There is an increasing commercial demand for nanoparticles due to their wide applicability in various areas such as electronics chemistry, catalysis, energy and medicine metallic nanoparticles are traditionally synthesized by wet chemical techniques where the chemicals used are quite often toxic and flammable. in this paper we described a cost effective and environment friendly technique for green synthesis of silver and iron nanoparticles from 1mM silver nitrate,1mM ferric chloride solutions through the extract of leafy vegetable amaranths viridis as a reducing agent. Nanoparticles were characterized by UV-VIS absorption spectroscopy, the surface plasmoressonance spectrum of silver and iron nanoparticles was obtained at 422nm and 261nm.SEM&EDAX data reveals silver and iron nanoparticles are spherical in shape. EDAX indicates the reduction of silver ions to elemental silver and iron ions to elemental iron.SEM determine the morphology and size of nanoparticles. zetapotencial of silver and iron nanoparticles are determined in water as a dispercant. Zetapotencial of silver and iron nanoparticles is found to -24.6mV and 28,8mV.the synthesized silver and iron nanoparticles have very good antimicrobial activity. This is the for the first time that any leafy vegetable was used for synthesis of nanoparticles.
Keywords: Green synthesis, SEM&EDAX , FTIR ,AFM, Zetapotencial, Antimicrobial activity
The field of nanotechnology is one of the active areas of research in modern material sciences. Nanoparticles exhibit completely improved properties based on specific characteristics such as morphology ,size, and distribution, new applications of nanoparticles and nanomaterials are emerging rapidly[1,2,3].silver nanoparticles are wide used in industry and have an inhibitory effect on no. of microorganisms .they have also been used in manufacture of ointment and creams to prevent infection of bones and wounds. synthesized of nanoparticles can take place by using various methods especially silver by chemical, electrochemical,gamma radiation,photochemical,laser ablationsand het vaporization[8.9] etc…However other metals and metal oxide nanoparticles can also prepared synthetically. Synthesis of different nanoparticles by microorganisms such as fungus, yeast, bacteria, algae,etc. Ha been reported. Iron nanoparticles are the most ubiquitous of the transition metals used for treating industrial sites contaminated with chlorinated organic compounds and to treat many types polychlorinated bi phenyls (pcBs) organ chlorine pesticides and chlorinated organic solvents .iron oxides are used extensively due to the development of preparation technology of nanometer powders. synthesis of iron nanoparticles by micro emulsion technique,hydro thermal synthesis,sonochemical approach,non aqueous route,and and thermal composition of organic iron precursor ,sol-gel technique,thermal decomposition of organic metal,microbial plasma synthesis,etc. and recently via green chemistry route.
The use of environmental benign materials like plant leaf extracts[53-55] , bacteria, fungi, and enzymes .for the synthesis of silver and iron nanoparticles officers numerous benefits of eco-friendliness and compatibility for pharmaceutical and other bio medical applications as they do not use toxic chemicals for the synthesis of protocol.
Chemical synthesis methods lead to presence of some toxic chemical absorbed on the surface that may have adverse affect in the medical applications. Green synthesis provides advancement over chemical and physical method as it is cost effective environment friendly, easily scaled up for large scale synthesis and in this method there is no need to use high pressure energy, temperature , and toxic chemicals. The most important applications of silver nanoparticles is in medical industry such as tropical ointments to prevent infection against burn and open wounds and iron nanoparticles is in medical and laboratory applications. It has applications in plastic, nanowires, coatings, nanofibers and textiles.
Here in, we report for the first time of silver and iron nanoparticles, reducing the silver and iron ions present in the solution of silver nitrate and ferric chloride by the leafy vegetable extract of Amaranthus viridis these biologically synthesized nanoparticles were found to be extremely effective against different bacterial pathogens. Common name of Amantharus viridis is totakura, Chinese spinach etc… it belongs to family amaranthaceous members of this family has simple leaves that are opposite or alternate it is cosmopolitan taxon or herbs. Amaranth levees are very good source of vitamins like vitamin A, B6, C and K. Riboflavin etc. And minerals including calcium, iron.mg, potassium, zinc, manganese ,leaves are high in proteins including amino acid lysine. It highly nutritious food. Seeds and leaves of amaranth are used as herbal remedies, leaves have been to be very effective in stopping diarrhea and hemorrhagic problems like excessive menstruation and also a wonderful astringent and make a great wash for skin problems like eczema and wonderful acne remedy, a good remedy for hair loss and premature graying, Amaranth also makes effective mouth wash for treating mouth sores, swollen gums. In this present study, Amaranthus viridis has been used for the synthesis of silver and iron nanoparticles by green route and characterized by spectral analysis.
