Fourier Transform Infrared Spectroscopy (FT-IR), UV-Vis spectrophotometry, Scanning electron microscope (SEM), X.ray diffraction (XRD) and Atomic Force Microscopy (AFM). The Quantitative techniques include Transmission Electron Microscopy (TEM), Annular Dark-Field Imaging (HAADF) and Intracranial pressure (ICP). The nanoparticles have different application which is reported in this review.     

Silane-based poly(ethylene glycol) as a primer for surface modification of nonhydrolytically synthesized nanoparticles using the Stöber method

This paper describes the use of methoxy-poly(ethylene glycol) silane (MPEG-sil) as a linker molecule for the synthesis of silica-coated nanoparticles by the St?ber method. While short alkane chain-based siloxanes including (acryloxypropyl)trimethoxysilane and 3-methacryloxypropyl-trimethoxysilane are popular molecules used in surface modification, they are not efficient for the silica coating of nanoparticles synthesized from organic solvents containing long carbon chain carboxylic acids or amines as capping agents. Here, we report the utilization of MPEG-sil to bridge this gap. Our approach is based on a two-phase system, in which ligand exchange takes place in a hydrophobic environment and the surface modification with silica is conducted in an ethanol-water mixture. Our results show that this two-phased approach was effective to coat monodisperse Fe2O3 nanoparticles capped with oleic acid and Ag nanoparticles capped with oleylamine with uniform SiO2 shells. The process was also demonstrated for double-shell nanostructures to produce SiO2-coated Pt@Fe2O3 core-shell nanoparticles. The results described in this work represent a new approach for the surface modification with silica coating of monodisperse nanoparticles synthesized from nonhydrolytic solutions and can potentially have a broad ramification in the development of water-dispersible nanoparticles for biological applications.     

Free-radical cross-linking of serum albumin molecules on the surface of magnetite nanoparticles in aqueous dispersion

A novel universal approach to cross-linking of protein macromolecules on the surface of magnetite nanoparticles has been developed. The approach is based on protein liability to free-radical modification, leading to the formation of intermolecular covalent cross-links. Free radicals are locally generated on the surface of nanoparticles. Stable coatings of serum albumin 3 nm thick are formed on the surface of magnetite nanoparticles. Using a set of physicochemical methods, it has been proven that stable coatings composed of protein macromolecules are formed around individual nanoparticles. The presence of reactive groups in the protein structure makes it possible to perform subsequent modification of the surface layers-in particular, to graft nonprotein drugs. The approach developed can be used to create superfine systems with desired surface properties for targeted delivery of drugs and biologically active substances.     

Fabrication of ordered catalytically active nanoparticles derived from block copolymer micelle templates for controllable synthesis of single-walled carbon nanotubes

We report the use of the block copolymer micelle approach to produce various transition metal nanoparticles such as iron, cobalt, and nickel with precisely controlled size and spacing. These uniformly sized catalyst nanoparticles derived from the block copolymer micelle approach have enabled the synthesis of carbon nanotubes (CNTs) with narrow size distribution. Because of the excellent film forming ability of the polymeric material, metal-bearing surface micelles produced from the solution micelles can be distributed uniformly on a surface, resulting in evenly dispersed catalyst nanoparticles. As a result, high quality and uniformly distributed CNTs have been synthesized. Spatially selective growth of CNTs from a lithographically patterned metal-bearing micelle film has been achieved. The polymer template approach can potentially be extended to synthesize single-metallic and bimetallic catalytically active nanoparticles with uniform size and spacing and is fully compatible with conventional lithographic process. Additionally, catalyst nanoparticles produced from this method do not coalesce at high growth temperature. All these attributes make this approach a promising fabrication pathway for controllable synthesis of CNTs.     

Measuring the number concentration of arbitrarily-shaped gold nanoparticles with surface plasmon resonance microscopy

Molar concentration of gold nanoparticles is one of the most critical parameters of gold colloids in order to develop their applications in sensing, diagnostics and nanomedicine. Previous methods often stand just for gold nanoparticles with regular shape and narrow size distribution. In the present work, we proposed an absolute quantification method that determined the molar concentration of gold nanoparticles with arbitrary shapes and polydisperse sizes. This approach involved the real time monitoring and counting of individual nanoparticles collision events, from which the quantification of molar concentration was achieved using a theoretical model consisting of Fick’s laws of diffusion and Stokes-Einstein equation. The determination of spherical gold nanoparticles concentration resulted in excellent agreement with traditional spectrometry method. It was further demonstrated that the present approach can be expanded to determine the molar concentration of gold nanoparticles with arbitrary shapes and poly-diversed distributions.     

