Formation of Silver Nanoparticles in the root extract of Scutellaria baicalensis and their characterization

This research about on the formation of silver nanoparticles (AgNPs) in extract of Scutellaria Baicalensis roots. Comprehensive analyzes were carried out and the characteristics of these nanoparticles, which can be used in medical practices and environmental cleaning problems. The roots extracts of Scutellaria Baicalensis advocates as reductant and stabilizer. The first proof of the formation of AgNPs is the change of color of solution AgNO3 which was added root extract. Then by UV-Vis spectroscopy identificated the absorption peak of AgNPs at 414nm –461nm interval. Other characterization of AgNPs received with SEM analysis, From SEM pictures it is clear that the AgNPs have a spherical form, with size ranging from 7.12nm to 18.8nm. An average size of AgNPs are 11.35nm. By FTIR analysis of AgNPs was established the structures, the respective bands of the synthesized nanoparticles, and the stretch of bonds.


Introduction
Last years, scientists have tried to create different methods and technologies to get non-toxic forms of nanoparticles. A chemical synthesis of nanoparticles, especially precious metals is widespread. However, since nanoparticles obtained in this way are expensive and toxic, their synthesis in biological methods is of great interest recently. In biosynthesis of nanoparticles no needs applied high pressure and energy, temperature and toxic chemicals. The possible ecofriendly alternatives to chemical and physical methods are biological methods synthesis of nanoparticle using microorganisms [1][2][3] enzymes [4], fungus [5], and plants or plant extracts [6][7][8]. Biological synthesis of nanoparticles using plants extracts in many cases is advantageous than other biological methods which may eliminating the elaborate processes in the technological point of view [9]. The application of nanotechnology in medicine has put this issue more seriously. In this regard, silver nanoparticles having a unique optical and mechanical properties, having antiseptic properties, are of particular importance. There are data that AgNPs with size of 1-4nm can directly pass the cell membrane.Such AgNPs in this dimensions and in spherical form play an important role not only in the medical practice but also in the solution of issues such as treatment problems, as well as diagnostics, and sensors. Therefore the synthesis of AgNPs with this sizes one of the major issues in green synthesis of nanoparticles [10] At present, the size of used nanoparticles as the drug carrier is at least 5-10nm, and there is a need for highly clean, non-toxic nanoparticles to increase the efficacy of the combined drugs. Since silver nanoparticles often paid for this demand, their acquisition became more extensive. The practical properties of AgNPs allow applied them in high contrast imaging method and in detection of human serum antibody [11], for the prevent infection against burn and open wounds by topical ointments [12], membrane transport in native microbial cells [13], enhanced IR absorption spectroscopy [14], mass spectrometry of peptides [15], bio-labeling, optical imaging of cancer [16], biosensors for detection of herbicides [17], and glucose sensor for medical diagnostics [18], colorimetric sensor for histidine [19], determination of "brinogens" in human plasma [20], for measuring ammonia concentration by colorimetric sensors [21]. Besides of above, AgNPs have various important applications: for example, they are using as coatings for solar energy absorption, as an intercalation material for electrical batteries, and as optical receptors for biolabeling [22][23][24].

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Copyrights @ Ahmadov IS. Arch Nano Op Acc J 108 When synthesizing nanoparticles in plant extracts, three different steps can be distinguished [25,26]. In the first step -socalled -induction phase -occurs a rapid metallic ion reduction and seeds metallic nucleation. In second fase small crystals spontaneously aggregate and transform into large aggregates. In the third -termination phase take place the formation of nanoparticles, the sizes and shapes of the nanoparticles become energetically favourable. In this fase specific biomolecules act as capping agents and stabilized the nanoparticles. This process similar to biomineralization, but the nature of formation nanoparticles in the plant extracts is not yet understood in any depth. [27].
In this work was used plant, well-known in medical practize -Scutellaria baicalensis for the synthesis of AgNPs. Root and leafs of Scutellaria baicalensis have many powerful antioxidants. These antioxidants may take play as reductant during reduction of silver ions into nanoparticles. In addition, the molecules of these antioxidants can be adsorbed or even attached to the surface of the nanoparticles during their formation. Such nanochastists can act as nano drugs. The specific antioxidants on the surface of AgNPs makes possible the future use of AgNPs as a nano-drug. In this experiments, the problems of combining antioxidants with the surface of AgNPs were studied also.

