The document discusses the definition, properties, and applications of nanofibers, which are fibers with diameters less than 50-500 nanometers. It details various techniques for preparing nanofibers such as electrospinning, self-assembly, and phase separation, along with their advantages and disadvantages. Additionally, it highlights the use of nanofibers in drug delivery, tissue engineering, cancer diagnosis, and air filtration.

1. NANOFIBERS AND ITS
RECENT TECHNOLOGIES
PRESENTED BY-
DEEPALI VERMA
M.PHARM(Phramaceutics), Semester-II
Dept. of Pharmaceutics, Amity Institute of Pharmacy
Amity University, Noida

2. INTRODUCTION
• Nanofibers are defined as fibers with diameters less
than 50-500 nanometers. National Science Foundation
(NSF) defines nanofibers as having at least one
dimension of 100 nanometer (nm) or less.
• There smaller size plays an important role in delivering
the drug to the appropriate site in the body.
• Either biodegradable or non-degradable materials can
be used to control whether drug release occurs via
diffusion alone or diffusion and scaffold degradation.
• Additionally, due to the flexibility in material selection a
number of drugs can be delivered including: antibiotics,
anticancer drugs, proteins, and DNA.

3. PROPERTIES OF NANOFIBERS
• Nanofibers exhibit low density, large surface area to mass,
diameter range (50 – 1000) nm, high pore volume, and tight
pore size make the nanofiber nonwoven appropriate for a
wide range of filtration applications.
• Physical properties- The differences in basic web properties
such as fiber area ,basis weights, thicknesses, permeability,
and strength. Electrospun Nanofibers have diameters that are
1to 2 orders of magnitude corresponding increase in fiber
surface area and decrease in basis weight.
• Filtration properties- Different fiber sizes can be made, some
as small as 40 nm. Fibers can be put on one side or on both
sides of a substrate. Nanofibers have been electrospun on to
a variety of substrates, including glass polyester , nylon, and
cellulose filter media substrates.

4. MATERIAL USED FOR PREPARATION OF
NANOFIBERS
• Natural Polymers include- collagen, cellulose, silk
fibroin, keratin, gelatin and polysaccharides such
as chitosan and alginate.(Using type I collagen
nanofibers produced via electrospinning, Shih et al.
found that the engineered collagen scaffold showed
an increase in cell adhesion and decrease in cell
migration with increasing fiber diameter.)

5.  Synthetic Polymers include- poly(lacticacid)(PLA),
polycaprolactone(PCL), polyurethane (PU), poly(la
ctic-co-glycolic acid)(PLGA), poly(3-
hydroxybutyrate-co-3-hydroxyvalerate)(PHBV),
and poly(ethylene-co-vinylacetate)(PEVA).
• PVA, PS, PAN, but also peptide amphiphiles .

6. PRINCIPLE OF NANOFIBRES
• Drug delivery with polymer nanofibers is based on the
principle that dissolution rate of a drug particulate
increases with increased surface area of both the drug
and the corresponding carrier if necessary.
• For controlled drug delivery, in addition to their large
surface area to volume ratio, polymer nanofibers also
have other additional advantages.
• For example, unlike common encapsulation involving,
Controlled delivery systems are used to improve the
therapeutic efficacy and safety of drugs by delivering
them to the site of action at a rate dictated by the need
of the physiological environment.

7. TECHNIQUES FOR PREPARING NANOFIBERS
METHOD PROCEDURE
ELECTROSPINNING -a high voltage is applied to a liquid polymer,
leading to the ejection of a continuous jet
strand from the spinneret towards a grounded
collector.
-The droplet then elongates to form a cone
known as “Taylor cone” and then is extruded
from the cone to form a fiber jet.
-The solvent in the jets is evaporated as the
fiber jets travel through the atmosphere and
solid polymer fibers are deposited on the
metal collector as nonwoven web
BUBBFIL SPINNING It is known that the increases in the molecular
weight and viscosity of polymers lead to higher
surface tension of their Taylor cone.Therefore,
higher electrostatic force is required for the
electrospinning to fabricate desired
nanofibers .

8. SELF-ASSEMBLY -It involves the spontaneous organization of
individual components into an ordered and
stable structure with preprogrammed non-
covalent bonds.
-Compared with electrospinning, self-assembly
can produce much thinner nanofibers only
several nanometers in diameter, but requires
much more complicated procedures and
extremely elaborate techniques.
PHASE SEPARATION /THERMAL INDUCED
/NON-SOLVENT-INDUCED PHASE SEPARATION
-Phase separation is a method frequently used
to prepare 3-D tissue-engineering scaffolds.
-Phase separation of a polymer solution can
produce a polymer-rich domain and a solvent-
rich domain, of which the morphology can be
fixed by quenching under low temperature.
-Removal of the solvent through freeze-drying
or extraction can produce porous polymer
scaffolds.

9. CENTRIFUGAL SPINNING -Centrifugal spinning, also called rotary
spinning or rotational jet spinning, has been
well developed. Since no high voltage is
required by the centrifugal spinning, the
system can alleviate safety-related concerns.
- In addition, centrifugal spinning can
remarkably improve the production efficiency
by increasing the rotational speed, allowing
the fast and large-scale fabrication of
nanofibers.
FREEZE-DRYING -(FD) can fabricate porous structures with
controllable sizes directly from polymers, such
as chitin, without structure-directing additives
or pretreatments needed also, no high
temperature and further leaching step are
required for the freeze-drying process .
-Starting with solution, emulsion, or
dispersion, freezing leads the solute or solids
to be excluded by ice front in the interstitial
spaces between ice crystals. Then porous
structures are created by the following
sublimation.

