Today we shall discuss on polymeric nanomaterials
and devices, mostly biomedical devices.
Now, you know today nanotechnology has come
to the forefront everybody has got interest
in this nanotechnology development of various
devices. Using nano materials, which involves
nano science, you know what is nano science?
Science of small dimension, nano dimension,
so that nano materials scale science has been
devoted to design and construction of functional
structures and the replacement for suitable
devices.
And that is in biomedical field that nanotechnology
is being used for treatment for diagnosis
for monitoring and control.
This nanomedicine devices contains nanoparticles,
nano machines, nano fibers and sensors. Nanoparticles
you know there are various techniques 
to form this nanopaarticles or nanomaterials.
There are two major approaches; bottom up
approach and top down approach. So, if you
can make some materials made of these nanoparticles,
these particles in nanodimension say might
be below 100 nano meter or 200 nanometer like
that. They show some unusual properties. You
know gold its color is yellow when it has
been broken down to nano particles, gold nano
particles its color changes from yellow to
blue to green to purple to red and their properties
are different.
Now, you have seen in case of carbon black
carbon black there are various gates of carbon
black of which one gate is channel black or
sometimes hardness black. Channel black they
are available in small particle size hardness
black hardness carbon black is available,
it is also available in small particle size
2 into 20, 30, 40, 50, 100, 200, nanometer
dimension when those particles are used as
filler in our compounds we get very good reinforcement
properties, reinforcing properties, re-improved
strength of the composite.
If I mention one aspect say in homeopathic
treatment homeopathic medicine, you know homeopathic
medicine that is the strength of the homeopathic
medicine depends on dilusion. Higher dilusion
is a stronger mission medicine, lower medicine
means concentrated solutions or higher concentration
solutions of higher concentration are little
lower strength. What is the why this happens?
You know these homeopathic medicines these
are made from chemical products either synthetic
products or herbal products herbal base.
In all the cases some concentrated medicine
is taken and it is diluted and there is a
process of dilution process of dilution. Now,
simply you add that medicine in a solvent
sew water and you get the dilution norm there
is certain process they have certain process
they give some mechanical vibration and they
get higher dilution homeopathic medicines
and that becomes a stronger medicine. Now,
in that stronger dilution homeopathic medicine
with the help of available instrumental facilities
the presence of that chemical compounds of
that medicine would not be detected, but still
it is stronger medicine.
In case of higher concentration medicines
lower potency there sometimes one can detect
the presence of those chemical compounds,
why this happens? Now, my concept is there
might be some sort of the separation of the
molecules or dispersion or solution of those
medicine medical compounds in molecular level.
In aggregates they function in one way in
dispersed condition in molecular level they
function in other way that might be the reason,
but that research has not been done we do
not know, but today these nanomaterials or
nanotechnology indicates that by virtue of
the small dimension as well as their high
surface energy they prone to be to form aggregate
agglomerates.
If you can break the aggregates then we can
get the dispersion in smaller dimension probably
we can exploit the real properties at the
molecular level. So, there are certain properties
at the molecular level the aggregates aggregates
of those materials may not perform the same
level of properties that we have visualized
in some cases. You see the color of gold changes
from lum to these nano-particles their properties
are also changes. So, this concept is being
utilized in various fields for various purposes.
We are all seen biomedical field people are
trying to utilize this nanotechnology for
treatment for diagnosis for machines micro
machines etcetera nano machines as well as
in censors. So, I will give you some exposure
to you this thing those materials and some
devices.
So, the term usually applies to living or
processed tissues materials it usually applies
to living or processed tissues or the materials
used to reproduce the function of living tissue
in conjunction with them. Simply it is a material
intended to interact with biological system.
Bio material meant for using in some biomedical
device that is used in place of living tissue,
so that that device can function like that
of the host tissue. So, it should be biocompatible
it should be it should be non toxic it should
be bio acceptable and it should perform the
real function what you want.