Materials and Methods
Scutellaria baicalensis Georgi -Baikal skullcap have long been used in traditional medicine. This plants is one of species of Scutellaria which has 300 species [28,29]. Because of the high content of flavonoids, such as baicalin and baicalein Scutellaria baicalensis is the most studied specie in this group. The flavonoids which is isolated from S. baicalensis leafs and from roots have a wide range of pharmacological appling and are bioactiv molecules [30,31]. Now the extracts from S. baicalensis widly use in medicine of Russia, China, and other many countries. There are data that the roots of Baikal skullcap has very higher content of baicalin and baicalein compared to other organs. Therefore the roots of Baikal skullcap is more interesting for such purposes. Currently, the skullcap roots are more harvested and used for baicalin and bacalein production.
Extracts from root of this plants are using as pharmaceuticals for the many diseases. In some results of researchers, shows however that the shoot extract also had a greater biological activity.

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Copyrights @ Ahmadov IS. Arch Nano Op Acc J 110 hours -4, after 15 days -5, after 1 month -6). The synthesized silver nanoparticles were analyzed for UV -visible spectroscopic studies after the time duration of 24 hours, 15 days and 1 month. Based on the absorption spectra, the biosynthesized Ag nanoparticles by root extract showed surface plasmon resonance bands at about 414nm-461nm interval as shown in (Figure 3). It is identified that the absorption peaks and intensity are change dependence on the exposition and methods of extract preparation. Since was obtained that during increase exposition time the peak of absorption shifted from 447nm to 461nm in first variant of extract. It shows that in this case the size of Ag nanoparticles increases. This trend is also observed when the Ag nanoparticles were synthesized by the second variant of extract preparation as the peak of absorption shifted from 414nm to 456nm.

FTIR analysis
It is suggested that the biological molecules in plant extract is playing the dual role in the synthesis of metal nanoparticles. They are as a reducing and stabilizing or capping agent. These ability of plant extracts is recognized by comparing the FT-IR spectra of pure plant extract and extract mediated with Ag nanoparticles. FTIR analysis is one of appropriate method for the identification possible functional groups of biomolecules which performs the stabilization factors in the formation of AgNPs (Figure 4). showed the FT-IR spectra of pure powder of root .  730cm -1 (weak-medium C-C skeleton vibration -rocking). The shifts, corresponding to amine, amide and C-O functional groups, show the coordination between zero-valent silver and above-mentioned groups. Absence of peek, corresponding to carbonyl group, shows that reduction goes through these groups. According to the data of other authors for the C-N stretch vibrations corresponds to peaks at 1382cm -1 , as well as to the amide I bands of proteins [33].
The peak at 1074cm -1 corresponds to the linkages and shows the presence of flavanones on the surface of nanoparticles [34]. The peaks 1315-1037cm -1 and 1456-1600cm -1 regions corresponds to the phenolic groups of the plant extract [35]. For the C=C stretching in the aromatic ring corresponds to the peak 1592cm -1 and confirm the presence of the aromatic group [36]. They we can assume that flavonoids in the extract of Scutellaria baicalensis might be actively involved and responsible for the reduction of Ag + to Ag0 [37].

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Copyrights @ Ahmadov IS. Arch Nano Op Acc J 111 the view of the sample at 80 000× magnification which stands for examining area of about 1.2mkm surface. İn the examined area, one can notice the presence of nanoparticles of sizes within 16.19nm and 18.8nm. Parts (b,c,d) of the figure represents the view of the sample at 220 000× , 330 000× , 500 000× magnification respectively. SEM images showed that most of the silver nanoparticles are predominately spherical in shape having smooth surface and well dispersed with close compact arrangement. The smallest size of nanoparticle was found around 7.12nm. The SEM images shows that nanoparticles may direct contact even within the aggregates, indicating that stabilizater agents act [38]. During the aggregations the small nanoparticles become larger. In (Figure 6) are shown the SEM pictures of synthesized Ag nanoparticles. Usually Ag nanoparticles show at 3 keV a typically strong signal peak , due to surface plasmon resonance [39,40]. In the ( Figure 6). are shown the results of elements analysis of the sample which contains Ag nanoparticles. It is clear from fig.6 that elements such as Ag, O, C, K, Cl, Ca and Na are in the it.

Conclusion
In conclusion, there has been a great increasing interest in green synthesis of Ag nanoparticles. In this study, Ag nanoparticles were synthesized by an ecofriendly and convenient method using the Scutellaria baicalensis root and leaf extracts at ambient temperature.

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Copyrights @ Ahmadov IS. Arch Nano Op Acc J 112 Scutellaria baicalensis may used as a reductant for the synthesis of silver nanoparticles. During biosynthesized of AgNPs are occurs color change of solution, the UV-Vis spectroscopic analysis shows that by absorbtion peak at 414nm-461nm interval nanoparticles quantitatively was monitored. Further characterization with SEM analysis shows that synsized AgNPs have a the spherical form, are polydisperse and size ranging from 7.12 nm to 18.8nm with an average size of 11.35nm.