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Gold nanoparticles were synthesized using brown seaweed ( Sargassum crassifolium ) extract and chloroauric acid solution. This is an easy, cheap and environment friendly synthesis method for the formation of gold nanoparticles. The gold nanoparticles with varying amount of seaweed extract was characterized using Ultraviolet-visible spectroscopy. Moreover, Transmission Electron Microscopy characterization was used to observe the shape and size of gold nanoparticles. Experimental results revealed that varying the amount of brown seaweed extract can control the optical absorption spectra of the produced gold nanoparticles. Greater amount of brown seaweed extract will exhibit peak in the lower wavelength while smaller amount of seaweed extract will exhibit peak in the higher wavelength. It is believed that the wavelength of free surface electrons resonance is related to the shift of absorption peak. TEM images revealed a more spherical and smaller particles as the amount of brown seaweed extract was increased. This simple green synthesis method of gold nanoparticles will give a cost effective route in the mass production of gold nanoparticles for biomedical applications.
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Controlling the Absorption Spectra of Gold
Nanoparticles Synthesized via Green Synthesis
Using Brown Seaweed (Sargassum crassifolium) Extract
Johnny Jim S. Ouano1,3,a, Mar Christian O. Que4,d, Blessie A. Basilia4,c
and Arnold C. Alguno2,b
1Materials Science Laboratory, Department of Physics
2Primier Reseach Institute of Science and Mathematics (PRISM), Mindanao State University
Iligan Institute of Technology, A Bonifacio Avenue, Iligan City, 9200, Philippines
3Physics Department, Mindanao State University, Marawi City, 9700, Philippines
4Department of Science and Technology, Industrial Technology Development Institute Bicutan,
Taguig City, 1631, Philippines,,,
Keywords: gold nanoparticle, green synthesis, UV-Vis spectroscopy, Transmission electron
Abstract. Gold nanoparticles were synthesized using brown seaweed (Sargassum crassifolium)
extract and chloroauric acid solution. This is an easy, cheap and environment friendly synthesis
method for the formation of gold nanoparticles. The gold nanoparticles with varying amount of
seaweed extract was characterized using Ultraviolet-visible spectroscopy. Moreover, Transmission
Electron Microscopy characterization was used to observe the shape and size of gold nanoparticles.
Experimental results revealed that varying the amount of brown seaweed extract can control the
optical absorption spectra of the produced gold nanoparticles. Greater amount of brown seaweed
extract will exhibit peak in the lower wavelength while smaller amount of seaweed extract will
exhibit peak in the higher wavelength. It is believed that the wavelength of free surface electrons
resonance is related to the shift of absorption peak. TEM images revealed a more spherical and
smaller particles as the amount of brown seaweed extract was increased. This simple green
synthesis method of gold nanoparticles will give a cost effective route in the mass production of
gold nanoparticles for biomedical applications.