Now, what are those materials for used in
implant devices biomedical implant devices?
We can use polymers, we can use ceramics,
we can use metals. Now, you have some exposure
to polymers names of various polymers various
categories of polymers you have seen addition
chain polymers, condensation polymers. You
know their structures addition chain polymers
exclusively condensed carbon chain structures
condensation chain polymers content carbon
as well as other hetero atoms in its backbone
structure.
Condensation polymers are more pooler than
addition chain polymers right. And looking
at the structure of a polymer you can predict
its properties, you can predict its inertness
its reactivity say for example, you want to
make a device you want to some article of
course, if you know the chemical formula chemical
structure chemical nature of the polymer you
can predict whether it will be it will remain
stable or it will be unstable in the environment
or within a living system.
So, polyethylene if I talk about polyethylene
polyethylene is not degraded by environment
it is not degradable by environment ambient
environment, get it if it is exposed to ambient
environment say exposing to sunlight exposing
to humidity exposing to rain exposing to air
etcetera all these things. So, polyethylene
is not degraded that is why polyethylene is
causing lot of problems nuisance in the environment.
Because it is a stable polymer having carbon
carbon bond and carbon hydrogen bonds, where
as a polyester polyester which contains carbon
carbon bonds as well as carbon oxygen bond
and carbon hydrogen bonds.
Now, this carbon oxygen bonds it is located
in the ester group you know this ester group
is degradable hydrolytically degradable in
presence of acid or alkali it can break. So,
it can be degraded little naturally occurring
polymers you know their structures formulas
chemical composition. Naturally occurring
polymers contain carbon hydrogen nitrogen
oxygen sulphur all these things isn’t it?
Majority of them except natural rubber majority
of them contain such atoms as well as bonds
are present. And those are actually those
are easily degraded by nature oxidity degradation
thermo oxidity degradation microbial degradation
all these degradation occurs there. But if
we put these polymers in living system which
contain biological field, the p h sometimes
is around 7.4 or within the stomach, p h may
be little lower or higher. So, in those environments
if polymers are put over there if the polymers
get hydrolyzed within the living system then
the stability of the polymer will be at stake.
Now, there are certain requirements in the
biomedical field that we need to degrade the
polymer say absorbable future you know suture
thread suture thread or biodegradable suture
absorbable suture means when that suture threads
are used for stitching purpose after surgery
or for the purpose of healing a wound. So,
it comes in contact with the body fluid. Now,
if it is non-absorbable, non-biodegradable
suture after wound healing there is a necessity
of removal of the suture thread from the body
that is a painful. Now, if there is absorbable
suture which will be slowly absorbed within
the body fluid and the degradation products
will be excreted from the body slowly then
that removable tape can be avoided.
So, say internal operation, suppose within
the body after operation it is actually closed
and stitched, now that is done by tissue adhesive
or suture. Now, if the suture is used again
if it is non-absorbable then it is to be again
removed after the wound is healed. So, for
those purpose we have to see what polymer
we have to select depending on the requirement
there are certain requirements say tissue
engineering scaffold for hard tissue replacement
say total hip joint replacement or knee replacement
or finger replacement, finger joint replacement
anything, for hard tissue means bone bone
replacement.
What we would do we make a we make scaffold
from calcium synthetic calcium hydroxyapatite,
you know calcium hydroxyapatite you have heard
this name calcium hydroxyl. It is a bone mineral
it is present in bone normally bone, now if
a skeleton or scaffold is made porous. Scaffold
is made from this thing or a composite is
made from this calcium hydroxyapatite or bio-glass
or calcium phosphate using collagen as the
matrix.
This is the reinforcement, this is the matrix,
so a composite will be formed a composite,
now that composite can be used for replacement
of bones or else we can make scaffold from
calcium hydro porous scaffold calcium hydroxyapatite.
