2. OUTLINES
• Definition
• History
• Synthesis of nanoparticles
• Effect of nanoparticles and there target sites
• Factors that influence the antimicrobial activity of NPs
• Factors which effect to produce well characterized NPs
• Application of nanoparticles in microbiology
3. Definition ..
• The prefix “Nano” in the term nanoparticles is derived from a Greek word
Nanos, which means “dwarf”.
• It relates to any engineered matter that is one billionth (ten power minus
nine 10−9m) in size or at least one of its dimension is in this size
• Nanoparticles are particles between 1 and 100 nanometers (nm) in size
with a surrounding interfacial layer.
• The interfacial layer is an integral part of nanoscale matter, fundamentally
affecting all of its properties.
• The interfacial layer typically consists of ions, inorganic and organic
• molecules.
• These coating molecules are known as stabilizers, capping and other
surface ligands
4. • Generally there are two parts of nanoparticles, the core material and
a interfacial layer (surface converter). The surface converter is
responsible for alteration in the physicochemical properties of core
materials.
5.
6. History about nanotechnology
• NPs lie in the field of nanotechnology.
• The concept of nanotechnology was first presented by Richard
Feynman through his famous lecture, entitled “There’s a plenty of
room at the bottom” at the American Institute of Technology.
• The word nanotechnology was introduced by Prof. Norio Taniguchi of
Tokyo Science University.
• Nanomaterials have in fact been used unknowingly for thousands of
years; for example, gold nanoparticles that were used to stain
drinking glasses also to cured certain diseases.
7. Synthesis of nanoparticles
• The different methods used for synthesis of nanoparticles are follows:
• 1. Physical method
• 2. Chemical method
• 3. Biological method
• 1. Physical method :-
• This method require special equipment's or operational control.
• The physical method often called top-down approach which includes
methods like diffusion, irradiation, thermal decomposition and arc
discharge etc.
8. • These approaches use larger initial structures or macroscopic units which
can be externally controlled in the processing of nanostructures .
• This top-down methods are not cheap and quick to manufacture but this
method is slow and not suitable for large scale production.
• 2. Chemical method :-
• Mostly the chemical methods of synthesis of nanoparticles are the bottom
up approaches.
• These approaches include the miniaturization of material components (up
to atomic level)with further self-assembly processes leading to the
formation of nanostructures.
• This method of synthesis of nanoparticles is cheap and quick to
manufacture. This method is also slow and not suitable for the large scale
production.
10. Disadvantages of Synthesis of nanoparticles by
physical and chemical methods
• The chemical and physical methods are harmful in one or the other
way, as the chemicals used are toxic, flammable and do not dispose of
in the environment easily.
• These methods lead to presence of toxic chemicals adsorbed on the
surface of nanoparticles that may have adverse effect in the medical
applications.
• Many of these method are expensive and unstable.
• Sometime nanoparticles which we can produce by this methods have
many side effects and are toxic so we cannot use them in medical or
pharmacological purpose.
11. • In short the physical and chemical techniques tend to be capital-intensive,
inefficient in materials and require high amount of energy, and may require
toxic or environmentally harmful chemicals.
• 3. Biological method :-
• In this method plant, microorganism and their products are used for the
synthesis NPs.
• This method is inexpensive, clean, nontoxic, and eco friendly.
• In this type of approach the formation of nanoparticles occurs due to
reduction/oxidation of a metal, and the agents mainly responsible for these
processes are different enzymes which are secreted by microbial systems
or plants.
• Major drawbacks associated with the biosynthesis of NPs are tedious
(slow) purification steps and poor understanding of the mechanisms.
12. 3. Biological method :-
• Nanoparticle Synthesis Using Microorganisms :-
• Over the past few years, microorganisms, including bacteria, fungi,
and yeasts, have been studied extra- and intracellularly for the
synthesis of metal nanoparticles.
• Among the various methodologies, extracellular synthesis has
received much attention because it eliminates the downstream
processing steps required for the recovery of nanoparticles in
intracellular methodologies, including sonication to break down the
cell wall, several centrifugation and washing steps required for
nanoparticle purification.
13. • Microorganism can synthesis nanoparticles by two ways:-
• 1) intracellular synthesis of NPs :-
• The intracellular method involves a special ion transportation in the
microbial cell.
• In the intracellular synthesis of nanoparticles, the cell wall of the micro
organisms plays an important role.
• The mechanism involves electrostatic interaction of the positive charge of
the metal ions with negative charge of the cell wall.
• The enzymes (reductase enzymes ) which are present within the cell wall
reduce the ions to nanoparticles and these nanoparticles get diffused off
through the Cell wall .
Nanoparticle Synthesis Using Microorganisms
14. • Steps in the synthesis of intracellular NPs:
• Culturing the microorganism and collect the biomass after growth.
• The biomass is centrifuged and washed thoroughly with sterile water
• Then dissolved in sterile water with a filter-sterilized solution of metal
salt.
• The reaction mixture is monitored by visual inspection for a color
change.
• After the incubation period, the biomass is removed by repeated
cycles of ultrasonication, washing, and centrifugation. These steps
help to break down the cell wall and enable the nanoparticles to be
released. The mixture is then centrifuged, washed, and collected.
15. Diagrammatic representation of intracellular synthesis of nanoparticles. N –nucleus,
NP – nanoparticles, +ve charge on metal ions, −ve = charges on the cell wall.
