This document discusses green synthesis of nanoparticles using biological methods. It describes how nanoparticles can be synthesized using plant extracts, agricultural waste, microorganisms and enzymes in an environmentally friendly way. This is advantageous over chemical and physical methods as it is cost-effective, produces non-toxic nanoparticles and does not require high temperature or pressure. Specific examples discussed include using bacteria to synthesize silver nanoparticles and controlling factors like pH and temperature to regulate nanoparticle size and shape during microbial synthesis. Overall, the document presents biological methods as a green alternative for nanoparticle production.

1. Green synthesis of nanoparticles

2. TERMINOLOGIES
• Nanoparticles
Particles having atleast one dimension in the range of 1-100
nm
• Green Chemistry
Utilization of a set of principles that reduces or eliminates
the use or generation of hazardous substances in the
design, manufacture, and application of chemical products
• Green Synthesis of Nanoparticles
Use of biological routes such as those involving
microorganisms, plants etc. for the synthesis of
nanoparticles.

3. PRINCIPLES OF GREEN CHEMISTRY
1. Prevent Waste
2. Atom Economy
3. Less Hazardous Chemical Synthesis
4. Designing Safer Chemicals
5. Safer Solvents
6. Design for Energy Efficiency
7. Use of Renewable Feedstock
8. Reduce Derivatives
9. Catalysis
10. Design for Degradation
11. Real Time Analysis for Pollution Prevention
12. Inherently Safer Chemistry for Accident Prevention

4. DIFFERENT APPROACHES TO
NANOFABRICATION
2) TOP-DOWN APPROACH
1) Material is fragmented to yield a nanoparticle
2) Long Execution Time
1) BOTTOM-UP APPROACH
1) Assembling individual atoms and molecules to
form nanoparticle
2) Short Execution Time

5. SYNTHESIS METHODS
PHYSICAL METHOD CHEMICAL METHOD BIOLOGICAL METHOD
MECHANICAL METHODS CO-PRECIPITATION METHOD
SYNTHESIS USING PLANT
EXTRACTS
VAPOUR DEPOSITION SOL-GEL METHOD SYNTHESIS USING ENZYMES
SPUTTER DEPOSITION MICROEMULSIONS
SYNTHESIS USING
AGRICULTURAL WASTE
ELECTRIC ARC DEPOSITION HYDROTHERMAL SYNTHESIS
ION BEAM TECHNIQUE SONOCHEMICAL SYNTHESIS
MOLECULAR BEAM EPITAXY MICROWAVE SYNTHESIS

6. GREEN SYNTHESIS OF NANOMATERIALS
• Physical Method – time and energy consuming,
synthesis at high temp. and pressure
• Chemical Method – simple, inexpensive and low
temp. synthesis method, use of toxic reducing and
stabilizing agents makes it harmful
• Green Method – easy, efficient, and eco-friendly.
Eliminates the use of toxic chemicals, consume less
energy and produce safer products and by products
• Example – bacteria for Au, Ag, Zn and Fe NPs; yeasts
for Ag and Pb NPs; plants for Au, Ag, Pd and Pt NPs

7. BIOLOGICAL METHODS
• Used for synthesis of highly stable and well-
characterized NPs
• Rapid Synthesis, controlled toxicity and size
characteristics, economical and eco-friendly
• Sizes and morphologies controlled by altering
conditions such as pH, substrate concentration,
temperature, mixing speed and exposure time.
• Different Synthesis Methods
– Use of plant extracts
– Use of waste
– Use of enzymes and microorganisms

8. 1. SYNTHESIS USING PLANT EXTRACTS

10. ADVANTAGES
• Environmental friendly
• Easily scaled up for large synthesis of
nanoparticles
• No need of high temperature, pressure, energy
and toxic chemicals
• More advantageous over use of micro-organisms
by less elaborate process of maintaining cultures
• Reduces cost of micro-organism isolation and
their culture media

11. DISADVANTAGES
• Plants cannot be manipulated as the choice of
nanoparticles through optimized synthesis
through genetic engineering
• Plant produce low yield of secreted proteins
which decreases the synthesis rate