Today people are making bio ceramics porous
bio ceramics, now after replacement. What
happens, native bone formation will be there
means it will help ostio conductivity. It
will help in ostio conductivity and native
bone will be formed and slowly those pores
will be filled, if you take some composite
made from collagen calcium hydroxy calcium
phosphate or calcium phosphate or some other
polymer, say polyhydroxy butyrate 
polyhydroxy butyrate or valarate polyhydroxy
or polyhydroxy valarate.
These are actually bacterial polysaccharide
bacterial polysaccharide produced by bacteria
it is a polymer polysaccharide polymer. This
is a biodegradable polymer or chitin or chitosan
or chitosan. Now, these can be used as matrix
with calcium phosphate or calcium hydroxyapatite
or even a bioactive glass I mentioned earlier
bioactive glass. So, what will happen these
polysaccharides or collagen or or other bio-degradable
say polylactic acid polyglycolic acid polylactic
co glycolic acid co polymer. Now, these biodegradable
polymers with this calcium phosphate or bioactive
materials or calcium hydroxyapatite that will
form a composite. That can used for replacement
of bone slowly these polymers will degrade
within the body creates some space in those
spaces the native bone tissue will be formed.
So, after surgery say after 6 months of surgery
or 5 months of surgery, one can find that
the artificial part which was replaced which
replaced the which was put inside the body
that is no longer present there is almost
original bone, native bone has been formed
there. So, that can help in healing of some
damage bone damage or affected or diseased
bone these things can be replaced there some
people are using some nanomaterials. Yesterday
there was a lecture in our centre they have
shown some bio ceramic nano bioceramic made
from nano cellulose and nano bioceramic particles.
So, we can use this polymers, polymers which
must be compatible with the host system that
means we will try to find we must try to find
out some similarity of this polymers with
the polymers present in the host tissue. Yes
please, no if it is biodegradable that polymer
will degrade slowly some space will be created
and there native bone tissue formation starts
and it will be filled by the native bone.
No catalyst, so this is 
the by your normal physiological system physiological
process you see if there is some injury on
a tissue if there is no external attack by
external agency there will be normal healing
regeneration of tissues by the its own system
do not go to that complications at this stage,
but it occurs certain you it has been found
that at the age of 90 years at the age of
90 years fractured bone is repaired. How it
happens? These, it happens due to falling
in the bathroom at the old age people gets
their bone fractured after plastering and
some treatment it is cured. So, it is not
that, so long the system is living.
There is all the moment there is tissue growth
tissue formation either bone tissue or soft
tissue you cannot say at the old age this
tissue formation will be totally stopped.
No, it is the rate may be slower rate may
be slower the situation may be little difficult,
but it is there. So, what you see polymers
are used in biomedical field it is again a
vast subject it is a vast subject I am giving
a little exposure introduction to you. So,
that if anywhere it is necessary you can explore
then ceramics are also used metals are also
used titanium titanium, annadium, aluminium
alloy these are used for total heal processes
today ceramics are also used.
Now, since you are material scientists you
should not keep aside the concept of bonding
always you should think in terms of chemical
bonding present in a in those materials and
devices. Primary bonding and secondary bonding,
nature of bonding nature of primary bonding
nature of secondary bonding and total quantity
of primary and secondary bonding present so
you should take care of that properties requirement
biocompatibility.
That means the external or foreign system
foreign body should be acceptable or should
be accepted without any hazard, without any
toxic effect in the body. If it is not if
there is cell proliferation cell growth tissue
growth say all those things in presence of
foreign bodies, then we can say this material
is biocompatible. There is methods of testing
also to test the biocompatibility of a material
be it polymer be it ceramic be it metal there
are tests are available standard tests methods
are there.
That means what we do what is normally done
in order to test the biocompatibility take
a specimen on the material put in a culture
media containing certain cells if in presence
of that specimen, cells continue to grow or
proliferate populate. You say there is no
toxic effect so you can say in one way it
is biocompatible, but this is invivo test.
So, by test we can say whether it is biocompatible
or not also this is not complete.