10. CHARACTERIZATION OF NANOFIBERS
NANOFIBE
RS
GEOMETRICAL
fiber diameter, diameter
distribution, fiber
orientation and fiber
morphology determined by
(SEM), (TEM) and (AFM)
PHYSICAL
Air and vapor transport
properties can be
measured by an apparatus
called dynamic moisture
vapor permeation cell
(DMPC)
CHEMICAL
(FTIR) ,(NMR),(DSC)
MECHANICAL
nanofibrous nonwoven
membrane can be performed
using conventional testing
techniques. When the
membranes are collected on a
static collector screen, no
anisotropy in the in-plane tensile
is reported.

11. APPLICATIONS OF NANOFIBERS
Tissue engineering
highly porous artificial
matrix is needed to
support and guide cell
growth and tissue
regeneration
Drug delivery
The criteria for an ideal
drug carrier include max.
effect upon delivery of the
drug to the target organ,
evasion of the immune
system of the body in the
process of reaching the
organ.
Cancer diagnosis
Liquid biopsy is an option
that, simply a blood draw
that contains circulating
tumor cells (CTCs) which
are shed into the
bloodstream from solid
tumors
Air filtration
Electrospun nanofibers are
useful for removing (VOC)
from the atmosphere
Medical Application
Nanofibers are also used
in drug and gene
delivery, artificial blood
vessels, artificial organs,
and medical facemasks.

12. RECENT TECHNIQUES FOR NANOFIBERS
• Several researchers have modified the basic setup
for solution electrospinning to increase the
productivity. The basic principle to obtain higher
productivity in solution electrospinning is based on
increasing the number of jets by adopting different
techniques. These techniques can be summarized
as: (a) Modifications on basic electrospinning
process for the production of nanofibres.(b) Melt
electrospinning setup for the production of
nanofibres.(c) Processes for the production of
nanofibres based on polymeric melt

13. Table 1. Modifications of basic electrospinning
process for the production of nanofibres
Process Features Advantages Disadvantages
Needless electrospinning
Polymer used: PEO
(Mw ¼ 600000),
Fibre diameter:
200–800 nm
Production rate:
12 times of the
conventional
electrospinning
Wider fibre
diameter
distribution
Bubble electrospinning
Polymers used: PVP
(Mw ¼ 40000 g/mol)
and PEO (Mw ¼
500000 g/mol)
Solution concentration for PVP ¼
30 wt% and
PEO ¼ 2 wt%
High production
rate, high efficiency,
free from clogging,
ease of operation,
simple process
and low cost
Solvent recovery
problem
Electroblowing
Polymer used: Hyaluronic
acid (HA) 2–3% (w/v); Fibre
diameter: 40–120 nm
High production
rate, and simple
process
Solvent
recovery
problem
Cylindrical porous hollow tube
Polymer used:
PVP (MW 360000);
Fibre diameter:
300–600 nm
High
productivity
Complex
design of the
equipmen

14. Table 2. Melt electrospinning setup for the
production of nanofibres
Process Features Advantages Disadvantages
Melt electrospinning
(Electrical heating)
Polymer used: PLA;
Avg. Fibre diameter:
800 nm
Simple setup,
solvent-free
approach
Mostly amorphous
fibre, thermal
degradation
Coaxial melt
electrospinning
Fabricated PCM based
nanofibre (sheath TiO2
and core octadecane);
Avg. Fibre diameter: 150
nm
One step process for
encapsulation;
Production of composite
nanofibres;
Suitable for wide range
of materials
Complex setup
Melt electrospinning
(heating gun)
Polymer used: PP and
PEG-b-PCL and PCL
blend; Fibre diameter:
35 1.7 mm
Production of blended
nanofibre
Coiling and buckling
instabilities of the jet
near to the collector
Melt electrospinning
(LASER heating)
Polymer used:
Polylactide; Avg. fibre
diameter: ~1 mm
High melting point;
Reduced thermal
degradation as local and
instantaneous
heating is possible
Amorphous fibres;
unstable fibre formation
with higher laser output

15. Table 3. Processes for the production of nanofibres
based on polymeric melt
Process Features Advantages Disadvantages
Die design for
providing airflow
in meltblowing by
Podgo´ rski
Polymer used: PP;
Avg. fibre diameter:
210 nm-37.5 mm
High production rate High variation of fibre
diameter
Meltblowing setup Polymer used:
polyesters, polyolefins
(PE and PP), PA, PU,
PVC, PVA and
ethylene vinyl acetate;
Avg. fibre diameter:
940nm along with
some microfibres
Favorable for many
polymers; High
production rate
Complex process

16. REFERENCES
• Rajkishore Nayak, Rajiv Padhye,” Recent advances in
nanofibre fabrication M Techniques , Textile Research Journal
82(2) 129–147,2011
• Ramakrishna S. An introduction to electrospinning and
nanofibers. World Scientific Pub Co Inc, 2005.
• Ying Zhao,Yihui Qiu, Preparation of Nanofibers with
Renewable Polymers and Their Application in Wound
Dressing, International Journal of Polymer Science
Volume 2016 (2016)
• O. Ayaz, N. Ucar, E. Bahar, et al., “Properties of composite
nanofiber produced by single and coaxial nozzle method used
for electrospinning technique,” International Journal of
Chemical and Biological Engineering, vol. 6, pp. 52–56, 2012.
• SeeramRamakrishna,KazutoshiFujihara,Electrospun
nanofibers: solving global issues, Volume 9, Issue 3, March
2006, Pages 40–50