Journal of Nanoparticle Research

, Volume 12, Issue 1, pp 237–246 | Cite as

Process variables in biomimetic synthesis of silver nanoparticles by aqueous extract of Azadirachta indica (Neem) leaves

  • A. Tripathy
  • Ashok M. Raichur
  • N. Chandrasekaran
  • T. C. Prathna
  • Amitava Mukherjee
Research Paper


Owing to widespread applications, synthesis and characterization of silver nanoparticles is recently attracting considerable attention. Increasing environmental concerns over chemical synthesis routes have resulted in attempts to develop biomimetic approaches. One of them is synthesis using plant parts, which eliminates the elaborate process of maintaining the microbial culture and often found to be kinetically favourable than other bioprocesses. The present study deals with investigating the effect of process variables like reductant concentrations, reaction pH, mixing ratio of the reactants and interaction time on the morphology and size of silver nanoparticles synthesized using aqueous extract of Azadirachta indica (Neem) leaves. The formation of crystalline silver nanoparticles was confirmed using X-ray diffraction analysis. By means of UV spectroscopy, Scanning and Transmission Electron Microscopy techniques, it was observed that the morphology and size of the nanoparticles were strongly dependent on the process parameters. Within 4 h interaction period, nanoparticles below 20-nm-size with nearly spherical shape were produced. On increasing interaction time (ageing) to 66 days, both aggregation and shape anisotropy (ellipsoidal, polyhedral and capsular) of the particles increased. In alkaline pH range, the stability of cluster distribution increased with a declined tendency for aggregation of the particles. It can be inferred from the study that fine tuning the bioprocess parameters will enhance possibilities of desired nano-product tailor made for particular applications.


Biomimetic process Azadirachta indica Silver nanoparticles Process variability Shape anisotropy Size aggregation Synthesis Plant biotechnology 



The authors would like to thank Pro-Chancellors of VIT-University, Dean of School of Biotechnology and Division Leader of Environmental Biotech group for wholehearted cooperation. They also wish to acknowledge Ms Charumathi for carrying out a few preliminary experiments on pH effect.


