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Controlling the Absorption Spectra of Gold Nanoparticles Synthesized via Green Synthesis Using Brown Seaweed (Sargassum crassifolium) Extract

DOI:10.4028/www.scientific.net/KEM.772.78
Authors:
Johnny Jim Sucgang Ouano at Mindanao State University
Johnny Jim Sucgang Ouano
Mar Christian Que
Mar Christian Que
Blessie Basilia at Industrial Technology Development Institute
Blessie Basilia
Arnold Alguno at Mindanao State University - Iligan Institute of Technology
Arnold Alguno
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Abstract and Figures

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
ajohnnyjim.ouano@g.msuiit.edu.ph, barnold.alguno@g.msuiit.edu.ph, cbasiliablessie@gmail.com,
dmcoque04@gmail.com
Keywords: gold nanoparticle, green synthesis, UV-Vis spectroscopy, Transmission electron
microscopy.
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.
Introduction
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/www.scientific.net/KEM.772.78 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, www.scientific.net. (#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.
Summary
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.
Acknowledgments
DOST-PCIEERD is acknowledged for the equipment grant. Dr. Drexel Camacho is also
acknowledged for scientific discussions.
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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). http://www.lifesciencesite.com. 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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Phytochemical analysis and evaluation of leaf and root parts of the medicinal herb, Hypochaeris radicata L. for in vitro antioxidant activities
Article
Full-text available
  • May 2014
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.
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Green synthesis of nanoparticles: Their advantages and disadvantages
Conference Paper
  • Apr 2016
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.
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Free-Standing Monolayered Metallic Nanoparticle Networks as Building Blocks for Plasmonic Nanoelectronic Junctions
Article
  • Jan 2016
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.
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Review: Green synthesis of silver and gold nanoparticles
Article
  • Jan 2014
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.
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