Synthesis of gold nanoparticles (GNPs) are being studied rigorously because of its various
applications in biomedical field including drug delivery [1], cancer photodiagnostics and
phototherapy [2]. Likewise it has been reported that GNPs are being utilized as antibacterial [3] and
anticancer [4] agents. In addition, gold nanoparticles can be used in industrial applications as
coatings and printings [5] and as building blocks in nanoelectronics [6]
Several methods has been developed in synthesizing gold nanoparticles. Such are chemical,
physical and biological methods. These methods aim to reduce HAuCl4 (Chloroauric acid) by
addition of organic or inorganic reducing agents. It was reported that physical method utilize
irradiation technique to enhance the synthesis process of gold nanoparticles. However this method
is quite expensive and sophisticated. On the other hand, chemical synthesis utilizes inorganic agents
and shows an effective reduction process that produces a monodispersed particles [7]. However,
there is an issue of toxicity in the process [8]. To address this problem, green synthesis route can be
a good alternative utilizing biological agents. It offers a straight forward and environment friendly
process [9]. Previous works utilized biological agents like plant extract [10], bacteria [11] and fungi
[12] as reductants and capping agents of gold nanoparticles. In like manner, it was reported that
microbe mediated synthesis is not good for industrial applications due to contamination and
Key Engineering Materials Submitted: 2018-04-12
ISSN: 1662-9795, Vol. 772, pp 78-82 Accepted: 2018-04-25
doi:10.4028/ Online: 2018-07-04
© 2018 Trans Tech Publications, Switzerland
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans
Tech Publications, (#108921510-12/07/18,08:55:06)
maintenance issues [13]. It has been reported that plant extracts contain biomolecules such as
terpenoids, flavones, ketones, aldehydes, amides and carboxylic acids [14]. These biomolecules
may act as reduction and capping agent in the synthesis of GNP’s. On the other hand, marine algae
was also used to synthesize GNPs because it is rich in biological compounds [15]. Specifically,
brown seaweeds were used to synthesize gold nanoparticles [16]. However, they were not able to
control the absorption spectra of the synthesized GNPs. Moreover, they failed to correlate the
absorption spectra with respect to size, shape and density of the synthesized GNPs.
In this work, we are going to control the absorption spectra of the synthesized GNP by
controlling the amount of seaweed extract. The size, shape and density of the synthesized GNPs
will be intensively elucidated using Transmission electon microscopy and associate its structural
morphology to its absosrption spectra.
Materials and Methods
Brown seaweeds (Sargassum crassifolium) were collected from the seashore of Biga, Lugait,
Misamis Oriental in the Philippines. The seaweeds were washed with fresh water with final
washing of distilled water. It was then air dried for 5 days then oven dried for 24 hours at 60o C.
The dried seaweeds were pulverized using an analytical mill then sieve thru a 0.5 mm strainer. Fifty
grams of fine grain biomass was added to 500 ml deionized water and was stirred to disperse the
powder. The mixture was set aside for 24 hours before it was filtered. The seaweed broth was kept
in refrigerator at 4o C for future use. Preparation of 1 milli molar (mM) Chloroauric acid was done
by mixing 1470 ml of deionized water and 0.5 grams of Gold chloride hydrate (from Aldrich Sigma
with 99.995% trace metal base). The synthesis of GNPs was done by preparing four vials filled with
20 ml of 1 mM cloroauric acid then 10 ml, 12 ml, 14 ml and 16 ml of the seaweed extracts were
added to each vial respectively. The reactants were shaked until the color changes from brown to
purple and were set aside for 24 hours to complete the reaction process. Samples in cuvettes were
characterized using Perkin Elmer Lambda 35 UV-Vis Spectrometer in order to measure the
absorption spectra of synthesized GNPs and to observe the effect of the variation of the seaweed
extract. On the other hand, Transmission Electron Microscopy (TEM) measurement was also
performed using JEOL JEM-2100F to observe the size, shape of GNPs and the changes in its
morphology due to variation of seaweed extracts. In addition, the selected area of electron
diffraction (SAED) was also performed in the TEM to observe the crystallinity of the synthesized
gold nanoparticles.
Results and Discussion
Fig. 1. UV-vis spectra of gold nanoparticles showing an increase in absorbance and decrease in wavelength
peak when the amount of seaweed (Sargassum crassifolium) extract was increased.
Key Engineering Materials Vol. 772 79
The UV-Vis spectra shown in Fig. 1 revealed that the peaks of the absorption spectra shifted to
lower wavelength as the amount of seaweed extract was increased. It has been reported that the
wavelength of free surface electron resonance of GNPs is related to the absorption peaks. UV-Vis
spectra revealed that blue shifts of absorption peaks occurred when the amount of seaweed extract
was increased. This blue shifts of absorption peaks of synthesized GNPs can be associated to the
increase of the amount of seaweed extract and probably triggered by smaller sizes of GNPs. The
absorption peak was maintained at 536 nm for 14 ml and 16 ml of seaweed extract maybe because
the biomolecules cease to act as reducing and capping agent of GNPs.
