polymer hydrogel
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8/7/2019 Polymer hydrogel
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POLYMER HYDROGEL: A new era
in Medical Science
Seminar by: Saurabh BagalDept of Polymer Science & Technology
University of Calcutta92,A.P.C. Road,Kolkata-700009
8/7/2019 Polymer hydrogel
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What is Hydrogel? Three dimensional network of
hydrophilic polymers held together by covalent bondsor hydrogen or ionic bonds.
� Polymers which form hydrogels are- sodium
poyacrylate, poly(vinyl alcohol) etc.
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Polymer chains usually exist in the shape of randomly
coiled molecules.
Negative charges repel each other &polymer chain tend to uncoil.
Water molecules are attracted to (-)vecharge by hydrogen bonding
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Selection of monomer for formation of hydrogel :
� The monomer should be acidic or anionic, basic or cationic &
neutral.
Neutral monomer contains-
i> Hydrophilic part- contributes to swelling.
ii> Hydrophobic part- improves mechanical strength.
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Classification of hydro gels :
Gum Pectin Starch
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Properties of hydro gel :
Water content & swelling
ratio : Permeability :
�
Permeability of targetmolecules is of utmost
importance.
For instance, oxygen
permeation for contact
lens, releasing drugs &proteins for drug delivery
system
Water Content =
Wt. of the water X 100
Wt. of the water + Wt. of dry gel
Wt. of the swollen gel
Wt. of the dry gelSwelling Ratio =
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Applications of hydro gel in medical science :
1. Lubricants :-
Hydrogel coating have been applied to catheters to protect
urethra & form a hydrophilic lubricious surface.
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2. Contact lens :-
Original material for hydrogel contact lens- poly(2-hydroxy ethyl
methacrylate)or poly (HEMA)
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Contact lenses are mainly of two types :
Low water content
� Advantages : i) Greater
tensile strength.
ii) Less breakage & longerlife span.
Disadvantages : i) Greater
tendency to cause edema
ii) Tendency to cause
vascularisation.
High water content
� Advantages : i) Better
comfort.
ii) Faster adaptation &longer wearing time.
Disadvantages : i) Shorter
life span & greater fragility.
ii) More deposits,
especially white spots.
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3. F r ressi g :
� Hy r gel p ssesses allthe characteristics f rs ccessf l c veri g
material.
� Vari s hy r gel
c mp sites pr tect
agai st i fecti
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4. As drug delivery system : Pluronic-PAA ,known as
smart hydrogel show unique characteristic of thermo
reversible gelation.
Network structure of Pluronic-PAA
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At body temp Pluronic-PAA forms hydrogel,so drug
molecule can pass through the hyrogel network at a
steady rate. It is also bio-adhesive, so it can be used todeliver drug to a specific target site.
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Hydrogels are used as
endoscopic injection of bulkyagents for treatment of stressurinary incontinence
An injectable chitosan-based
hydrogel is used to form insituan implant for orthopedicapplications
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5. For tissue engineering :
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The development of effectivecartilage regeneration system
depends on-
Hyrogels promote cell growth &integrates with the surroundingtissue, so it is convientlyinjectable.
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Conclusion
� Hydrogel can also acts as immobilized bio-
catalyst, immunoisolative barrier or
biomimetic actuators.
So hydrogel is marching towards a special
position in modern medical science.
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