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International Journal of Biological Technology (2010) 1(1):75-77.

Original Article

Biotechnological synthesis of gold nanoparticles of Azadirachta indica leaf extract

A.Thirumurugan∗, Jiflin.G.J, Rajagomathi.G, Neethu Anns Tomy, S.Ramachandran, and R.Jaiganesh School of Biotechnology and Health Sciences,∗Karunya University, Coimbatore- 641114, INDIA Kumaraguru College of Technology, Coimbatore- 641 006, INDIA; School of Bioengineering, SRM University, Chennai-603 203, INDIA; Email: biotechthiru@gmail.com Contact no: +91-9787177905 . Abstract Development of eco-friendly process for the synthesis of nanoparticles is one of the main steps in the area of nanotechnology research. Here, we studied the Biological synthesis of gold nanoparticles using Azadirachta indica plant leaf extract .The synthesized nanoparticles are confirmed by color changes and it was characterized by UV-visible spectroscopy. The plant based route could be considered to be an environmental friendly or green biological method of nanoparticles production. Key words: Gold nanoparticles, UV – visible spectroscopy, Azadirachta indica, HPLC.

Introduction Nowadays, the preparation of nanoscaled gold materials has become very important due to their unique properties, which are different from those of the bulk materials (Armendariz et al.,2004). The properties of these particles in applications as diverse as catalysis, sensors and medicine depend critically on the size and composition of the nanoparticles (Haverkamp et al.,2007). Production of nanoparticles can be achieved through mainly three methods such as, Chemical, Physical and Biological methods. Since noble metal nanoparticles such as gold, silver and platinum nanoparticles are widely applied to human contacting areas, there is a growing need to develop environmentally friendly processes of nanoparticles synthesis that do not use toxic chemicals. Biological methods of nanoparticles synthesis using microorganism, enzyme, and plant or plant extract have been suggested as possible ecofriendly alternatives to chemical and physical methods (Song and Kim,2008). Specifically, the study has been attempted bioreduction of chloroaurate ions or silver ions by the broths of geranium and neem (Shiv Shankar et al.,2004a;Shankar et al.,2004b). Also gold nanotriangles synthesisized using Tamarind leaf extract and studied their potential application in vapour sensing (Ankamwar et al.,2005). Most recently, a study has been demonstrated synthesis of gold nanotriangles and silver NPs using Aloe vera plant extracts (Chandran et al.,2006). Already some works have been reported on synthesis of gold nanoparticles by A. indica. In the present study we have investigated biosynthesis of gold © Gayathri Teknological Publication

nanoparticles by Azadirachta indica and concluded with reason for this synthesis. We used this plant leaf extract since this plant is easily available in our university campus itself and also in all over Tamil Nadu, India

Materials and Methods Collection and Extract Preparation Collected the plant leaves from our university campus itself, and allowed to dry for 2 weeks at room temperature. The plant A. indica was used. Leaves were dried at room temperature. The plant leaf broth solution was prepared by taking 5g of thoroughly washed and finely cut leaves in a 300mL Erlenmeyer flask with 100mL of sterile distilled water and then boiling the mixture for 5 min. They were stored at 4οC and used within a week. Synthesis and Characterization For the synthesis of Au- NPs (Gold nanoparticles), two boiling tubes were taken, one containing 10ml of 1mM Hydrogen tetra chloro aurate (Himedia, Mumbai) solution as control and the second flask containing 9ml of 1mM Hydrogen tetra chloro aurate solution and 1ml of plant leaf extracts as test solution were incubated at room temperature for 1-2 hours. The gold nanoparticle solution thus obtained was purified by repeated centrifugation at 15,000 rpm for 20 min. Supernatant is discarded and the pellet is dissolved in deionised water. The gold nanoparticules were confirmed by colour changes and qualitatively characterized by UVvisible spectrophotometer on a Perkin Elmer (Lamda 25)

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International Journal of Biological Technology (2010) 1(1):75-77.

Results and Discussion The color change showed the presence of gold nanoparticles in the Azadirachta indica leaf extract and it was characterized by UVVisible spectrophotometer and monitored by taking readings at regular time intervals in a Perkin Elmer (lambda25) UV–Visible spectrophotometer. The strong broad peak located at 550nm was observed for gold nanoparticles.