  1. Ahmad A, Mukherjee P, Senapati S, Mandal D, Khan MI, Kumar R, Sastry M (2003) Extracellular biosynthesis of silver nanoparticles using the fungus. Fusarium oxysporum. Colloids Surf B Biointerfaces 28:313–318. doi: 10.1016/S0927-7765(02)00174-1 CrossRefGoogle Scholar
  2. Ankamwar B, Chaudhary M, Murali S (2005) Gold nanotriangles biologically synthesized using tamarind leaf extract and potential application in vapor sensing. Synth React Inorg Metal Org Nanometal Chem 35:19–26CrossRefGoogle Scholar
  3. Buffat PA (2003) Electron diffraction and HRTEM studies of multiple twinned structures and dynamical events in metal nanoparticles: facts and artefacts. Mater Chem Phys 81(2–3):368–375. doi: 10.1016/S0254-0584(03)00024-5 CrossRefGoogle Scholar
  4. Chang LT, Yen CC (1995) Studies on the preparation and properties of conductive polymers. VIII. Use of heat treatment to prepare metallized films from silver chelate of PVA and PAN. J Appl Polym Sci 55(2):371–374. doi: 10.1002/app.1995.070550219 CrossRefGoogle Scholar
  5. Chen B, Gao M, Zuo JM, Qu S, Liu B, Huang Y (2002) Binding energy of parallel carbon nanotubes. Surf Sci 520:7. doi: 10.1016/S0039-6028(02)02313-0 CrossRefGoogle Scholar
  6. Esumi K, Tano T, Torigoe K, Meguro K (1990) Preparation and characterization of bimetallic Pd–Cu colloids by thermal decomposition of their acetate compounds in organic solvents. Chem Mater 2:564–567. doi: 10.1021/cm00011a019 CrossRefGoogle Scholar
  7. Gardea-Torresdey JL, Gomez E, Peralta-Videa JR, Parsons JG, Troiani M, Jose-Yacaman H (2007) Alfalfa sprouts: a natural source for the synthesis of silver nanoparticles. Langmuir 19:1357–1361. doi: 10.1021/la020835i CrossRefGoogle Scholar
  8. Hall BD (2000) Debye function analysis of structure in diffraction from nanometer-sized particles. J Appl Phys 87(4):1666–1675. doi: 10.1063/1.372075 CrossRefADSGoogle Scholar
  9. Joerger R, Klaus T, Granqvist CG (2000) Biologically produced silver-carbon composite materials for optically functional thin-film coatings. Adv Mater 12(6):407–409. doi: 10.1002/(SICI)1521-4095(200003)12:6<407::AID-ADMA407>3.0.CO;2-O CrossRefGoogle Scholar
  10. Klaus T, Joergere R, Olsson E, Granqvist CG (2001) Bacteria as workers in the living factory: metal-accumulating bacteria and their potential for materials science. Trends Biotechnol 19:15–20. doi: 10.1016/S0167-7799(00)01514-6 CrossRefGoogle Scholar
  11. Liz-Marzan LM, Lado-Tourino I (1996) Reduction and stabilization of silver nanoparticles in ethanol by nonionic surfactants. Langmuir 12:3585–3589. doi: 10.1021/la951501e CrossRefGoogle Scholar
  12. Matejka P, Vlckova B, Vohlidal J, Pancoska P, Baumruk V (1992) The role of triton X-100 as an adsorbate and a molecular spacer on the surface of silver colloid: a surface-enhanced Raman scattering study. J Phys Chem 96(3):1361–1366. doi: 10.1021/j100182a063 CrossRefGoogle Scholar
  13. Mock JJ, Barbic M, Smith DR, Shultz DA, Shultz S (2002) Shape effects in plasmon resonance of individual colloidal silver nanoparticles. J Chem Phys 116:6755–6759CrossRefADSGoogle Scholar
  14. Mukherjee P, Ahmad A, Mandal D, Senapati S, Sainkar SR, Khan MI, Parishcha R, Ajaykumar PV, Alam M, Kumar R, Sastry M (2001) Fungus mediated synthesis of silver nanoparticles and their immobilization in the mycelial matrix: a novel biological approach to nanoparticle synthesis. Nano Lett 1(10):515–519. doi: 10.1021/nl0155274 CrossRefADSGoogle Scholar
  15. Mulvaney P (1996) Surface plasmon spectroscopy of nanosized metal particles. Langmuir 12:788–800. doi: 10.1021/la9502711 CrossRefGoogle Scholar
  16. Nair B, Pradeep T (2002) Coalescence of nanoclusters and formation of submicron crystallites assisted by Lactobacillus strains. Cryst Growth Des 2(4):293–298. doi: 10.1021/cg0255164 CrossRefGoogle Scholar
  17. Pileni MP (2000) Fabrication and physical properties of self organized silver nanocrystals. Pure Appl Chem 72:53–65. doi: 10.1351/pac200072010053 CrossRefGoogle Scholar
  18. Ross IA (2003) Medicinal plants of the world, vol. 2: chemical constituents, traditional and modern uses. Humana Press Inc., Totowa, pp 81–118Google Scholar
  19. Sastry M, Mayyaa KS, Bandyopadhyay K (1997) pH dependent changes in the optical properties of carboxylic acid derivatized silver colloid particles. Colloids Surf A 127:221–228. doi: 10.1016/S0927-7757(97)00087-3 CrossRefGoogle Scholar
  20. Shankar SS, Ahmad A, Parsricha R, Sastry M (2003) Bioreduction of chloroaurate ions by geranium leaves and its endophytic fungus yields gold nanoparticles of different shapes. J Mater Chem 13:1822–1826. doi: 10.1039/b303808b CrossRefGoogle Scholar
  21. Shankar SS, Rai A, Ahmad A, Sastry M (2004) 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. doi: 10.1016/j.jcis.2004.03.003 CrossRefPubMedGoogle Scholar
  22. Sharverdi AR, Mianaeian S, Shahverdi HR, Jamalifar H, Nohi AA (2007) Rapid synthesis of silver nanoparticles using culture supernatants of Enterobacteria: a novel biological approach. Process Biochem 42:919–923. doi: 10.1016/j.procbio.2007.02.005 CrossRefGoogle Scholar
  23. Shiraishi Y, Toshima N (2000) Oxidation of ethylene catalyzed by colloidal dispersions of poly(sodium acrylate)-protected silver nanoclusters. Colloids Surf A Physicochem Eng Asp 169:59–66. doi: 10.1016/S0927-7757(00)00417-9 CrossRefGoogle Scholar
  24. Siddiqui S, Mahmood T, Siddiqui BS, Faizi S (1986) Isolation of a triterpenoid from Azadirachta indica. Phytochemistry 25(9):2183–2185. doi: 10.1016/0031-9422(86)80087-5 CrossRefGoogle Scholar
  25. Siddiqui BS, Afshan F, Gulzar T, Hanif M (2004) Tetracyclic triterpenoids from the leaves of Azadirachta indica. Phytochemistry 65:2363–2367. doi: 10.1016/j.phytochem.2004.04.031 CrossRefPubMedGoogle Scholar
  26. Sun YP, Atorngitjawat P, Meziani MJ (2001) Preparation of silver nanoparticles via rapid expansion of water in carbon dioxide microemulsion into reductant solution. Langmuir 17(19):5707–5710. doi: 10.1021/la0103057 CrossRefGoogle Scholar
  27. Vigneshwaran N, Ashtaputre NM, Varadarajan PV, Nachane RP, Paralikar KM, Balasubramanya RH (2007) Biological synthesis of silver nanoparticles using the fungus Aspergillus flavus. Mater Lett 61:1413–1418. doi: 10.1016/j.matlet.2006.07.042 CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  • A. Tripathy
    • 1
  • Ashok M. Raichur
    • 2
  • N. Chandrasekaran
    • 1
  • T. C. Prathna
    • 1
  • Amitava Mukherjee
    • 1
  1. 1.School of Biotechnology, Chemical and Biomedical EngineeringVIT UniversityVelloreIndia
  2. 2.Department of Materials EngineeringIndian Institute of ScienceBangaloreIndia

Personalised recommendations