INTRODUCTION:

Nanotechnology can be termed as the synthesis, characterization, exploration and application of nano sized (1-100nm) materials for the development of science. It deals with the materials whose structures exhibit significantly novel and improved physical, chemical, and biological properties, phenomena, and functionality due to their nano scaled size. Because of their size, nanoparticles have a larger surface area than macro-sized materials.

Argent nanoparticles are one of the promising products in the nanotechnology industry. The development of consistent processes for the synthesis of argent nanomaterials is an important aspect of current nanotechnology research [1].

The argent nanoparticles can be synthesized by the other three methods physical, chemical and biological methods. The field of nanotechnology is one of the most active research areas in modern material science. Argent nanoparticles have found application in different areas, including medicine catalysis biotechnology and water treatment etc. Argent nanoparticles have already been used tested in various field of biological science like drug delivery, water treatment, and antibacterial compound against both gram positive and gram negative bacteria by various researches [2].

MATERIALS AND METHODS:

Argent Nanoparticles prepared by three methods

1) Physical Method

2) Chemical Method

3) Biological Method

Synthesis of AgNPs Using Physical and Chemical Methods:

Generally, the synthesis of nanoparticles has been carried out using three different approaches, including physical, chemical, and biological methods. In physical methods, nanoparticles are prepared by evaporation-condensation using a tube furnace at atmospheric pressure. Conventional physical methods including spark discharging and pyrolysis were used for the synthesis of AgNPs. The advantages of physical methods are speed, radiation used as reducing agents, and no hazardous chemicals involved, but the downsides are low yield and high energy consumption, solvent contamination, and lack of uniform distribution [3].

Chemical methods use water or organic solvents to prepare the silver nanoparticles .This process usually employs three main components, such as metal precursors, reducing agents, and stabilizing/capping agents. Basically, the reduction of silver salts involves two stages (1) nucleation; and (2) subsequent growth. In general, silver nanomaterials can be obtained by two methods, classified as “top-down” and “bottom-up. The “top-down” method is the mechanical grinding of bulk metals with subsequent stabilization using colloidal protecting agents. The “bottom-up” methods include chemical reduction, electrochemical methods, and sono-decomposition. The major advantage of chemical methods is high yield, contrary to physical methods, which have low yield. The above-mentioned methods are extremely expensive. Additionally, the materials used for AgNPs synthesis, such as citrate, borohydride, thio-glycerol, and 2-mercaptoethanol are toxic and hazardous. Apart from these disadvantages, the manufactured particles are not of expected purity, as their surfaces were found to be sedimented with chemicals. It is also very difficult to prepare AgNPs with a well-defined size, requiring a further step for the prevention of particle aggregation [4].

In addition, during the synthesis process, too many toxic and hazardous byproducts are excised out. Chemical methods make use of techniques such as cryo chemical synthesis, laser ablation, lithography, electrochemical reduction, laser irradiation, sono-decomposition, thermal decomposition, and chemical reduction. The advantage of the chemical synthesis of nanoparticles are the ease of production, low cost, and high yield; however, the use of chemical reducing agents are harmful to living organisms. Recently, Abbasi et al. explained a detailed account of synthesis methods, properties, and bio-application of AgNPs [5].

METHOD OF CHARACTERIZATION:

U.V-VIS Spectroscopy:

UV-VIS spectroscopy is a very useful and reliable technique for the primary characterization of synthesized nanoparticles which is also used to monitor the synthesis and stability of AgNPs. AgNPs have unique optical properties which make them strongly interact with specific wavelengths of light. In addition, UV-vis spectroscopy is fast, easy, simple, sensitive, selective for different types of NPs, needs only a short period time for measurement, and finally a calibration is not required for particle characterization of colloidal suspensions. In AgNPs, the conduction band and valence band lie very close to each other in which electrons move freely. These free electrons give rise to a surface plasmon resonance (SPR) absorption band, occurring due to the collective oscillation of electrons of silver nano particles in resonance with the light wave. The absorption of AgNPs depends on the particle size, dielectric medium, and chemical surroundings. Observation of this peak—assigned to a surface plasmon—is well documented for various metal nanoparticles with sizes ranging from 2 to 100 nm. The stability of AgNPs prepared from biological methods was observed for more than 12 months, and an SPR peak at the same wavelength using UV-VIS spectroscopy was observed [6].

Zeta potential:

Surface zeta potential were measured using the laser zeta meter (Malvern zeta seizer 2000, Malvern). Liquid samples of the nanoparticles (5ml) were diluted with double distilled water (50ml). The pH was adjusted to the required value. The sample were shaken for 30 min. After shaking, the equilibrium PH was recorded and the zeta potential of the argent particles was measured. A zeta potential was used to determine the surface potential of the argentum nanoparticles. In each case, an average of three separate measurements was reported. Zeta values were measured and found to fall between −25.5 and −38.3 mV. These values provide full stabilization of the nanoparticles at different pH [7].

Scanning electron microscopy:

The SEM image of argent nanoparticles synthesized by microbial, chemical reduction and argent bio nanocomposites. It gave a clear image of highly dense argent nano particles. The SEM image showing argent nanoparticles synthesized confirmed the development of argent nanostructures [8].

