>Nanoparticles >Core/Shell nanoparticles >Different Shaped Core/Shell Nanoparticles >Characterization of Core/Shell nanoparticle >Synthesis >Role of Nanotechnology in our life >Future Prospects >References

2. MR. SHAMOON AL ISLAM
DEPARTMENT OF PHYSICS
UNIVERSITY OF AGRICULTURE FAISALABAD

3. OUTLINE
 Nanoparticles
 Core/Shell nanoparticles
 Different Shaped Core/Shell Nanoparticles
 Characterization of Core/Shell nanoparticle
 Synthesis
 Role of Nanotechnology in our life
 Future Prospects
 References

4.  Nanoparticles are particles between 1 and 100 nanometers in size.
In nanotechnology, a particle is defined as a small object that
behaves as a whole unit with respect to its transport and properties
 Nanomaterials have, one or more dimension in the nanometer scale
and subsequently show novel properties from their bulk materials
like;
 Small size
 High surface area
 Ease to suspend in liquids
 Deep access to cells and organelles
 Improved physical, chemical & biological properties
Nanoparticles:

5. “To understand the very large, we must
understand the very small.”
- Democritus (400 BC)

6. Core/Shell nanoparticles
 Emerged at the frontier between materials chemistry and many other fields,
such as electronics, biomedical, pharmaceutical, optics, and catalysis.
 Core/shell nanoparticles are highly functional materials with modified
properties.
 Because of the shell material coating, the properties of the core particle such
as reactivity decrease or thermal stability can be modified, so that the overall
particle stability and dispersibility of the core particle increases.
 The purpose of the coating on the core particle are many fold, such as surface
modification, the ability to increase the functionality, stability, and
dispersibility, controlled release of the core, reduction in consumption of
precious materials, and so on.
 Nano- and microsized hollow particles are used for different purposes such as
microvessels, catalytic supports, adsorbents, lightweight structural materials
and thermal and electric insulators.

7. Different Shaped Nanoparticles
 Figure: Different core/shell nanoparticles:
i. spherical core/shell nanoparticles;
ii. hexagonal core/shell nanoparticles;
iii. multiple small core materials coated by single
shell material;
iv. nanomatryushka material;
v. movable core within hollow shell material.
 The properties of nanoparticles are not only
size dependent but are also linked with the
actual shape.
 For example, certain properties of magnetic
nanocrystals such as the blocking
temperature, magnetic saturation, and
permanent magnetization are all dependent
on particle size, but the coercivity of the
nanocrystals totally depends on the particle
shape because of surface anisotropy effects
Other nanoparticle physical and chemical properties
such as catalytic activity and selectivity, electrical and
optical properties, sensitivity to surface-enhanced
Raman scattering (SERS) and the plasmon resonance
and melting point are also all highly shape-dependent

8. Classes of Core/Shell Nanoparticles
 The core/shell type nanoparticles can be broadly
defined as comprising a core (inner material) and a
shell (outer layer material).
 These can consist of a wide range of different
combinations in close interaction, including
 inorganic/inorganic,
 inorganic/organic,
 organic/inorganic, and
 organic/organic materials.
 The choice of shell material of the core/shell
nanoparticle is generally strongly dependent on the
end application and use.
 Multiple core core/shell particles are formed when a
single shell material is coated onto many small core
particles together

9. Inorganic/Inorganic Core/Shell Nanoparticles
 Inorganic Metallic Shells such as Ni, Co, Pd, Pt and Cu are important for some
 specific applications in the field of catalysis, solar energy absorption, permanent magnetic
 properties, etc.
 Silica coating is the more basic and advantageous as compared with other inorganic (metal or metal oxide) or organic coatings as
it reduces the bulk conductivity and increases the suspension stability of the core particles. In addition, silica is the most
chemically inert material available; it can block the core surface without interfering in the redox .
 Gold coating on any particles enhances many physical properties, such as the chemical stability against redox reactions, the
biocompatibility, the bioaffinity through functionalization of amine/thiol terminal groups, and the optical properties (Presaa et al.,
2007).
 Semiconductor Core/Shell Nanoparticles- particles are used for medical or bioimaging purposes, enhancement of optical
properties, light-emitting devices, nonlinear optics, biological labeling, improving the efficiency of either solar cells or the storage
capacity of electronics devices, modern electronics field applications, catalysis, etc.