You have to go through also invivo test you
have to put that specimen inside a living
system animals you have to go to for animal
testing. Means you put this thing in the animal
you see the heart beat behavior change of
high beats behavior and the change of body
temperature etcetera. All these things if
those are those remains unaffected it can
be set fight that yes it is acceptable by
the living system biological system biocompatible.
So, this is a second stage second step success,
third step success is if you want to apply
in humans.
Then in the third step it should be applied
in humans system again some monitoring system
should be there through some monitoring system
if there is no adverse effect. By putting
this thing inside the body then it can be
recommended as suitable biocompatible material
biocompatible device which can be used their
physical chemical properties, physical properties
as well as chemical properties you know. What
are the physical properties you know, chemical
properties? You know mechanical properties
strength aspect tensile strength modulus long
break hardness their compressions rate.
And sometimes dynamic properties dynamic mechanical
properties etcetera then thermal stability
also has to be considered at body temperature
at body temperature whether those materials
and devices are stable or not sometimes some
materials need electrical conduction. So,
electrical properties as well as optical properties
and stability and degradation how long they
are stable if there is slow degradation in
presence of body fluid say you have to test
it through simulated body fluid and you have
to see if there is any degradation. If you
take out the specimen you have to analyze
specimen and you have to analyze the surrounding
medium say fluid or tissue if there is any
degradation product or not if there is some
degradation product you have to see what ere
the degradation products are those toxic or
not those things have to evaluated for this
materials.
So, acceptance of an implant by surrounding
tissues and by the body as a whole can tell
you about the biocompatibility. The implant
should be compatible with tissues in mechanical,
chemical, surface an pharmacological properties.
Simply it is the ability of the implant material
to perform with an appropriate host response
in a specific application host response response
of the host after accepting after putting.
This thing behavior of the host mechanical
properties say cortical bone cancerous bone
enamel dentine materials. The modulus, then
modulus tensile strength, then mechanical
properties of soft tissues those are the mechanical
properties of hard tissues. These are the
mechanical properties of soft tissues cartilage,
ligament, tendon, skin, arterial tissue in
two directions intraocular lens. So, you see
the requirement of this indicates the requirement
of mechanical properties of the materials
which are to be used of such biomedical devices.
Now, there one can apply the nanotechnology
in the fabrication during the fabrication
of such devices.
So you see this is the tensile strength and
this is the modulus tensile strength, this
is wrong actually this should be Giga Pascal
this should be Giga Pascal not mega Pascal
modulus is higher anyway.
Then mechanical properties of typical ceramic
and metallic biomaterials you can compare
the tensile strength and modulus of some metals
and ceramics. You compare metals are stronger
tensile strengths are more in case of metals
and hydroxyapatite you see. Hydroxyapatite
this is a bone mineral and alumina very hard
ceramics alumina zirconia all the hard ceramics,
so their properties are higher than those
of hydroxyapatite. Here is a problem, if you
want to replace any part of the body with
such foreign materials like metals and ceramics
properties matching is very difficult to obtain
isn’t it look at the properties they are
very strong, so there is a mismatch on this
properties.
Then you look at the polymers the mechanical
properties say modulus and tensile strength
these properties are close to those of soft
tissues. And mechanical properties of some
composites can be brought very close to those
of hard tissues that is possible with polymers.
That can be tailored again following this
nanotechnology. Nanotechnology I mean you
have to follow certain process, so that nanodimensional
enforcement is possible to form say think
of cellulose cotton if you want to make nano
nanodimensional cotton fiber.
How you can make you know cotton contains
cellulose molecules cotton. In this cellulse
molecules, in the cotton fiber highly crystalline
and that is the reason for its insolubility
infusibility cotton, which contain an hydro
glucose unit rings an hydro glucose unit an
hydro glucose unit those an hydro glucose
units unite one after the other to form a
cellulose molecule.