Fig.1:A photo graph of Amaranthus viridis (totakura) leafy vegetable used in the silver and iron nanoparticles synthesis.
Materials and Methods
Synthesis of nanoparticles from Amaranthus viridis extracts
Preparation of the Extract
Fresh leafy vegetable are collected, cut into fine pieces and dried at room temperature. Dried leaves are powdered and 3g of powder was weighed into 60 ml of Ro water and boiled for 10 min at 100oC.the extract was filtered through WhatmanNo.1 filter paper. The extract was stored at 40 C for further experiments.
Synthesis of Silver nanoparticles from Amaranthus viridis extract
The aqueous solution of 1mM silver nitrate (AgNO3) was prepared and used for the synthesis of silver nanoparticles. 5 ml of Amaranthus viridis extract was added into 5ml of aqueous solution of 1 mM silver nitrate for reduction into Ag+ ions. Here the filtrate acts as reducing and stabilizing agent for 1mM of AgNO3.
Synthesis of iron nanoparticles from Amaranthus viridis extract
The aqueous solution of 1mM ferric chloride (FeCl3) was prepared and used for the synthesis of iron nanoparticles. 5 ml of leaf extract was added into 5ml of aqueous solution of 1 mM ferric chloride for reduction into iron ions. Here the filtrate act as reducing and stabilizing agent for 1mM of FeCl3.
The Iron and Ag nanoparticles were characterized in a Nanodrop 8000 UV-VIS spectrophotometer, to know the kinetic behavior of Iron and Ag nanoparticles. The scanning range for the samples was 200-800 nm at a scan speed of 480nm/min. The spectrophotometer was equipped with “UVWinlab” software to record and analyze data. Baseline correction of the spectrophotometer was carried out by using a blank reference. The UV-Vis absorption spectra of all the samples were recorded and numerical data were plotted in the fig-3.
Scanning electron microscope (SEM)
In this present work Scanning Electron Microscopy (SEM)and EDX was performed by oxford Inca penta Fetx3 EDS instrument attached to Carl Zeiss EVO MA 15 Scanning electron Microscope (200kV) machine with a line resolution 2.32(in A0 ). These images were taken by drop coating AgNPs and iron nanoparticles on an aluminum foil. Energy dispersive Absorption Spectroscopy photograph of AgNPs were carried out by the SEM equipment, as mentioned above.
Zeta potential measurement.
Particle size and Zeta potential measurement experiments were carried out by using a Nanopartica (HORIBA).
The antimicrobial activity of silver and iron nanoparticles was evaluated against Gram positive: Staphylococcus aureus, Bacillus megaterium, Gram negative Escherichia coli (M&D), Pseudomonas aeruginosa, Klebsilla pneumonia by disc method. The 24h old cultures were prepared in nutrient broth (composition (g/l) peptone, yeast extract, sodium chloride, and D(+)-glucose).two replicas of respective microorganisms were prepared by spreading 100ul of revived culture on the nutrient agar plate (composition(g/l) peptone, yeast extract .sodium chloride(+)-glucose and agar-agar),with the help of spreader. Discs were prepared by using what man No.1 filter paper. The discs were placed on agar plates and sample of synthesized silver and iron nanoparticles were added on the disc with the help of micropipette. The plates were incubated at 370c overnight. Amoxyclav (Himedia SD063) disc was used as reference drug. The Bacterial strains of Microorganisms used for the determination of antibacterial activities of silver and iron nanoparticles synthesized were obtained from Department of Microbiology, S.V.University, Tirupathi .Different bacterial strains maintained on nutrient agar and subcultures were freshly prepared before use. Bacterial cultures were prepared by transferring two to three colonies into a tube containing 20 ml nutrient broth and grown overnight at 370c.
Results and Discussion
Amaranthus viridis Linn. (Amaranthaceae) is an annual herb, erect, 10 to 75 (-100) cm stem; slender, branched, angular, glabrous leaves. Commonly called as ‘Cholai’ in Hindi, which is grown in all regions of India, has been used in Indian and Nepalese traditional system to reduce labor pain and act an antipyretic . Other traditional uses range from an anti-inflammatory agent of the urinary tract, in venereal diseases, vermifuge, diuretic, antirheumatic, antidiabetic, antiulcer, analgesic, antiemetic, laxative, improvement of appetite, antileprotic, treatment of respiratory and eye problems and treatment of asthma [26-28] .