Catalyzed radical polymerization of styrene vapor on nanoparticle surfaces and the incorporation of metal and metal oxide nanoparticles within polystyrene polymers

We present a novel approach to polymerize olefin vapors on the surfaces of metallic and semiconductor nanoparticles. In this approach, a free radical initiator such as AIBN is dissolved in a volatile solvent such as acetone. Selected nanoparticles (prepared separately using the laser vaporization-controlled condensation method) are used to form initiator-coated nanoparticles placed on a glass substrate. The olefin (styrene) vapor is polymerized by the thermally activated initiator on the nanoparticle surfaces. Our approach also provides structural and mechanistic information on the early stages of catalyzed gas-phase polymerization, which can be used to correlate the gas-phase structural properties with the bulk properties and the performance of the polymer nanocomposites. This correlation is the key step in controlling the properties of the polymer nanocomposites. Our results clearly demonstrate the success of this method in preparing polymer coated nanoparticles for a variety of interesting applications. The precise control of the chemical functionality, thickness, and morphology of the polymer film and the size, size distribution, and properties of the core nanoparticles (photoluminescence, magnetic) may lead to major technological breakthroughs in a variety of applications including drug delivery, ultrasensitive detectors, and chemical and biological sensors.     

Magnetically Induced Continuous CO2 Hydrogenation Using Composite Iron Carbide Nanoparticles of Exceptionally High Heating Power

The use of magnetic nanoparticles to convert electromagnetic energy into heat is known to be a key strategy for numerous biomedical applications but is also an approach of growing interest in the field of catalysis. The heating efficiency of magnetic nanoparticles is limited by the poor magnetic properties of most of them. Here we show that the new generation of iron carbide nanoparticles of controlled size and with over 80 % crystalline Fe_2.2C leads to exceptional heating properties, which are much better than the heating properties of currently available nanoparticles. Associated to catalytic metals (Ni, Ru), iron carbide nanoparticles submitted to magnetic excitation very efficiently catalyze CO₂ hydrogenation in a dedicated continuous‐flow reactor. Hence, we demonstrate that the concept of magnetically induced heterogeneous catalysis can be successfully applied to methanation of CO₂ and represents an approach of strategic interest in the context of intermittent energy storage and CO₂ recovery.     

Biotinylated thermoresponsive core cross-linked nanoparticles via RAFT polymerization and "click" chemistry

A straightforward approach to the synthesis of "clickable" thermoresponsive core cross-linked (CCL) nanoparticles was developed. This approach was based on reversible addition-fragmentation chain transfer (RAFT) radical cross-linking polymerization of styrene and divinylbenzene with azide-functionalized poly(N-isopropylacrylamide) (PNIPAM-N(3)) as macro chain transfer agent in a selective solvent. Spherical nanoparticles with a diameter of 12nm were obtained after 24h polymerization. When the lyophilized CCL nanoparticles were dispersed in THF, spherical nanoparticles were observed, confirming the stability of CCL nanoparticles. The transmission electron microscopy (TEM) studies demonstrated that spherical nanoparticles and wormlike structure coexisted in the aqueous solution. The CCL nanoparticles have a lower critical solution temperature (LCST) at about 29.6°C, a little lower than that of PNIPAM homopolymer. Biotin molecules were conjugated to the surface of CCL nanoparticles via "click" chemistry in aqueous media. After bioconjugation, the LCST shifted to 28.3°C. The bioavailability of biotin to protein avidin was evaluated by a 4'-hydroxyazobenzene-2-carboxylic acid/avidin (HABA/avidin) binding assay and TEM.     

Aqueous-organic phase transfer of gold nanoparticles and gold nanorods using an ionic liquid

The water-immiscible ionic liquid, [C4MIM][PF6], is a solvent medium that allows complete transfer of gold nanoparticles from an aqueous phase into an organic phase. Both spherical and rod-shaped gold nanoparticles are efficiently transferred from an aqueous solution into the organic phase without requiring the use of thiols. The sizes and shapes of the gold nanoparticles were preserved during the phase-transfer process when a surfactant was added to the ionic liquid. This process offers a simple approach for obtaining solutions of differently sized and shaped gold nanoparticles in ionic liquids.     