The TEM images of the synthesized GNPs with varied amount of seaweed extract is shown in
Fig. 2. It is very apparent that polydisperse GNPs are present. Sizes of GNPs approximately ranges
from 25 nm to 200 nm in various shapes such as triangles, pentagons, hexagons and colloids.
Moreover, the distribution is nearly monodisperse and spherical in shape as the amount of seaweed
extract was increased. These various formations of GNP’s might be triggered by the presence of
different biomolecules in the seaweed extracts. In fact, it was reported that seaweed extracts contain
sulphated polysaccharides and monosaccharide groups, polyphenol, sodium-aliginate and secondary
metabolite such as flavonoids, tannins, phenolics, sterols and terpenoids that maybe serve as
nucleation centers to commence the formation of GNP’s[17]. These biological compounds present
in seaweed extract might be responsible for the reduction and capping of the synthesized GNPs.
Fig. 2. TEM image of GNPs with varied seaweed extracts (a) 10 ml, (b) 12 ml, (c) 14 ml and (d) 16 ml.
80 Composite Materials Science and Technology
The crystallinity of the synthesized GNPs are shown in Fig 3 in which the fringe spacing is ~
0.17016 nm (a) which corresponds to the spacing of (111) plane of the face centered cubic GNPs.
The typical Selected area electron diffraction (SAED) patterns (b) with bright circular rings may
correspond to the (111), (200), (220), (311) and (222) planes showed the high crystallinity of GNPs.
Fig. 3. (a) Fringe spacing of (111) plane and (b) SAED ring patterns of GNPs.
The absorption spectra of gold nanoparticles synthesize via green synthesis route using
Sargassum crassifolium extract can be controlled by controlling the amount of seaweed extract.
This change in absorption spectra of GNPs may be attributed to the change in morphological
structure of GNPs resulting in the change of resonance wavelength of GNPs. This easy and cost
effective synthesis process may be utilized in the mass production of gold nanoparticles for
industrial and medical applications.
DOST-PCIEERD is acknowledged for the equipment grant. Dr. Drexel Camacho is also
acknowledged for scientific discussions.
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... 1470 ml of distilled water and 0.5 g of gold chloride hydrate were combined to make 1 mM chloroauric acid. To finish the reaction, the reactants were shaken until the color changed from brown to purple, then put aside for 24 h (Ouano et al., 2018). Similar reports have been reported on the synthesis of AuNPs from the alga Tetraselmis kochinensis (Senapati et al., 2012). ...
In the recent two decades, there has been a tremendous increase in the biosynthesis of nanomaterials employing live organisms, their components, extracts, or biomolecules as catalysts. Algae has been used majorly for commercial and industrial uses such as food, feed, skin care, medicines, and fertilizers, algae are now being explored to synthesize green nanoparticles (NPs). Indeed, algae are a rich source of bioactive substances, are easy to produce, grow quickly, and are scalable, therefore this trend is growing by the day. The natural material from algae works as a capping and stabilizing factor in the conversion of metal compounds to metal, metal oxides, or bimetallic NPs. The NPs generated by algae might be intracellular or extracellular, depending on the area of the NPs. The aim of the present review, the first of its kind, is to provide readers with essential information about the diversity of algal strains exploited in the booming field of nanobiotechnology and to explore the biomedical applications of NPs biosynthesized from algae which include antimicrobial, antioxidant, anticancer and biocompatibility properties. Furthermore, this study examines the rationale for the algal-mediated creation of metal, metal oxide, and bimetallic NPs from a variety of algae, as well as the characterization of algae-mediated nanomaterial synthesis.
