electrospun nanofibres

1. Submitted by:
Nikita Gupta
Mtech-NST
01140801014

2. Introduction
 Nanofabrics are composed of non-woven Nano fibers.
 Nano fibers are created by a process called electrospinning.
 Electrospinning is a major way to engineer (without self-assembly)
nanostructures that vary in:
 Fiber Diameter
 Mesh Size
 Porosity
 Texture
 Pattern Formation
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Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006. http://en.wikipedia.org/wiki/File:Taylor_cone_photo.jp

3. Electrospinning Setup
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1. A high voltage power supply (normally
working in a range between 10 and 30kV);
2. A polymer reservoir that can maintain a
constant flow rate of solution, commonly a
syringe connected to either a mechanical or a
pneumatic syringe pump;
3. A conductive dispensing needle as polymer
source connected to the high voltage power
supply;
4. A conductive substrate, normally grounded,
which serves as a collector for the
electrospun fibers.

4. Electrospinning – Parameters
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 Polymer precursor material.
 Solvent and solution additives.
 Polymer concentration.
 Needle-to-collector distance.
 Voltage.
 Flow rate.
10kV 15kV 20kV
To optimize material
properties, fiber
thickness, homogeneity,
density, and distribution.

5. Electrospinning - Procedure
 An electrostatic potential is applied between a spinneret and a collector
 A fluid is slowly pumped through the spinneret.
 The fluid is usually a solution where the solvent can evaporate during the
spinning.
 The droplet is held by its own surface tension at the spinneret tip, until it gets
electrostatically charged.
 The polymer fluid assumes a conical shape (Taylor cone).
 When the surface tension of the fluid is overcome, the droplet becomes unstable,
and a liquid jet is ejected
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Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.

6. Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.
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7. Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.
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8. Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.
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9. Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.
Types of Solvent Stream Ejections
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10. Electrospinning Polymers
 The small size between the fibers allows the capture of particles in the 100- to 300-
nanometer range
 That is the same size of viruses and bacteria
 Used as air-filter: Airplanes, office, etc.
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Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.
Polymer Solvent Concentration Potential Application
Nylon 6,6 Formic Acid 10 wt% Protective Clothing
Polyurethanes Dimethylformamide 10 wt% Protective Clothing
Polycarbonate Dichloromethane 15 wt% Sensor, Filter
Polylactic Acid Dichloromethane 14 wt% Drug Delivery System

11. Applications
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Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.

12. Applications
Ultrafiltration in water treatment
 High flux, low-fouling membrane
 The top layer provides the actual filtration, and the middle and bottom
layer provide sting support and are very porous
 Increased efficiency
 Able to filter without top layer.
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Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006. Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.

13. Recent Research on Electrospinning
13
Surface-functionalized Elecrospun
Nanofibers for Tissue Engineering and
Drug Delivery
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14. Electrospun Nanofibers
 High surface area to volume ratio
 Versatile method for preparing nanofibrous meshes
 Potential applications:
 Biomedical devices
 Tissue engineering scaffolds
 Drug delivery carriers
 Done through Surface Modification
 Plasma treatment
 Wet chemical method
 Surface graft polymerization
 Co-electrospinning of surface active agents and polymers
 Creates bio-modulating microenvironments to contacting cells and tissues
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"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."

15. Surface Modification Techniques
 Synthetic polymers vs. natural polymers
a. Synthetic: easier processing for electrospinning and more controllable
nanofibrous morphology
b. Natural: difficult to directly process into nanofibers because of unstable
nature and weak mechanical properties
 Natural polymers can be immobilized onto the surface of synthetic polymers
without compromising bulk properties
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"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."
http://www.animate4.com/nanotech/nanotechnology/nanomedicine/nano/nanoscale/nanotech-
nanotechnology-nano-nanomedicine-moleculare-nanotech-nanoscale.jpg

16. Modification – Plasma Treatment
 Changes the surface chemical composition
 Selection of plasma source – introduce diverse functional groups on surface
a. Plasma treatments with oxygen, ammonia, or air – generates carboxyl
groups or amine groups
b. Air or argon treatments
 When nanofibers were soaked in a simulated body solution – calcium
mineralization occurred on surface
a. Improved wettability
b. Potential with bone grafts
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"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."
http://www.deviceda
ily.com/wp-
content/uploads/2008
/11/fortross-02.jpg

17. Modification – Wet Chemical Method
 Films and scaffolds under acidic or basic conditions – modify surface
wettability
 Plasma treatment can not modify surface of nanofibers deep in the mesh
 Wet chemical etching methods can modify thick meshes
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"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."