The effect of electrocatalytic nanoparticle injection on the electrochemical response at a rotating disc electrode

A new approach to study electrocatalytic oxidation of glucose is proposed. As opposed to numerous studies on electrodes modified with gold nanoparticles this reaction was studied in their suspension of gold nanoparticles under hydrodynamic conditions on a noncatalytic glassy carbon rotating disc electrode. It has been shown that addition of nanogram amount of positively charged Au nanoparticles results in a clear current response, whereas no clear response is seen for negatively charged ones. This effect results from the electrocatalytic oxidation of glucose on Au nanoparticles mainly adsorbed on glassy carbon electrode. The role of electrode preparation method on reproducibility of the results is emphasized.     

Covalent Grafting of Coordination Polymers on Surfaces: The Case of Hybrid Valence Tautomeric Interphases

We have developed a novel approach for grafting coordination polymers, structured as nanoparticles bearing surface reactive carboxylic groups, to amino‐functionalized surfaces through a simple carbodiimide‐mediated coupling reaction. As a proof‐of‐concept to validate our approach, and on the quest for novel hybrid interphases with potential technological applications, we have used valence tautomeric nanoparticles exhibiting spin transition at or around room temperature. SEM and AFM characterization reveal that the nanoparticles were organized chiefly into a single monolayer while X‐ray photoelectron spectroscopy (XPS) measurements confirm that the nanoparticles retain a temperature‐induced electronic redistribution upon surface anchorage. Our results represent an effective approach towards the challenging manufacture of coordination polymers.     

Reversible Magnetic Agglomeration: A Mechanism for Thermodynamic Control over Nanoparticle Size

We present a method for the synthesis and precise size control of magnetic nanoparticles in a reversible magnetic agglomeration mechanism. In this approach, nanoparticles nucleate and grow until a critical susceptibility is reached, in which magnetic attraction overcomes dispersive forces, leading to agglomeration and precipitation. This phase change in the system arrests nanoparticle growth and gives true thermodynamic control over the size of nanoparticles. We then show that increasing the alkyl chain length of the surfactant, and hence increasing steric stabilization, allows nanoparticles to grow to larger sizes before agglomeration occurs. Therefore, simply by choosing the correct surfactant, the size and magnetic properties of iron nanoparticles can be tailored for a particular application. With the continuous addition of the precursor solution, we can repeat the steps of nucleation, growth, and magnetic agglomeration indefinitely, making the approach suitable for large scale syntheses.     

"Liquid-phase calcination" of colloidal mesoporous silica nanoparticles in high-boiling solvents

We report on a novel high temperature liquid phase "calcination" method with trioctylphosphine oxide (TOPO), tri-n-octylamine (TOA), and squalene for removing the template and strengthening the silica network in colloidal mesoporous silica (CMS) nanoparticles. For such materials, the common calcination procedure in air would result in strong agglomeration, thus preventing their use in colloidal suspensions. The highest efficiency of the new approach is obtained by thermal calcination in TOPO at only 275 °C, as shown by an increasing degree of silica condensation, and the retention of the high colloidal stability of the CMS nanoparticles. Moreover, we also show the ability of the TOPO treatment to remove the template, thus saving a preparation step. The resulting CMS nanoparticles retain the ordered mesostructure, high porosity, and large surface area of the original mesoporous nanoparticles, while showing a much greater degree of silica condensation and high stability. The concept of "liquid calcination" represents a powerful general approach for the preparation of stable colloidal porous nanoparticles.     

Synthesis of carbon-encapsulated iron nanoparticles via solid state reduction of iron oxide nanoparticles

The encapsulation of iron nanoparticles in protective carbon cages leads to unique hybrid core-shell nanomaterials. Recent literature reports suggest that such nanocomposites can be obtained in a relatively simple process involving the solid state carbothermal reduction of iron oxide nanoparticles. This approach is very attractive because it does not require advanced equipment and consumes less energy in comparison to widely used plasma methods. The presented more-in-depth study shows that the carbothermal approach is sensitive to temperature and the process yield strongly depends on the morphology and crystallinity of the carbon material used as a reductant.     

Molecularly Designed Nanoparticles by Dispersion of Self‐Assembled Organosiloxane‐Based Mesophases

The design of siloxane‐based nanoparticles is important for many applications. Here we show a novel approach to form core–shell silica nanoparticles of a few nanometers in size through the principle of “dispersion of ordered mesostructures into single nanocomponents”. Self‐assembled siloxane–organic hybrids derived from amphiphilic alkyl‐oligosiloxanes were postsynthetically dispersed in organic solvent to yield uniform nanoparticles consisting of dense lipophilic shells and hydrophilic siloxane cores. In situ encapsulation of fluorescent dyes into the nanoparticles demonstrated their ability to function as nanocarriers.     