... According to Ponnuchamy and Jacob (2016), compared to other species of macroalgae, brown macroalgae have been exploited more in the synthesis of MNPs since the cell wall of their cells contains a variety of mucilaginous polysaccharides and functional groups that aid in the absorption of metals. It has already been shown, for example, that the synthesis of AuNPs from marine brown macroalgae Sargassum muticum (Namvar et al., 2015), S. polycystin (Sivaraj et al., 2015), S. crassifolium (Ouano et al., 2018), S. cichorioides (González-Ballesteros et al., 2021), Turbinariaornata (Deepak et al., 2018) and Padina tetrastromatica (Princy& Gopinath, 2018;Kumar et al., 2021) provide fruitful alternatives to chemical methods conventional. Other macro-and microalgae species already used in the synthesis of AuNPs include Stoechospermum marginatum, S. myriocystum, Turbinaria conoides, T. ornata, Spirulina platensis, Corallina officinalis, Cladosiphonokamuranus, Laminaria japonica, Ecklonia cava, Gracilaria verrucose, among others [see Roy et al. (2013) and references therein]. ...
The use of vegetal species for gold nanoparticles (AuNPs) biosynthesis can constitute an alternative to replacing the extensive use of several hazardous chemicals commonly used during NPs synthesis and, therefore, can reduce biological impacts induced by the release of these products into the natural environment. However, the “green nanoparticles” and/or “eco-friend nanoparticles” label does not ensure that biosynthesized NPs are harmless to non-target organisms. Thus, we aimed to synthesize AuNPs from seaweed Gracilaria crassa aqueous extract through an eco-friendly, fast, one-pot synthetic route. The formation of spherical, stable, polycrystalline NPs with a diameter of 32.0 nm ± 4.0 nm (media ±SEM) was demonstrated by UV–vis spectroscopy, field emission scanning electron microscopy, and high-resolution transmission electron microscopy, energy-dispersive X-ray and X-ray diffraction measurement, and Fourier-transform infrared spectroscopy analysis. In addition, different phytocomponents were identified in the biosynthesized AuNPs, using Gas Chromatography-Mass Spectrometry (GC-MS). However, both G. crassa aqueous extract and the biosynthesized AuNPs showed high ecotoxicity in Anopheles stephensi larvae exposed to different concentrations. Therefore, our study supports the potential of seaweed G. crassa as a raw material source for AuNPs biosynthesis while also shedding light on its ecotoxicological potential, which necessitates consideration of its risk to aquatic biota.
... The diameter of the particles obtained under such conditions was somewhat smaller and amounted to 6 nm for the medium after the growth of D. salina and, after A. thaliana, 15 nm. Consequently, there is no doubt that extracellular metabolites of plants are capable of reducing gold salts with the formation of GNPs [37]. The question remains whether the synthesis of GNPs is intracellular. ...
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The ability of the suspension culture of Arabidopsis thaliana cells and Dunaliella salina microalga to reduce gold ions with the formation of nanoparticles is shown. The average diameter of gold nanoparticles obtained using D. salina for synthesis appeared to be less than when using A. thaliana cells: 8 and 25 nm, respectively. Freshly prepared culture media used for growing cells of both dunaliella and arabidopsis did not reduce gold salts with the formation of nanoparticles. After the cells were grown and freed by centrifugation and/or filtration, culture media turned out to be capable of gold reduction.
... There are few reports of the synthesis of gold nanoparticles using extracts of natural products as, fungi [11,12] bark of Mimusops elengi [13], Couroupita guianensis [14], husk of citrus maxima [15], fruit extract of Genipa americana [16], Ly- cium chinense [17], dragon [18], vegetable waste [19], fruit juice of Lognam [20], Moringa olifera [21], Actinidia deliciosa [22], Brassica oleracea [23], Magnusiomyces ingens LH-F1 [24]. Algae were recently known as a bionanofactories, since these were used for the synthesis of nanoparticles in different way, for example gold nanoparticles were synthesized using the extract of sea weed such a Sargassam [25][26][27], Turbinaria [28], Corallina [29], Stoechospermum [30], Cystoceria buccata [31], green algae Chlorella vulgaris [32], Chlorella pyrenoidusa [33], Pithophora oedogonia [34], Ulva fasciata [35], and cyanobacteria Received 21 December 2018; Received in revised form 20 February 2019;Accepted 22 February 2019 Spirulina platensis [36], Plectonema boryanum [37], Calothrix spp [38], Phormidium valderianum [39]. ...