Furthermore, Amaranthus viridis contains antiproliferative and antifungal lactin properties as well as ribosome inactivating protein, β-carotene [29-30] and antiviral potential . Experimentally the plant evaluated for analgesic and antipyretic activities , in vitro anthelmintic  anti-inflammatory,antidiabetic, antihyperlipidaemic and antioxidant properties, Pharmacognostic study ,antinociceptive , antioxident & nutrient, heptaprotective activity.
Synthesis and characterization of nanoparticles
Synthesis of Ag and iron nanoparticles from plant extract.
Nanoparticles are synthesized according to the protocol discussed in “methods and materials” (section3). On mixing the extract with aqueous solution of the Ag ion complex for silver synthesis and FeCl3 for iron, a change in the color within 2min was observed for both the Nanoparticles. for silver nanoparticles color changes from colourless to yellowish brown colour where as for iron color changes from colorless to yellowish . It was due to the reduction of Ag+ and iron ions which indicates the formation of Ag and iron nanoparticles.
Characterization of nanoparticles
UV–Vis spectral analysis
UV-visible spectroscopy is important technique for analyzing the formation of silver and iron nanoparticles in aqueous solution AgNPs and iron has free electron, which gives rise to plasma resonance absorption band, due combined vibration of metal nanoparticles in resonance with the light wave. A surface plasma resonance spectrum of AgNPs and iron nanoparticles was obtained at 426nm and 259 nm after 2-3min color changing to light yellowish color in figure 2 the surface plasma AgNPs and iron nanoparticles at increasing concentration was taken and the color changes were observed for both nanoparticles .For silver color changes from colorless to yellowish brown color and for iron colorless to light yellowish brown color respectively. Metal nanoparticles can be synthesized by reducing metal ions using some chemical molecules .in green synthesis ,it is observed that natural material extract act as reducing agent for generation of metal nanoparticles. The uv visible spectrum of silver and iron nanoparticles its excitation also depending upon particle size , the earlier reports showed that for silver and iron nanoparticles the absorption peaks around 410-450nm and for iron 216-276 and above can be attributed to in size range 25-50nm .previous reports also reveals that particles in SPR region of around 410-450 nm and for iron 216-268nm cam attributed to spherical nanoparticles[42,43]. In present study SPR of silver and iron nanoparticles are 426 and 259nm, which are spherical in shape further confirmed by SEM ,particle size analysis and AFM studies.
SEM and EDX analysis of Ag and iron nanoparticles
The Morphology and size of nanoparticles in solution is determined by SEM images . It shows both nanoparticles are spherical in shape spectrum around .the EDX data shows very strong signal which indicate the reduction of silver ions into elemental silver and iron ions to elemental iron ions and are possibly originated from the molecules attached to the surface of iron and silver nanoparticles (figure 5). Similarly earlier report showed silver and nanoparticles showed an EDX spectrum, emission energy at 3 KeV and some of the weak signals from Cl, K ,O ,Ca ,Mg were observed
The electrostatic repulsive forces between the nanoparticles depends on the charge, when they are negatively charged prevents the nanoparticles from agglomeration in the medium leading to the long term stability .in the present study the higher negative value of zeta potentials confirms the repulsion among the particles and their by increases in stability of formulations .The zeta potential of the synthesized silver and iron nanoparticles is determined in water as a dispercant .The zeta potential is found to be -24.6 mV and 28.8mV.
The nanoparticles synthesis by green route was found extremely against 6 bacterial species at a concentration of 20µl Ag and iron nanoparticles, Gram positive. Bacillus megaterium, Staphylococcus aures, Gram negative..Escherichia coli (M), Escherichia coli (D), Pseudomonas aeruginosa, Klebsiella pneumonia. The results are shown in table 1 were comparable with reference drug viz. Amoxyclav (himedia SD063).
The antimicrobial activity of silver was recognized by clinicians for over 100 years . It is only in large few decades the action of silver and iron nanoparticles as an antimicrobial agent has been studied. . Aparna et al reported the antimicrobial activity against pseudomonas florescens ,E.coli, lactobacillus ,s.aureus.Sundarm Moorthi.C et al investigated the antimicrobial activity of silver nanoparticles against staphylococcus aures, bacillus subtilis, E.coli, psuedomonus aeuroginosa. Rout Rajesha et al. investigated the antibacterial activity of phytosynthesised silver nanoparticles against staphylococcus aures, E.coli ,p.aeuroginosa, and k.pneumonia. Similarly, Kim et al.  Reported antimicrobial activity of silver nanoparticles against E.coli and s. aures. The effect was dose dependent.