Comparison study of the solution phase versus solid phase place exchange reactions in the controlled functionalization of gold nanoparticles

Gold nanoparticles offer tremendous potential in the areas of nanoelectronics, bio- and chemosensors, and catalysis. However, before these applications are realized, the surface functionality of nanoparticles must be better controlled. Our lab has recently reported a novel synthetic approach for making monofunctionalized nanoparticles through a solid phase place exchange reaction. Monofunctionalized gold nanoparticles may also be prepared through a solution phase place exchange reaction. In this study, we compared the efficiency of these two separate approaches toward controlled functionalization of gold nanoparticles by (1)H NMR, Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) analysis. We found that the solid phase place exchange approach is much more efficient at producing monofunctionalized gold nanoparticles. (1)H NMR data were used to give a semiquantitative count of substituted bifunctional ligands, and FT-IR spectra supported these findings. Furthermore, we used a diamine coupling reaction of nanoparticles to show the presence of single or multiple functional groups on the nanoparticle surface by TEM analysis.     

One-pot synthesis,characterization, and drug loading of polysaccharide-based nanoparticles with carboxy functional groups

Herein, various polysaccharide-based nanoparticles were synthesized from dextran, hydroxypropyl cellulose, and hydroxyethyl cellulose, respectively, by a self-assembly assisted approach. This approach enables us to prepare stable polysaccharide-based nanoparticles with carboxy functional groups directly from monomers without using any surfactant and organic solvent. The existence of abundant carboxyls in these polysaccharide-based nanoparticles provides them obvious pH sensitivity as verified by ¹H nuclear magnetic resonance as well as the potential in loading cationic drug.     

Rapid synthesis of stable and functional conjugates of DNA/gold nanoparticles mediated by Tween 80

Gold nanoparticles conjugated with DNA represent an attractive and alternative platform for broad applications in biosensors, medical diagnostic, and biological analysis. However, current methods to conjugate DNA to gold nanoparticles are time-consuming. In this study, we report a novel approach to rapidly conjugate DNA to gold nanoparticles (AuNPs) to form functional DNA/AuNPs in 2-3 h using Tween 80 as protective agent. With a fluorescence-based technique, we determine that the DNA density on the surface of AuNPs achieves about ～60 strands per particles, which is comparable to the loading density in the current methods. Moreover, the DNA/AuNPs synthesized by our approach exhibit an excellent stability as a function of temperature, pH, and freeze-thaw cycle, and the functionality of DNA/AuNPs conjugates is also verified. The work presented here has important implications to develop the fast and reproducible synthesis of stable DNA-functionalized gold nanoparticles.     

Bioinspired and green synthesis of nanoparticles from plant extracts with antiviral and antimicrobial properties: A critical review

Currently green synthesis of nanoparticles has attained much interest because of their safe nature, environmentally benign, ease in manufacturing, and low production cost. It is a reliable process for developing a wide array of nanostructures such as metal salts from plants/fungal/bacterial extract and hybrid materials. Green synthesis of nanoparticles provided promising and sustainable alternative approach to conventional synthesis approaches. Recent studies demonstrated that nanoparticles are highly promising for antiviral and antimicrobial properties. Here in, the advancement in green synthesis of nanoparticles using natural compounds such as plant extracts, fruit juices and other relevant sources have been highlighted. A deep insight into antiviral and antimicrobial activities of these nanoparticles provided. These nanoparticles offer diverse opportunity to counter life threating viral and other antimicrobial infections. This review offers understanding of the recent data that provide the readers various strategies to design and develop advance nanomaterials via greener approach. Current challenges, critical overview and future outlook of the green synthesis of nanoparticles and possibilities of their effective and exotic exploration for antimicrobial and antiviral applications are summarized.     

Far-infrared characteristics of ZnS nanoparticles measured by terahertz time-domain spectroscopy

The optical and dielectric properties of ZnS nanoparticles are studied by use of terahertz time-domain spectroscopy (THz-TDS) over the frequency range from 0.3 to 3.0 THz. The effective medium approach combined with the pseudo-harmonic model of the dielectric response, where nanoparticles are embedded in the host medium, provides a good fit on the experimental results. The extrapolation of the measured data indicates that the absorption is dominated by the transverse optical mode localized at 11.6+/-0.2 THz. Meanwhile, the low-frequency phonon resonance of ZnS nanoparticles is compared with the single-crystal ZnS. The THz-TDS clearly reveals the remarkable distinction in the low-frequency phonon resonances between ZnS nanoparticles and single-crystal ZnS. The results demonstrate that the acoustic phonons become confined in small-size nanoparticles.