10. Inorganic/Organic Core/Shell Nanoparticles
 Inorganic/organic core/shell nanoparticles are made of metal, a metallic
compound, metal oxide, or a silica core with a polymer shell or a shell of any other high
density organic material.
 One example is the fact that the oxidation stability of the metal core is increased when otherwise the
surface atoms of the metal core can be oxidized to the metal oxide in a normal environment.
 The polymer-coated inorganic materials have a broad spectrum of applications, ranging from
catalysis to additives, pigments, paints, cosmetics, and inks.
 In many applications, the particles are coated to stabilize them in the suspension media, and the
stability of such a colloidal suspension depends mainly on the attractive and repulsive forces
between the particles (Bao et al., 2007).

11. Organic/Inorganic Core/Shell Nanoparticles
 The core of this particular class of core/shell nanoparticles is made of a polymer, and
different copolymers.
 The shell can also be made from different materials, such as metals, metal oxides or silica.
 The inorganic material, especially a metal oxide coating on an organic material, is beneficial
in several respects, such as increased strength of the overall material, resistance to oxidation,
thermal and colloidal stability, and abrasion resistance.
 At the same time, these particles also show polymeric properties such as excellent optical
properties, flexibility, and toughness, and in addition they can improve the brittleness of the
inorganic particles (Ammar et al., 2007).

12. Organic/Organic Core/Shell Nanoparticles
 In this category, both the core and shell particles are made of a
polymer or another organic material.
 These classes of particles are known as “smart particles” and have a wide range of
applications in different fields, such as drug delivery, biosensing, chemical separation,
biomaterials, and catalysis.
 The advantages of having a polymer coating on another polymer is to modify the
physical properties of the overall material, such as toughness or the glass transition
temperature.
 Polymer/polymer core/shell particles are also extensively used for controlled drug release
applications in in vivo systems because of their good biodegradable and drug
encapsulation property (Kayal and Ramanujan, 2010).

13. Approaches for Core/Shell Nanoparticle Synthesis
Approaches for nanomaterial synthesis can be broadly divided into two categories:
 The “top-down” approach often uses traditional workshop or microfabrication methods where
externally controlled tools are used to cut, mill, and shape materials into the desired shape and
order. The most common techniques are lithographic techniques (e.g., UV, electron or ion
beam),laser-beam processing, and
mechanical techniques (e.g., machining, grinding, and polishing).
 “Bottom-up” approaches, on the other hand, exploit the
chemical properties of the molecules to cause them to self-
assemble into some useful conformation. The most common bottom
-up approaches are chemical synthesis, chemical vapor deposition,
film deposition and growth etc.
 However, the bottom-up approach can produce much smaller sized particles and has the potential
to be more cost-effective in the future because of the advantages of absolute precision, complete
control over the process, and minimum energy loss compared with that of a topdown approach.

14. TECHNIQUES, CLASSIFICATION, AND MECHANISM OF CORE/SHELL
NANOPARTICLE SYNTHESIS
 In general, core/shell nanoparticles are synthesized using a two-step process, first synthesis of core and
second the synthesis of the shell.
 The synthesis techniques of core/shell nanoparticles can be classified into two types depending on the
availability of core particles:
 the core particles are synthesized and separately incorporated into the system with proper surface
modification for coating the shell material;
 the core particles are synthesized in situ, and this is followed by coating of the shell material.
 The basic advantage of external core synthesis is the fact that core particles are available in pure form
and hence there is less possibility of impurities on the core surface.
 Whereas, in in situ synthesis, the main problem is that some impurity from the reaction media may be
trapped between the core and shell layer.
 The most important step during synthesis of core/shell particles is to maintain uniform coating and to
control the shell thickness.
 Some of the various synthetic methods for core/ shell particles used by different research groups are
precipitation, polymerization, microemulsion, sol-gel condensation, layer by layer adsorption techniques
etc.

15. Core/Shell Nanoparticles Synthesis Schematic

16. ROLE OF NANOTECHNOLOGY IN OUR LIFE:
Nanotechnology has applications in all
convincible areas, and scientists /
researchers are finding newer
applications of the nano materials and
nano fabricated materials.
Currently nanotechnology is most
widely used in Cosmetics, Medicines/
Drugs, Defense, Fabrics, Energy and
Water purification, but in few years all
other domains will also be using
nanotechnology as potential tool
(Szostko et al., 2013).

17. Nanotechnology in Drugs(Cancer)
 Provide new options for drug delivery and drug therapies.
 Enable drugs to be delivered to precisely the right location in the body and
release drug doses on a predetermined schedule for optimal treatment.
 Attach the drug to a nanosized carrier.
 They become localized at the disease site, i.e cancer tumour.
 Then they release medicine that kills the tumour
 Current treatment is through radiotherapy or chemotherapy.
 Nanobots can clear the blockage in arteries.