... There are few reports of the synthesis of gold nanoparticles using extracts of natural products as, fungi [11,12] bark of Mimusops elengi [13], Couroupita guianensis [14], husk of citrus maxima [15], fruit extract of Genipa americana [16], Lycium chinense [17], dragon [18], vegetable waste [19], fruit juice of Lognam [20], Moringa olifera [21], Actinidia deliciosa [22], Brassica oleracea [23], Magnusiomyces ingens LH-F1 [24]. Algae were recently known as a bionanofactories, since these were used for the synthesis of nanoparticles in different way, for example gold nanoparticles were synthesized using the extract of sea weed such a Sargassam [25][26][27], Turbinaria [28], Corallina [29], Stoechospermum [30], Cystoceria buccata [31], green algae Chlorella vulgaris [32], Chlorella pyrenoidusa [33], Pithophora oedogonia [34], Ulva fasciata [35] Spirulina platensis [36], Plectonema boryanum [37], Calothrix spp [38], Phormidium valderianum [39]. In addition to this Khan et al. [35] extensively reviewed the recent progress of algae and blue-green algaeassisted synthesis of gold nanoparticles for various applications. ...
An ecofriendly and efficient method (photoinduced) has been used for green synthesis of stable gold nanoparticles (AuNPs) using aqueous extract as a reducing and stabilizing agent, derived from halotolerant microalga Dunaliella salina. Synthesis of AuNPs was confirmed by UV–Vis spectroscopy showing sharp SPR band at 560 nm after 30 min exposure of sunlight. The synthesis was optimized further as exposure(75min) to sunlight, aqueous extract of Dunaliella (AED) inoculum dose(30%) and HAuCl 4 .xH 2 O (1 mM). The presence of nearly spherical shape of AuNPs with average size of 22.4 nm and crystalline nature were confirmed by TEM, SAED and XRD analysis. The XPS analysis of AuNPs showed presence of two individual peaks at 85.17 and 88.94eV that attributed to Au 4f7/2 and Au 4f5/2 respectively. Phycochemical analysis of AED demonstrated presence of phenolics, flavonoids, tannin and proteins. AED when subjected to SDS-PAGE showed protein bands of 92 and 66 KDa. AuNPs were tested for anticancer activity on MCF7 (cancer) and MCF 10A (normal) cell lines, keeping commercial drug cisplatin as positive control. AuNPs selectively killed cancer cells and were not detrimental to the normal cell line whereas cisplatin killed normal cells also at 48 h exposure, therefore, such AuNPs may be used as an anticancer agent.
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Metallic nanoparticles are being utilized in every phase of science along with engineering including medical fields and is still charming scientists to explore new dimensions for their respective worth which is generally attributed to their corresponding small sizes. The up-andcoming researches have proven their antimicrobial significance. Among several noble metal nanoparticles, silver nanoparticles have attained a special focus. Conventionally silver nanoparticles are synthesized by chemical method using chemicals as reducing agents which later on become accountable for various biological risks due to their general toxicity; engendering the serious concern to develop environment friendly processes. Thus, to solve the objective; biological approaches are coming up to fill the void; for instance green syntheses using biological molecules derived from plant sources in the form of extracts exhibiting superiority over chemical and/ or biological methods. These plant based biological molecules undergo highly controlled assembly for making them suitable for the metal nanoparticle syntheses. The present review explores the huge plant diversity to be utilized towards rapid and single step protocol preparatory method with green principles over the conventional ones and describe the antimicrobial activities of silver nanoparticles.