There is extensive intermolecular hydrogen
bonding between cellulose molecules through
hydroxyl group to primary hydroxyl sorry,
1 primary hydroxyl group and 2 secondary hydroxyl
groups are there by virtue of that hydrogen
bonding between those hydrox hydroxyl groups.
There is intermolecular hydrogen bonds present
in cotton cellulose cellulosic materials.
If you want to make, if you want to make nano
fiber out of this cotton fiber it is difficult.
Difficult in the sense it is not soluble in
the solvent, it is no feasible, you have to
do now if you can. Find I technique to break
the hydrogen bonds intermolecular hydrogen
bonds. Then you can separate the cellulose
molecules means your cellulose molecules from
each other. Then only it is possible to form
nano cellulosic fiber. Once this nano cellulosic
fibers are formed you know this hydroxyl group
will be exposed or opened hydrogen bonds will
be broken again there is every tendency of
reformation of hydrogen bonds there is the
problem, that is when you make some nano particles
a partical in nano dimension eventually there
will be recombination to form the aggregate
that means it becomes difficult to maintain
the nano dimension.
So, if it is possible to prepare this nano
unit in C 2 in C 2 that means if immediately
some some your third things thing comes between
2 units nano units, then that will prevent
their combination recombination. Then only
you can get dispersion of nano units in a
matrix. So, in case of celluloids say what
you can do you have to break the hydrogen
bonds. How to break the hydrogen bonds? There
are two ways thermal and chemical or else,
if you apply thermal energy that should be
in such a mount.
So, that it only reaches the energy of this
that hydrogen bond which can break isn’t
it? You can use some chemical energy some
chemical materials chemical compound chemical
agent. If it can provide that energy close
to that of hydrogen bond breaking energy then
that can break and eventually you have to
disperse those nano fibers preventing recombination.
So, we can imagine one thing a cotton fiber
or any other natural fiber that is a bundle
of fibrils a fiber is bundle of fibrils fibrils
are having smaller diameter than fiber. A
fiber can be considered as a bundle of fibrils,
so your job would be to separate those fibrils
from a fiber by breaking intermolecular hydrogen
bonds.
Now, again each fibril can have large number
of cellulose molecules a bundle so fibrils
can be bundle of cellulose molecules. And
fiber is bundle of fibrils, so in each step
you have to break the hydrogen bonds. Now,
there is a technique called steam explosion
technique. what is that steam explosion technique?
You take this fibers in an auto, you put these
fibers in water or take a dispersion of this
fibers in water take that dispersion in an
auto club close, the auto club. Start heating
means, if it is electrically heated put on
the switch, so it will increase the temperature.
So, that water will vaporize and form steam
so if you go on increasing the temperature.
So, you will have steam at higher temperature
a superheated steam will be there, so in that
condition what will happen water molecules
will go in between those fibrils as well in
between those cellulose molecules and the
energy available over there is sufficient
to break those hydrogen bonds. So, water molecule
can be penetrated in between those fibrils
and cellulose molecules then what you have
to do suddenly open the auto is at high pressure
sudden go for sudden release of pressure,
what will happen? So, inside the fiber there
are water molecules in between fibrils and
cellulose molecules so on sudden release of
pressure there will be some bursting effect.
So, water molecules are water molecules in
between the fibrils those are under pressure,
so outside that when the pressure is released,
so that fiber will be burst out. Fibrils will
be separated fibers will be separated, this
is one way and that will be dispersed water
is there. So, then that will those cellulose
molecules will try to form hydrogen bond with
water molecules not with another cellulose
molecule, so intermolecular hydrogen bonds
will be broken, but intermolecular cellular
hydrogen bonds will be broken. But some hydrogen
bonds between cellulose and water will be
formed is it clear. So, what will get we can
get dispersion of nano cellulose fibers in
water this is one way in another way.