18. Nanotechnology in Fabrics
 The properties of familiar materials are being changed by
manufacturers who are adding nano-sized components to
conventional materials to improve performance.
 For example, some clothing manufacturers are making water and
stain repellent clothing using nano-sized whiskers in the fabric
that cause water to bead up on the surface.
 In manufacturing bullet proof jackets
 Making spill & dirt resistant, antimicrobial, antibacterial fabrics.

19. Nanotechnology in Mobile
 Morph, a nanotechnology concept device
developed by Nokia Research Center (NRC) and
the University of Cambridge (UK).
 The Morph will be super hydrophobic making
it extremely dirt repellent.
 It will be able to charge itself from available light sources using
photovoltaic nanowire grass covering it's surface.
 Nanoscale electronics also allow stretching. Nokia envisage that a
nanoscale mesh of fibers will allow our mobile devices to be bent,
stretched and folded into any number of conceivable shapes.

20. Nanobots
 Close to the scale of 10-9.
 Largely in R&d phase .
 Nanobots of 1.5 nanometers across, capable
of counting specific molecules in a chemical sample.
 Since nanorobots would be microscopic in size, it would
probably be necessary for very large numbers of them to work
together to perform microscopic and macroscopic tasks.
 Capable of replication using environmental resources .
 Application:
 Detection of toxic components in
environment.
 In drug delivery.
 Biomedical instrumention.

21. Nanotechnology in Electronics
 Electrodes made from nanowires enable flat panel displays to be
flexible as well as thinner than current flat panel displays.
 Nanolithography is used for fabrication of chips.
 The transistors are made of nanowires, that are assembled on
glass or thin films of flexible plastic.
 E-paper, displays on sunglasses and
map on car windshields.

22. Nanotechnology in computers
 The silicon transistors in your computer may be replaced by transistors
based on carbon nanotubes.
 A carbon nanotube is a molecule in form of a hollow cylinder with a
diameter of around a nanometer which consists of pure carbon.
 Nanorods is a upcoming technology in the displays techniques due to
less consumption of electricity and less heat emission.
 Size of the microprocessors are reduced to greater extend.
 Researchers at North Carolina State University says that growing
arrays of magnetic nanoparticles, called nanodots.

23. Other uses
 Cutting tools made of nanocrystalline materials, such as tungsten carbide, tantalum carbide and
titanium carbide, are more wear and erosion-resistant, and last longer than their conventional
counterparts.
 Silver nanocrystals have been embedded in bandages to kill bacteria and prevent infection.
 Nanoparticulate-based synthetic bone
 Formed by manipulating calcium and phosphate at the molecular level.
 Aerogels lightest known solid due to good insulating properties is used in space suits and are
proposed to use in space craft.

24. Future Prospects
 The future generations of core/shell nanoparticles will exhibit many new properties that will surely result
in new applications with improved performance.
 Generally core/shell nanoparticles are well-known for better stability, for being able to protect the core
material from the surrounding environment, for improved physical and chemical properties, for improved
semiconductor properties, for easy biofunctionalization, etc.
 Most of the recent exciting discoveries show that there is tremendous scope in biomedical applications
such as controlled drug delivery and release, targeted drug delivery, bioimaging, cell leveling, biosensors,
diagnostics, immunoassays, and many more.
 In the near future, the development of new materials has the potential for improving the treatment of
cancer and many other life threatening diseases.
 Also, the future of nanotechnology could very well include the use of nanorobotics. These nanorobots
have the potential to take on human tasks as well as tasks that humans could never complete. The
rebuilding of the depleted ozone layer could potentially be able to be performed.

25. References:
1. Bao, Y., H. Calderon and K.M. Krishnan. 2007. Synthesis and characterization of magnetic-Optical
Co−Au core−shell nanoparticles. J. Phys. Chem. C. 111:1941-1944.
2. Kayal, S. and R.V. Ramanujan. 2010. Anti-cancer drug loaded Iron–Gold core–shell nanoparticles
(Fe@Au) for magnetic drug targeting. Journal of Nanoscience and Nanotechnology. 10:1-13.
3. Szostko, B.K., U. Wykowska, A. Basa and K.Szymański. 2013. Chemical preparation of core-shell
nanoparticles. NUKLEONIKA. 58:35-38.
4. Presaa, P.D.L., M. Multignera, M.P. Moralesb, T. Ruedaa, E. Fernández-Pinela and A. Hernandoa.
2007. Synthesis and characterization of FePt/Au core-shell nanoparticles. Proceedings of the
Joint European Magnetic Symposia. 209:8-39.
5. Ammar, M., F. Mazaleyrat, J.P. Bonnet, P. Audebert, A. Brosseau, G. Wang and Y. Champion. 2007.
Synthesis and characterization of core–shell structure silica-coated Fe29.5Ni70.5 nanoparticles.
Nanotechnology. 18:28.