X-ray Diffraction (XRD):

X-ray diffraction (XRD) is a popular analytical technique which has been used for the analysis of both molecular and crystal structures, qualitative identification of various compounds quantitative resolution of chemical species, measuring the degree of crystallinity, isomorphous substitutions, particle sizes, etc. When X-ray light reflects on any crystal, it leads to the formation of many diffraction patterns, and the patterns reflect the physico-chemical characteristics of the crystal structures. In a powder specimen, diffracted beams typically come from the sample and reflect its structural physico-chemical features. Thus, XRD can analyze the structural features of a wide range of materials, such as inorganic catalysts, superconductors, biomolecules, glasses, polymers, and so on . Analysis of these materials largely depends on the formation of diffraction patterns. Each material has a unique diffraction beam which can define and identify it by comparing the diffracted beams with the reference database in the Joint Committee on Powder Diffraction Standards (JCPDS) library. The diffracted patterns also explain whether the sample materials are pure or contain impurities. Therefore, XRD has long been used to define and identify both bulk and nanomaterials, forensic specimens, industrial, and geochemical sample materials. XRD is a primary technique for the identification of the crystalline nature at the atomic scale [9].

Dynamic Light Scattering:

Physicochemical characterization of prepared nanomaterials is an important factor for the analysis of biological activities using radiation scattering techniques. DLS can probe the sizedistribution of small particles a scale ranging from submicron down to one nanometer in solution or suspension. Dynamic light scattering is a method that depends on the interaction of light with particles. This method can be used for the measurement of narrow particle size distributions, especially in the range of 2–500 nm Among the techniques for the characterization of nanoparticles, the most commonly used is DLS . DLS measures the light scattered from a laser that passes through a colloid, and mostly relies on Rayleigh scattering from the suspended nanoparticle [10].

X-ray Photoelectron Spectroscopy (XPS):

XPS is a quantitative spectroscopic surface chemical analysis technique used to estimate empirical formula. XPS is also known as electron spectroscopy for chemical analysis (ESCA).

XPS plays a unique role in giving access to qualitative, quantitative/semi-quantitative, and speciation information concerning the sensor surface. XPS is performed under high vacuum conditions [11].

RESULT AND DISCUSSION:

Argent nanoparticle was synthesized using three method; Physical method, Chemical method and Biological method. In physical methods, nanoparticles are prepared by evaporation-condensation using a tube furnace at atmospheric pressure. Conventional physical method including spark discharging and pyrolysis were used for the synthesis of argent nanoparticles.

In, chemical methods water and organic solvent used to prepare the argent nanoparticles. This process usually employs three main components such as metal precursor, reducing agent, and stabilizing/ capping agents.

Biologically mediated synthesis of nanoparticles have been shown to be simple, cost effective, dependable, and environmentally friendly and much attention has been given to the high yield production of argent nanoparticles of define size using various biological systems including bacteria, fungi etc.

The characterization of argent nanoparticles has been done by using the different methods such as; U V VIS spectroscopy, Zeta potential, Scanning electron microscopy, X-ray diffraction, Dynamic light scattering.

REFERENCE:

1. P.G. Luo and F.j. Sttzenberger, “Nanotechnology in the detection and control of microorganism.” Adv.appl.Microbial. (2008), vol.63, pp. 145-181.

2. Shameli, K.; Ahmad, M.B.; Yunus, W.M.Z.W.; Ibrahim, N.A.; Gharayebi, Y.; Sedaghat, S. Synthesis o silver/montmorillonite nanocomposites using -irradiation. Int. J. Nanomed. 2010, 5, 1067–1077.

3. Wiley B.; Sun, Y.; Mayers, B.; Xia, Y. Shape-controlled synthesis of metal nanostructures: The case of silver. Chemistry 2005, 11, 454–463.

4. Abou El-Nour, K.M.; Eftaiha, A.; Al-Warthan, A.; Ammar, R.A. Synthesis and applications of silver nanoparticles. Arab. J. Chem. 2010, 3, 135–140.

5. Talebi, J.; Halladj, R.; Askari, S. Sonochemical synthesis of silver nanoparticles in Y-zeolite substrate. J.Mater. Sci. 2010, 45, 3318–3324.

6. UV/VIS/IR Spectroscopy Analysis of Nanoparticles, 2012. Available online: http://50.87.149.212/sites/ default/files/nanoComposix%20Guidelines%20for%20UV-vis%20Analysis.pdf (accessed on 5 March 2016)

7. Lin, P.C.; Lin, S.; Wang, P.C.; Sridhar, R. Techniques for physicochemical characterization of nanomaterials. Biotechnol. Adv. 2014, 32, 711–726.

8. Hall, J.B.; Dobrovolskaia, M.A.; Patri, A.K.; McNeil, S.E. Characterization of nanoparticles for therapeutics. Nanomed. Nanotechnol. Biol. Med. 2007, 2, 789–803.

9. Waseda, Y.; Matsubara, E.; Shinoda, K. X-ray Diffraction Crystallography: Introduction, Examples and Solved Problems; Springer Verlag: Berlin, Germany, 2011.

10. Inagaki, S.; Ghirlando, R.; Grisshammer, R. Biophysical characterization of membrane proteins in nanodiscs. Methods 2013, 59, 287–300.

11. Desimoni, E.; Brunetti, B. X-ray photoelectron spectroscopic characterization of chemically modified electrodes used as chemical sensors and biosensors: A review. Chemosensors 2015.

Received on 20.06.2018 Modified on 11.07.2018

Asian J. Research Chem. 2018; 11(5):811-814.

DOI: 10.5958/0974-4150.2018.00143.8