You can go for ultra ultrasound treatment
if you expose this system that slurry or dispersion
to ultrasonic ultrasonic your energy environment
by the sonication the hydrogen bonds can be
broken depends on what frequency of ultrasonic
energy at what frequency you are using you
are applying. So this way you can make nano
fibers, so these techniques are been followed
wherever one technique is suitable you selection
of any technique is up to you which you can
really handle. So, this way one can get nano
fibers, so here you see if you can make fibers
from these polymers in nano dimensions or
killers say clay nano clay etcetera.
So, if you can disperse these polymers you
can make nano devices nano composite devices
for biomedical application and there will
be intimate contact between the fiber and
the matrix if intimate contact between the
fiber and the matrix. Then only you can get
the nano effect, what happens in macroscopic
composites? In macroscopic composites this
reinforcement either in the particular form
or in the fiber form those are in bigger dimension
bigger dimension.
So, total interface area between the reinforcement
and the matrix less there, now if you think
of say five gram of material if you can break
it to nano dimension you calculate you can
calculate the total amount of surface area
of the particles available will be available
in the nano dimension. Say 10 nanometer suppose
10 nanometers 5 gram of 10 nanometers of a
material you can calculate the surface area
considering assuming it as spherical particle.
Then you compare this total surface area with
that of 40 gram of the same material having
say micro dimension you will find that the
surface area available from that nano the
smaller amount of that nano material will
be higher than that one. So, what it is giving
it is giving that more surface or interface
per contact between the matrix and the fiber.
So, you can get fruitfully the nano effect
nano composite, so this is the concept only
thing you have to make the experimental you
have to develop the experimental set up then
only we can get the success otherwise it is
difficult.
Implant devices, scaffolds for tissue engineering.
Now, to talk about scaffolds, now, today people
are making scaffolds from nano fibers nano
fibers, people are making silk nano fibers
silk is a natural fiber now that is actually
dissolved in a suitable solvent. Then by nano
spinning process or by electro spinning process,
so that solution that solution of that silk
in a suitable solvent is spun through nano
opening. Then electric field is applied across
this spun fiber say fibers are drawn fibers
filaments are coming down from the nano that
spinneret and some electric field is applied.
So, at that high electric field the fiber
dimension becomes very thin that helps actually
that your application of electric field at
high voltage helps in getting very thin fiber.
So, people are making conducting polymer nano
fibers by that technique. I have seen that
setup that device people are making nano conducting
polymer nano fiber people are making are making
silk nano fibers collagen nano fibers protein
nano fibers by this technique.
And those are used for making scaffolds those
scaffolds are used for tissue engineering
that means scaffold is a support scaffold
is a support on which tissues are grown cells
are grown to get a proper tissue in a proper
cell. And dimension in the last class. I I
was telling mio cardial tissue construction
by cells engineering mio cardial tissue construction
by cells. Engineering without using any scaffold
with the help of that stimuli responsive polymer
or thermo responsive polymer, but you can
use some scaffold for tissue engineering.
So, that scaffold can be porous support of
course, there should be porous support or
a network hydrogel or gel materials where
ample space is available for tissue growth
tissue accommodation there, ultimately if
the scaffold is biodegradable, then by slow
biodegradation. Ultimately we can get a native
tissue hydrogels in regenerative medicine
in regenerated medicine bones and joints vascular
grafts heart valves tendon and muscle drug
delivery devices contact lens sutures.
So, many large number of applications can
be mentioned polymers in health care. I I
have told many things, now look the examples
of polymers polymethyl methacrylate. This
acrylate polymers this acrylic polymers, because
of their excellent refractive index.
Those are used in optical devices, so contact
lens rigid contact lens earlier for rigid
contact lens manufacture or preparation PMMA
was the ideal material, but it created certain
problems of hydrophobicity hydrophobicity
and lack of porousity, all these things media
properties because it should permit water
molecules sodium chloride and other things.
So, today today’s optical or contact lens
is being made of these acrylate polymers,
but not PMMA or a copolymer with other monomer
with methyl methacrylate have you heard this
name 
polyhema polyhydroxy methyl methacrylate you
know methyl methacrylate.