12. 2. SYNTHESIS USING WASTE

16. ADVANTAGES
• Easily available and does not require rigorous
processing
• Directly used for NP synthesis
• Option for waste management
• Leads to fast and cost effective approach
• Does not induce toxic NP

17. 3. SYNTHESIS USING
ENZYMES/MICROORGANISMS
• Microbial synthesis of nanoparticles is a green
chemistry approach that interconnects the fields of
nanotechnology and microbial biotechnology.
• A bottom-up approach used.
• Nanoparticle formation occurs due to the
reduction/oxidation of metallic ions.
• Nanoparticle formation can be either extracellular or
intracellular depending on the microorganism.
• Many bacteria, fungi and plants have the ability to
synthesize metallic nanoparticles and all have their
own advantages and disadvantages.

18. Example: Synthesis of Silver
nanoparticle by bacteria.
• Ag nanoparticles have been synthesized using
Pseudomonas stutzeri AG259 bacterium.
• Mechanism:
NADH
NAD+ e-
NADH dependent reductase enzyme
Ag +
Ag
nanoparticle

19. • Ag nanoparticles prepared were accumulated in periplasmic space
of bacteria and were 36-45 nanometer size.
• This bacteria in conc. aqueous solution of silver nitrate produce
nanoparticles upto 200 nm in size.
• Similarly, many other bacterial species are used like Escherichia
coli, Klebsiella pneumonia, Lactobacillus spp., Bacillus cereus,
Corynebacterium sp., and Pseudomonas sp., etc.
• Other microorganisms like actinomycetes, viruses, fungi, algae,
yeasts, are also used for nanomaterial synthesis.

20. • Advantages:
1. Clean, non-toxic, biocompatible and eco-friendly method for
synthesis of nanoparticles.
2. Cost effective, safe and sustainable.
3. Bacteria are easy to handle and can be easily manipulated.
• Disadvantages:
1. Culturing of micro-organisms is time-consuming.
2. Difficult to have control over size, shape and crystallinity.
3. Particles are not mono-dispersed and rate of production is slow.

21. CONCLUSION
• Different methods (physical, chemical and biological) have been
developed to obtain NPs of various shapes and sizes.
• Biological method of NPs is economically and environmentally
friendly alternative to chemical and physical approaches.
• It provide a new possibility of synthesizing NPs using natural
reducing and stabilizing agents.
• It has faster synthesis rates, controlled toxicity and well-
characterized NPs.
• This method is used in various areas such as pharmaceuticals,
cosmetics, foods and medical applications.

22. REFERENCES
• Ahmed, S., Ahmad, M., Swami, B.L., Ikram, S., 2016. A review on plants extract
mediated synthesis of silver nanoparticles for antimicrobial applications: A green
expertise. J. Adv. Res. 7, 17–28. doi:10.1016/j.jare.2015.02.007
• Kalishwaralal, K., Deepak, V., Ram Kumar Pandian, S., Kottaisamy, M., BarathManiKanth,
S., Kartikeyan, B., Gurunathan, S., 2010. Biosynthesis of silver and gold nanoparticles
using Brevibacterium casei. Colloids Surfaces B Biointerfaces 77, 257–262.
doi:10.1016/j.colsurfb.2010.02.007
• Makarov, V. V., Love, A.J., Sinitsyna, O. V., Makarova, S.S., Yaminsky, I. V., Taliansky, M.E.,
Kalinina, N.O., 2014. “Green” nanotechnologies: Synthesis of metal nanoparticles using
plants. Acta Naturae 6, 35–44. doi:10.1039/c1gc15386b
• Shah, M., Fawcett, D., Sharma, S., Tripathy, S.K., Poinern, G.E.J., 2015. Green synthesis of
metallic nanoparticles via biological entities, Materials. doi:10.3390/ma8115377
• Sharma, D., Kanchi, S., Bisetty, K., 2015. Biogenic synthesis of nanoparticles: A review.
Arab. J. Chem. doi:10.1016/j.arabjc.2015.11.002
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Fungi and Plants’; Nanomedicine & Nanotechnology ,2014 (vol 5).
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Jai Poinern: a review on Green Synthesis of Metallic Nanoparticles via Biological
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