Fig.1: 1mM Hydrogen Tetra Chloro Aurate solution before adding extract (Azadiracda indica) (left), after adding extract to the solution

Fig. 2: Strong broad peak of gold nanoparticles Azadirachta indica leaf extract The color change showed the presence of gold nanoparticles in the A. indica leaf extract and it was characterized by UV-Visible spectrophotometer and monitored by taking readings at regular time intervals in a Perkin Elmer (lambda25) UV–Visible spectrophotometer. The strong broad peak located at 550nm was observed for gold nanoparticles. Gold nanoparticles were synthesized from Hydrogen tetra chloroaurate solution containing Au+ ions by treating with the leaf © Gayathri Teknological Publication

extract of Neem (A. indica). The supernatant of A. indica changed the Hydrogen tetra chloroaurate solution to a pink ruby red color within 15 minutes of reaction with the Au+ ions (as shown in Fig.1). The appearance of the pink ruby red color indicated the formation of gold nanoparticles. The gold nanoparticles initially confirmed by color changes and it was characterized by UV- Visible spectrophotometer. This technique has proved to be very useful for the analysis of nanoparticles. The UV- visible spectra showed a strong Plasmon resonance which was centered approximately at 550 nm (as shown in Fig.2). Observation of this strong broad plasmon peak has been well documented for various Me- NPs, with sizes ranging all the way from 2 to 100 nm (Henglein,1993). Sadeghian et al.,(2007) analysed the Azadirachta indica plant leaf extracts bioactive compounds by HPLC (Table I).Compared to all the other compounds the major bioactive compounds are found as Salanin, Nimbin, Azadirone and Azadirachtins and with this we can conclude the result that it may be one of the reasons for the reduction of gold nanoparticles. Conclusion In conclusion, the gold nanoparticles were synthesized using plant leaf extracts of Azadirachta indica as this plant is easily available in our university campus and all over Tamil Nadu, India. Initially synthesis was confirmed by color changes and Characterized by UV-visible spectroscopy. According to Sadeghian et al.,(2007) analysis the major bioactive compounds are Salanin, Nimbin, Azadirone and Azadirachtins in the Azadirachta indica plant leaf extract. With this we can conclude that it may be one of the reasons for the reduction of gold nanoparticles.

References Armendariz,V., et al.2004. Size controlled gold nanoparticle formation by Avena sativa biomass: use of plants in nanobiotechnology. Journal of Nanoparticle Research, 6: 377–382. Haverkamp, R.G. et al.,2007. Pick your carats: nanoparticles of gold–silver–copper alloy produced in vivo. Journal of Nanoparticle Research, 9:697–700. Song, J.Y. and Kim, B.S.2008. Rapid biological synthesis of silver nanoparticles using plant leaf extracts. Bioprocess Biosyst Eng.

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International Journal of Biological Technology (2010) 1(1):75-77.

Shiv Shankar, S, Rai A, Ankamwar B, Singh A, Ahmad, A, and Sastry, M.2004a. Biological synthesis of triangular gold nanoprisms. Nat Mater., 3:482–488 Shiv Shankar, S., Rai, A., Ahmad, A., and Sastry, M. 2004b. Rapid synthesis of Au, Ag, and bimetallic Au core–Ag shell nanoparticles using neem (Azadirachta indica) leaf broth. J. Colloid Interface Sci .,275:496-502 Ankamwar; B., Chaudhary, M., and Sastry, M. 2005. Gold Nanotriangles biologically Synthesized using Tamarind leaf extract and Potential application in vapor sensing. Synthesis and Reactivity in inorganic, metal-organic, and Nano-Metal Chemistry, 35:19- 26.

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Chandran S.P., Chaudhary, M., Pasricha, R., Ahmad, A. and Sastry, M.2006. Synthesis of Gold Nanotriangles and Silver Nanoparticles using Aloe vera plant extract. Biotechnology Progress,577 – 583. Henglein, A. 1993. Physicochemical properties of small metal particles in solution: "microelectrode" reactions, chemisorption, composite metal particles, and the atom-to-metal transition. J. Phys.Chem.,5457–5471. Sadeghian,M. M. and Azaienezhad, F.M. 2007. Investigation of compounds from Azadirachta indica (Neem). Asian Journal of Plant sciences, 6(2): 444-445.

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