This is this is methyl methacrylate in case
of polyhema this group is replaced by hydrox
ethyl group hydrox ethyl group now you see
by placing that hydroxyl ethyl group it increases
the balkanization of this portion CH2 CH2
group additional carbon that regulates the
hydrophilicity and hydrophobicity as well
as tracking OG the molecular tracking. So,
what we need we need some space to passage
for the passage of this water and other salts,
so things tears suppose tears not only that
it should maintain a proper flexibility or
it should be it should remain moist all the
time.
It should not get dry or if it is hydrophobic
in nature if it cannot invite water molecules
it cannot like water molecules. Then that
will cause irritation that is why today co
polymers I do not know the composition this
is not disclosed, but copolymer of Polyhema
Hema with MMA MMA hema or sometimes in place
of hydroxyl ethyl group. There may be other
alkali group, also then polyamides poly lactic
acid PVC PVC for bag for blood bag blood bag
you have seen blood bag for collection of
blood that is made of PVC.
Although it is banned today that is flexible
PVC plasticized PVC it is banned globally,
but in India nobody bothers, so we are using
this plasticized PVC bags. The problem is
it gives a life to the blood to say for 30
days only at 4 degree Celsius 30 days life
is available again. It has been found within
30 days there is rupture of your blood components
due to the presence of plasticized blood components
over there, now plasticizers are ester plasticizers.
Now, those ester plasticizers are hydrolyzed
to form monoester those monoesters actually
come out from this PVC plasticized PVC film
and mix with the blood that contaminates.
The blood that it brings some toxicity to
the blood that is why this plasticized PVC
is banned still people are using in our lab
we have developed some PVC that film for blood
bag without using any plasticizer catheters.
You have seen catheters flexible tubes soft
tubes transparent tubes IVC stem IVC stem
those are made of PVC vascular prostheses
vascular prostheses. You see mess or leads
or fabrics made of polyethylene triethylic
fiber this is called dacron fiber dacron dacron
fiber dacron fiber trade name of polyethylene
tri ethylyte dacron fiber that is used for
making vascular. That means your veins or
arteries along with some fluorinated polymer
fiber fluoro polymer fibers.
If anybody of you is interested literature
is available you can go through, you can see
there is a course on biomaterials you can
take that course also to get in details polyurethane.
Although, these polyurethanes are made from
what polyurethanes are di isocyanides and
diol. You know iso cyanides are highly toxic.
Now, once this iso cyanide groups react with
hydroxyl group forms urethane bond once this
urethane bond is formed it is non toxic because
of that this polyurethanes are used in biomedical
implants. Also, fibers polyurethane fibers
those are used in biomedical field, so they
are used in catheters cardiac pumps sometimes
your oxygenator blood oxygenator membranes
silicones you know silicone is an inert material
silicone rubber that silicone is used for
making cosmetic surgery.
Say breast replacement, breast implant or
cosmetics other nose replacement nose surgery
or finger joint fingers artificial fingers
those are made from these silicones polyphenyl
alcohol and copolymers for making hydrogels
for drug delivery purposes and polyene isopropyle
acrylamide nipam polymer. In the last class
I told you that is used for making thermo
responsive controlled drug delivery devices
as well as for bio conjugates for separation.
And other things, these are various photographs
of composites made from carbon fiber and epoxy
carbon fiber polyether ethyl ether ketone
you see for joints bone plates made of composite
materials.
These are commercially available today these
composites high performance composites. So,
these are used in aerospace used in automobiles
as well as in structural items, here also
you see these are used in bone materials.
Screws you can have metal screws, now metal
screws are being replaced today by these composite
screws made from carbon fiber and peek poly
ethyl ether Ketone hip joint hip prosthesis
hip prosthesis. Again the same carbon fiber
peek injection molded composite are being
used today. So, it will take some minimum
time to explain these things. Next class I
I will see to cover these portions.
Thank you.