16. • 2) Extracellular synthesis of NPs :-
• Culturing the microorganisms for 1–2 days in a rotating shaker under
optimum conditions (including pH, temperature, medium components,
etc.).
• The culture is centrifuged to remove the biomass.
• The obtained supernatant (contain deferent reductase enzymes secreted
by microbes) is used to synthesize nanoparticles by adding a filter-sterilized
metal salt solution and is incubated again.
• The nanoparticle synthesis can be monitored by observing a change in the
color of the culture medium.
• After incubation, the reaction mixture can be centrifuged at different
speeds to remove any medium components or large particles.
• Finally, the nanoparticles can be centrifuged at high speed or with a
density gradient, washed thoroughly in water/solvent (ethanol/methanol)
and collected in the form of a bottom pellet.
17.
18. Nanoparticle Synthesis Using Plants
• For the synthesis of nanoparticles by plant extracts, the plant parts
(root, leaf, bark, etc.) are washed thoroughly with distilled water.
• Then cut into small pieces and boiled to perform the extraction.
• Next, the extract can be purified by filtration and centrifugation.
• Different ratios of plant extract, metal salt solution, and water
(depending on the plant species and parts) are used for nanoparticle
synthesis.
• This reaction mixture is incubated further to reduce the metal salt
and monitored for a change in color.
• After synthesis, the nanoparticles are collected by similar
methodologies as in microorganism-mediated synthesis.
19. Biological synthesis
Metal salt concentration plus plant
or microbes extracts.
production of
heterogeneous
NPs with low
yield
Optimization
Processing parameters:
1.Incubation period 2.Mixing ratio
3.Temperature 4. pH 5. Aeration
Stable production of
homogenous and
capped NPs with high
yield
Metal salts Metal
nanoparcles (NPs)
Modify processing parameters
20. Target site of NPs
• NPs have broad spectrum antimicrobial effect.
• The antibacterial activity of NPs results from their penetration into a
bacterium and attachment to the surface of a cell membrane.
• NPs cause disturbance in the energy production
• It also cause damage to the cell membrane, followed by the release of
cell contents.
• Ag NPs attack on Gram-negative bacteria by anchoring and
penetrating the cell wall, leading to structural changes in the cell
membrane that increase permeability.
21. • The antibacterial mechanisms associated with NPs are attributable to
the formation of free radicals that induce membrane damage.
• NPs interact strongly with thiol groups in enzymes and phosphorus-
containing bases and effect on there activity.
• NPs interaction (Ag NPs) with DNA may prevent bacterial cell division
and DNA replication, leading to bactericidal effect ( cause cell death).
• NPs may also interact in the electron transport chain.
• They also have antibacterial activity against spores that are resistant
to high temperature and high pressure.
22.
23. Factors that influence the antimicrobial activity of
NPs
• The antibacterial activity of nanoparticles is determined by their size,
shape, and concentration.
• Smaller nanoparticles exhibit higher toxicity toward bacterial
pathogens, as these nanoparticles likely diffuse more easily relative to
those larger in size.
• The antibacterial efficacy of nanoparticles is also influenced by their
shape.
• Triangular shape NPs > spherical shape NPs > rod shaped NPs.
• The antimicrobial activity is also influence by the concentration of
NPs.
24. Factor which effect to produce well
characterized NPs
• Selection of the best bacteria
• Selection of the biocatalyst state.
• Optimal conditions for cell growth and enzyme activity.
• Optimal reaction conditions.
• Extraction and purification processes.
• Stabilization of the produced NPs.
25. Application of NPs
• Recently, the diverse applications of metal nanoparticles have been
explored in biomedical, agricultural, environmental, and
physiochemical areas.
• NPs are used for the specific delivery of drugs i.e. gold NPs.
• NPs are also have been used for tumor detection and angiogenesis.
• NPs are used in the diagnosis of deferent genetic disorders.
• NPs are also used in the photoimaging, and photo thermal therapy.
26. • NPs have been applied for cancer therapy i.e. iron oxide NPs.
• NPs are also used in destruction of tumor via heating (hyperthermia),
drug delivery and tissue repair ( iron oxide NPs ).
• NPs is used in the cell labeling, targeting and immunoassays.
• NPs is used in the detoxification of biological fluids.
• NPs is also used in the magnetic resonance imaging (MRI), and
magnetically responsive drug delivery.
27. • NPs have also been used for many antimicrobial purposes as well as
anticancer and anti inflammatory purposes i.e. silver NPs.
• NPs are also used for wound treatment application because of there
biocompatible, non toxic, self cleaning, skin compatible antimicrobial
and dermatological behaviors.
• NPs is also used in the cosmetics and UV blocking agents for example
Zink and titanium are used for the sad purposes.
• NPs are also used for the preservation of deferent foods and other
food products because of there antimicrobial effect.
28. Application ….
• A list of some of the applications of nanomaterials to biology or medicine is given below:
• - Fluorescent biological labels
• - Drug and gene delivery
• - Bio detection of pathogens
• - Detection of proteins
• - Probing of DNA structure
• - Tissue engineering
• - Tumor destruction via heating (hyperthermia)
• - Separation and purification of biological molecules and cells
• - MRI contrast enhancement
• - Phagokinetic studies