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Spherical gold nanoparticles (Au) were chemically prepared and characterized by transmission electron microscope (TEM) and UV spectra. Their antimicrobial activities against major foodborne pathogens were studied. Antimicrobial activities of Au nanoparticles had been increased with their higher volume. Best antifungal activity was observed on using fluconazole coated with 40 µl Au nanoparticles with zone of inhibition 14mm against A. niger, 13mm C. albicans and 12mm A. flavus. Minimum inhibitory concentration test (MIC) revealed synergistic effect of Au nanoparticles with ciprofloxacin when compared with ciprofloxacin alone. Best results were shown against S. Typhimurium (0.097, 0.19), B. cereus (0.19, 0.39), E.coli O157 (0.39, 0.39), P. aeruginosa and L. monocytogenes (0.39, 0.78) and finally S. aureus (0.78, 6.25) respectively. Gold nanoparticles and fluconazole coated with Au nanoparticles showed variable MIC against C. albicans, A. niger (6.25, 3.125) and A. flavus (12.5, 6.25), respectively. TEM revealed small size of gold nanoparticles (range 9-19 nm) trapped by the biofilm released by S. Typhimurium and easily attached to the surface of cell membrane which drastically disturbed its proper function like respiration and permeability. Interaction between S. Typhimurium and ciprofloxacin coated with gold nanoparticles revealed that the cell wall was loosened and separated from the membrane or disrupted with complete absence of flagella. TEM of S. Typhimurium using ciprofloxacin alone showed intact bacterial cell wall with the accumulation of antibiotic on the cell wall and partial destruction of flagella. Drugs capped gold particle act as a single group against the microorganism which was indicated by using disk diffusion method with increase zone of inhibition of Au alone, ciprofloxacin alone and Au coated ciprofloxacin from 12, 26 and 30 mm, respectively. Also, it was clarified by the decrease in MIC from 6.25, 0.19 to 0.097, respectively. Results indicated that drugs coated with nanoparticles were highly effective against tested isolates so that Au nanoparticles can minimize treatment durations and side effects of drugs. [M. F. Zawrah and Sherein I. Abd El-Moez Antimicrobial Activities of Gold Nanoparticles against Major Foodborne Pathogens] Life Science Journal. 2011;8(4):37-44] (ISSN:1097-8135). Introduction Nanotechnology offers unique approaches to control a wide variety of biological and medical processes that occur at nanometer length and it is believed to have a successful impact on biology and medicine (West and Halas 2000; Zandonella, 2003). By controlling the structure precisely at nano scale dimensions, one can control and modify their surface layer for enhanced aqueous solubility, biocompatibility or bio-conjugation. Nanoparticles exhibit attractive properties like high stability and the ability to modify their surface characteristics easily. The basic necessities for drug targeting are that the carrier should be capable of extended circulation in the blood stream; it must be small enough to gain access to target tissues and target cells (Tom et al. 2004). Nowadays, research efforts are being concentrated on integrating nanoparticles with biology. It has been reported that antibiotics often disturb the bacterial flora of digestive tract which may develop multiple drug-resistant isolates, hence novel ways of formulating biocide materials is an upcoming field of attraction (Jarvinen et al. 1993; Concannon et al. 2003; Altman et al. 2006; Daglia et al. 2007). For this reason, there is a need for the use of an agent which does not generate resistance and presents a good bactericidal property. Gold nanoparticles have a great bactericidal effect on a several range of microorganisms; its bactericidal effect depends on the size and the shape of the particle (Nirmala and Pandian, 2007). Nanoparticles can act as antibacterial and antifungal agents, due to their ability to interact with microorganisms (Hernandez et al. 2008; Dror-Ehre et al. 2009; Eby et al. 2009; Panacek et al. 2009). Exerting their antibacterial properties, nanoparticles attach to the surface of the cell. This interaction causes structural changes and damage, markedly disturbing vital cell functions, such as permeability, causing pits and gaps, depressing the activity of respiratory chain enzymes, and finally leading to cell death (Rai et al. 2009; Sharma et al. 2009; Li et al. 2010). In vitro antibacterial activities