18. Modification – Surface Graft Polymerization
 Synthetic biodegradable polymers retain hydrophobic surface – need hydrophilic
surface modification for desired response
 Introduce multi-functional groups on the surface
 Enhanced cell adhesion, proliferation, and differentiation
 Initiated with plasma and UV radiation treatment to generate free radicals for
polymerization
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"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."

19. Modification – Co-electrospinning
 Nanoparticles and functional polymer segments can be directly
exposed on surface of nanofibers
 Co-electrospinning with bulk polymers
 Any combination of electrospinnable polymer and polymer
conjugate can be used
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"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."

20. Target Molecule Loading on Surface
 Simple physical adsorbtion
 Nanopoarticle assembly on surface
 Layer by layer multilayer assembly
 Chemical immobilization
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"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."

21. 11/21/2015 21

22. Applications – Drug Delivery
 Superior adhesiveness to biological surfaces
 Variety of structures containing drug molecules
 Drug release mechanism – polymer degradation and diffusion pathway
 Can tailor drug release profiles by varying polymer properties, surface coating,
combination of polymers
 Has been successful in laboratory trials – controlled topical release
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"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery."

23. Applications – Tissue Engineering
 Various cells cultivated on nanofibrous meshes
 Embryonic stem cells, mesenchymal stem cells
 Better than other tissue engineering methods
 Coronary artery cells
 Collagen
 Limited to in vitro studies because cells could not be loaded within the
nanofibrous meshes in large quantities
 3D nanofibrous scaffolds
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"Surface-functionalized Electrospun Nanofibers for Tissue Engineering and Drug Delivery." http://pcsl.mit.edu/images/nano.jpg

24. Improvements and Further Research
 Develop more precise electrospinning techniques
 Mechanisms of electrospinning
 Growth rates
 Bending Instability
 Producing nanofabrics with specific mechanical
properties.
 Creating 3-dimensional shapes
 Capable of being used in controlled release of drugs.
11/21/2015 24
Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.

25. Improvements and Further Research
 Optimization of parameters
 Intrinsic properties of solution
 Polarity, surface tension of solvent
 Controlling nanofiber alignment
 Electric field
 Modifying type of collector
 Better control of fiber alignment
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"Electrospin Nanofibers for Neural Tissue Engineering."
http://www.rsc.org/ejga/NR/2010/b9nr00243j-ga.gif

26. Improvements and Further Research
 Reduce Cost of Production
 Make economically viable
 Increase production rate
 Incorporate the use of an array of
spinnerets
 Safety
 Solvents
 Dangerous to health and environment
 Polymers 11/21/2015 26
Burger, Christian, et. al. Nanofibrous Materials and Their Applications. 2006.

27. References
 Burger, Christian, Benjamin S. Hsiao, and Benjamin Chu. "Nanofibrous Material and
Their Applications." Review. 25 Apr. 2006. Web. 14 Feb. 2010.
 Hunley, Matthew T., and Timothy E. Long. "Electrospinning Functional Nanoscale
Fibers: a Perspective for the Future." Polymer International 57 (2008): 385-89. Web. 7
Mar. 2010.
 Theron, J. P., J. H. Knoetze, R. D. Sanderson, R. Hunter, K. Mequanint, T. Franz, P.
Zilla, and D. Bezuidenhout. "Modification, Crosslinking and Reactive Electrospinning of
a Thermoplastic Medical Polyurethane for Vascular Graft Applications." Acta
Biomaterialia (2010). 27 Jan. 2010. Web. 05 Feb. 2010.
 Xie, Jingwei, Matthew R. MacEwan, Andrea G. Schwartz, and Younan Xia. "Electrospin
Nanofibers for Neural Tissue Engineering." Nanoscale 2 (2010): 35-44. Print.
 Yoo, Hyuk S., Taek G. Kim, and Tae G. Park. "Surface-functionalized Electrospun
Nanofibers for Tissue Engineering and Drug Delivery." Advanced Drug Delivery Reviews
61 (2009): 1033-042. Print. 11/21/2015 27

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Thank you!!