The antimicrobial activity of FeO nanoparticles on .E.coli and staphylococcus aureus was determined by Saba A.Mahdy by MTT assay . M.Senthil et al.  reported the antimicrobial activity of iron nanoparticles was performed against pseudomonas aeruginosa using agar well diffusion method. The cultures shown zone of inhibition which was about 1.6,2.2,2.8,3.2,2.6,2.7cm for Ag nanoparticles and 1.7,1.7,1,2,2,1.4 for iron nanoparticles in diameter respectively(table 1). The culture of Escherichia (D) shows maximum zone of inhibition for both nanoparticles.
The leaf extract Amaranthus viridis is found suitable for simple and rapid extraction of Ag and iron nanoparticles by green synthesis within 5- 10min.The spectroscopy characterization from UV-Vis, SEM, and EDX support the formation and stability of the biosynthesized AG and iron nanoparticles. This is a very simple and rapid method of green synthesis of Ag and iron nanoparticles which can be useful in various biomedical and biotechnological applications.
The iron and silver nanoparticles of average sizes have been synthesized using dried leaves of plant Amaranthus viridis. Characterizations from UV-Vis, SEM, EDX, Support the stability of biosynthesized nanoparticles. The silver and iron nanoparticles using Amaranthus proved excellent antimicrobial activity. These silver and iron nanoparticles may used in food and pharmaceutical industries. Why we are prefer this green synthesis means it provides advancement over chemical and physical method as it is cost effective, environment friendly, easily scaled up for large scale synthesis and in this method there is no need to use high pressure, energy temperature and toxic chemicals. so our ancients advice the people mainly prefer leafy vegetables for their daily food items because of these medicinal values.
-  jahn J. struct. Biol. 127, 106(1999)
-  H.S. Naiwa Ed. HandBook of Nanostructural Materials and Nanotechnology Academic press New York 1-5. (2000)
-  C.J.Murphy , J.Mater Chem. 18,2173-2176 (2008)
-  S.A. vorobyova, A.I. Lesnikovich and N.S. sobal. Colloids and surfaces A: physiochemical and engineering Aspects. 1999. 152, 375-379.
-  S.H. chol, Y.P. Zhang, A.Gopalam, K.P. Lee and H.D. khang colloids and surfaces. A: physic chemical and engineering Aspects. 2005.256.165-170.
-  Z. Li, Y.Li, x.F. Qian, J.Yin and Z.K. Zhu. Applied surface sciences. 2005-250. 109-116.
-  T. Tsuji, N.watanabe and M.Tsuji. Applied surface sciences . 2003, 211 . 189-193
-  Bae CH, Nam SH, park SM. Formation of silver nanoparticles by laser ablation of a silver target in NaCl solution .Appl Surf Sci. 2002; 197-198:628-634.
-  Smetanaa AB, Klabunde KJ, Sorensen CM. synthesis of spherical silver nanoparticles by digestive ripening, stabilization with various agents, and their 3-D and 2-D super-lattice formation. J colloid Interface Sci. 2005:284:521-526.
-  Zhou, Z.H.; wang,J.; Liu, X.; Chan, H.S.O.J. mater.chem.11,1704(2001).
-  Zhou, Z.H.; wang,J.; Liu, X.; Chan, H.S.O.J. phys.chem.c,113,16007(2009).
- Wang,X.;Zhuang,J.;Peng,Q.;Li,Y.Dnature,437,121(2005). kumar,r.v.;koltypin,Y.;XU,X.n.;Yeshurun,Y.;Gerdanken,A.;Felner,I.J.Appl.phys.89,6324(2001).
- Pinna, N.; Garnweitner,G.; Antonielti,M.; Niedeberger,M.J-Am.chem.soc.127,5608(2005).
- M.N Nadagouda, R.S.varma, Green chem.8, 516 (2006).
-  J.F.Liu, Z.S. Zhao, G. B. Jiang, Environ. Sci.Technol. 42, 6949(2008).
-  N. A. Begum, S. Mondal, S. Basu, R. A. Laskar, D. Mandal Colloids and Surfaces B: Biointerfaces 71(1), 113-118 (2009).
-  H. Bar, D. K. Bhui, G. P. Sahoo, P. Sarkar, S. P. De, A. Misra. Colloids and Surfaces A: Physicochemical and Engineering Aspects 339, 134–139 (2009).