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Objective: To analyse qualitative and quantitative phytochemical and evaluate in vitro antioxidant properties of various alcoholic and aqueous extracts of leaf and root parts of Hypochaeris radicata. Methods: Preliminary phytochemical analysis for alkaloids, cardiac glycosides, flavonoids, glycosides, phenols, resins, saponins, steroids, tannins, terpenoids and triterpenoids and quantitative phytochemical analysis for alkaloids, total phenolics, total flavonoids, tannins, saponins and ascorbic acid were made by following standard procedures. In vitro antioxidant properties were evaluated by assessing DPPH(•), NO(•) and ABTS(•+), radical scavenging abilities and assaying the reducing power, β-carotene and antihemolytic activities by adapting standard methods. Results: The quantitative phytochemical analysis of this species exhibited the presence of alkaloids, total phenolics, total flavonoids, tannins, saponins and ascorbic acid in considerable quantity. The in vitro antioxidant activity of the species, Hypochaeris radicata clearly demonstrated that both the leaf and root parts have prominent antioxidant properties. Conclusions: From this study, it can be concluded that the species is effective in scavenging free radicals and has the potential to be a powerful antioxidant.
Conference Paper
The nanotechnology and biomedical sciences opens the possibility for a wide variety of biological research topics and medical uses at the molecular and cellular level. The biosynthesis of nanoparticles has been proposed as a cost-effective and environmentally friendly alternative to chemical and physical methods. Plant-mediated synthesis of nanoparticles is a green chemistry approach that connects nanotechnology with plants. Novel methods of ideally synthesizing NPs are thus thought that are formed at ambient temperatures, neutral pH, low costs and environmentally friendly fashion. Keeping these goals in view nanomaterials have been synthesized using various routes. Among the biological alternatives, plants and plant extracts seem to be the best option. Plants are nature’s “chemical factories”. They are cost efficient and require low maintenance. The advantages and disadvantages of nanotechnology can be easily enumerated. This study attempts to review the diversity of the field, starting with the history of nanotechnology, the properties of the nanoparticle, various strategies of synthesis, the many advantages and disadvantages of different methods and its application.
The effective coupling of optical surface plasmons (SPs) and electron transport in a plasmonic-electronic device is one of the fundamental issues in nanoelectronics and the emerging field of plasmonics, and offer promise in providing a solution to next generation nanocircuits in which all coupling is in the near field. Attempts toward this end, however, are limited because of the integration challenge to compatible nanodevices. To date, direct electrical detection of SP-electron coupling from metallic nanostructures alone are not reported, thus it remains a great experimental challenge. In this paper, we succeed in preparing a new suspended-film-type nanoelectronic junction, in which free-standing 2D fractal nanoparticle networks act as plasmonically active nanocomponents. Direct electrical detection of optical collective SPs was evidenced by photo-current response of the junction upon illumination. Room-temperature I-V characteristics, differing from nonlinear to Ohmic behaviors, are found sensitive to the nm-scale morphology changes of the nano-membranes. The finding and approach may enable the development of advanced plasmonic nanocircuits and new nanoelectronics, nanophotonics, and (solar) energy applications.
Nanotechnology is a field that is mushrooming, making an impact in all spheres of human life. Nanobiotechnology represents an economic alternative for chemical and physical methods of nanoparticles formation. Presently available literature revealed that the NP synthesis using marine plants, microrganisms and algae as source has been unexplored and underexploited. The development of green processes for the synthesis of NP is evolving into an important branch of nanotechnology. It has many advantages such as, ease with which the process can be scaled up, economic viability, etc. Presently, the researchers are looking into the development of cost-effective procedures for producing reproducible, stable and biocompatible AgNPs and AuNPs. Antibiotic resistance is the world's major public healthcare problem. AgNPs and AuNPs particles play a vital role in nanobiotechnology as biomedicine against Drug-resistant bacteria.