-  J. Y. Song, B. S. Kim Bioprocess Biosyst. Eng. 32, 79–84 (2009).
-  V. Parashar, R. Parashar, B. Sharma, A. C. Pandey Digest Journal of Nanomaterials and Biostructures 4(1), 45 – 50 (2009).
-  N. Saifuddin, C. W. Wong, A. A. N. Yasumira E-Journal of Chemistry 6(1), 61-70 (2009).
-  K. C. Bhainsa, S. F. D’Souza Colloids and Surfaces B: Biointerfaces 47, 160–164 (2006).
-  B. Willner, B. Basnar, B. Willner FEBS J 274, 302–309 (2007).
-  Kirtikar KR, Basu BD. Indian Medicinal Plants. Vol. 3. 2nd ed. In: Kirtikar KR, Basu BD (eds). Dehra Dun, India: International book d distributors; 1987,p. 2061-2062.
-  Council of Scientific and Industrial Research (CSIR). Publications and Information Directorate. The Wealth of India. Vol. 1. A Dictionary of Indian raw materials and industrial products. New Delhi, India; 1988,p. 221.
-  Agra MF, Baracho GS, Nurit K, Basilio IJLD, Coelho VPM. Effect of methanolic extr act of Amaranthus viridis (MEAV) on hot plate test in mice. Brazil. J Ethnopharmacol 2007; 111(2):283-395.
-  De Fatima Agra M, Silva KN, Basilio IJLD, De Freitas PF, Filho JMB. Survey of medicinal plants used in the region northeast of Brazil. Braz J Pharmacognosy 2008; 18(3): 472-508.
-  Kaur N, Dhuna V, Kamboja SS, Agrewala JN, Singh J. A novel antiproliferative and antifungal lactin from Amaranthus viridis Linn. seeds. Protein Pept Lett 2006; 13(9):897- 905.
-  Kwon SY, An CS, Liu JR, Pack KH. A Ribosome inactivating protein from Amaranthus viridis. Biosci Biotechnol Biochem 1997; 61(9):1613-1614.
-  Obi RK, Iroagba II, Ojiako OA. Virucidal potential of some edible Nigerian vegetables. Afr J Biotechnol 2006; 5(19):1785-1788.
-  Bagepalli Srinivas Ashok Kumar, Kuruba Lakshman, Korala Konta Narsimha Jayaveera, Devangam Sheshadri Shekar, Chinna SwamyVel Muragan, Bachappa Manoj. Antinociceptive and antipyretic activities of Amaranthus viridis Linn. in different experimental models. Avicenna J Med Biotech 2009; 1(3): 167-171.
-  Ashok Kumar B.Sa, Lakshman Ka, Jayaveera K.Nc, Ranganayakulu Dd, Manoj baad. In vitro anthelmintic propertiy of methanol extract of Amaranthus viridis Linn. EJEAF Che 2010; 9(6):1093-1097.
-  Sravan Prasad Macharla,Venkateshwarlu Goli, K Vijaya Bhasker, Suvarna Devi P. Ch. Dhanalakshmi, Ch. Sanjusha. Effects of anti-inflammatory activity of Amaranthus viridis Linn. Annals of Biological Research 2011, 2 (4): 435-438.
-  Ashok Kumara BS, Lakshmanb K, Jayaveeac KN, Sheshadri Shekard D, Saleemulla Khane,Thippeswamy BS, Veeresh Veerapurg. Antidiabetic, antihyperlipidemicand antioxidant activities of methanolic extract of Amaranthus viridis Linn. in alloxan induced diabetic rats. Experimental and Toxicologic Pathology 2012; 64:75-79.
-  Musharaf Khan, Shahana Musharaf, Mohammad Ibrar, Farrukh Hussain. Pharmacognostic evaluation of the Amaranthus viridis L. Research In Pharmaceutical Biotechnology 2011; 3(1):11-16.
-  Ashok Kumar, B.S., Lakshman K., Jayaveera K.N.,Sheshadri Shekar D.,Vivek C. Antinociceptive and antipyretic activities of Amaranthus viridis Linn. in different experimental models Arch. Biol. Sci., Belgrade 2010; 62 (2):397-402.
-  Nisha Sharma, Gupta P.C, Ch V Rao. Nutrient content, mineral content and antioxidant activity of Amaranthus viridis leaves. Research Journal of medicinal plant, 2012;69(3):253-259.
-  Lakshman K. Hepatoprotective and antioxidant activities of Amaranthus viridis. Maced J Med Sci 2011; 1-6.
-  Mock, JJ, Barbic, M.; Smith, D.R. Schultz, S: Localized surface Plasmon resonance effects by naturally occurring Chinese yam particles.J. Chem. Phys., 116,6755-6759(2002).
-  Panacek.A, L. Kvietk, R. prucek, M. kolar, R. Vecerova, N. Pizurova, V.K. Sharma, T.Neveena, R. Zboril: Silver colloid nanoparticles: synthesis, characterization, and their antibacterial activity. J. Phys. Chem. B 110, 16248-16253(2006).
-  Zaheer.Z, Rafiuddin: Silver nanoparticles to self-assembled films: green synthesis and characterization. Collids Surf. B90, 48(2012).
-  Kasi Gopinath, Shanmugam Gowri, Ayyakannu Arumugam: Phytosynthesis of silver nanoparticles using pterocarpus santalinus leaf extract and their antibacterial properties. Journal of Nanostructure in Chemistry. 3, 68(2013)
-  Vanaja, M, Gnanajobitha, G, Paulkumar , K, Rajeshkumar, S, Malarkodi, C, Annadura, G: phytosynthesis of sliver nanoparticles bye Cissus Quadrangularies: influence of physicochemical factors. J. Nanostructure Chem. 3, 17 (2013).
-  A.K. Suresh , M.J. Doktycz, W. wang, J.W. Moon, B.Gu, H.M. Meyer III, D.K. Hensley, D.P. Allison , T.J. Phelps, D.A. Pelletier, Acta Biomater. 7(2011)4253.
-  A.Caceres, H. Menendez, E. Mendez, E. Cohobon, B.E. Samayao, Jauregui, E.Peralta, G. Carrillo. J. Ethnopharmacol . 48 (1995) 85-88.
-  Caceres. A, H. Mendez, E. Cohobon, B.E. samayao, E. Jauregui, E.peralta, G. Carrillo: Antigonorrhoeal activity of plants used in Guatemala for the treatment of sexually transmitted diseases. J. Ethnopharmacol. 48,85-88(1995).
-  Sundaramoorthi.C : Antimicrobial and woundhealing activity of silvernanoparticles.IJPRD/2022/PUB?ARTI/VOV-2/ISSUE12/FEB/010.ISSN 0974-9446.
-  W. Rout Rajesh, R.Lakkakula Jaya, S.kolekar Niranjan, D.Mendhulkar Vijay, B.kashid Sahebrao , Curr. 5(2009) 112-117.
-  J.S.Kim, E.Kuk, K.N. Yu, J.H. Kim, S.J.Park ,H.J. Lee, S.H. Kim, Y.K. Park, Y.H Park, C.Y. Hwang, Y.K. Kim , Y.S.Lee, D.H. Jeong , M.H. Cho, Nanomed ,: Nanotechnol. Biol. 3(2007)95-101.
-  Saba A.Mahdy .International Journal of Modern Engineering Research (IJMER) www.ijmer.com Vol.2, Issue.1, Jan-Feb 2012 pp-578-581 ISSN: 2249-6645.
-  senthil, C. Ramesh. Digest Journal of Nanomaterials and Biostructures vol.7, No.3, October- December 2012, p.1655-1660.
. Kotakadi, V.S., Subba Raoa, Y., Gaddam, S.A., Prasad, T.N.V.K.V., Varada Reddy, A., Sai Gopal, D.V.R.: Simple and rapid biosynthesis of stable silver nanoparticles using dried leaves of Catharanthus roseus Linn. G. Donn and its anti microbial activity. Colloids Surf B Biointerfaces 105, 194–198 (2013)
. Subba Rao, Y., Kotakadi, V.S., Prasad, T.N.V.K.V., Varada Reddy, A., Sai Gopal, D.V.R.: ‘‘Green synthesis and spectralncharacterization of silver nanoparticles from Lakshmi tulasi (Ocimum sanctum) leaf extract’’ Spectrochim. Acta A 103, 156–159 (2013)
. Kotakadi, V.S., Gaddam, S.A., Subba Rao, Y., Prasad, T.N.V.K.V., Varada Reddy, A., Sai Gopal, D.V.R.: Biofabrication of silver nanoparticles by Andrographis paniculata. Eur J. Chem 73, 135–140 (2014)
 Susmila Aparna Gaddam;Venkata subbaiah kotakadi;D.V.R Sai Gopal;y.subba rao; J Nanostruct Chem (2014) 4:82DOI 10.1007/s40097-014-0082-5