polymer hydrogel

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



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.



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



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.



Classification of hydro gels :

Gum Pectin Starch



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 =



Applications of hydro gel in medical science :

1. Lubricants :-

Hydrogel coating have been applied to catheters to protect

urethra & form a hydrophilic lubricious surface.



2. Contact lens :-

Original material for hydrogel contact lens- poly(2-hydroxy ethyl

methacrylate)or poly (HEMA)



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.



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



4. As drug delivery system : Pluronic-PAA ,known as

smart hydrogel show unique characteristic of thermo

reversible gelation.

Network structure of Pluronic-PAA



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.



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



5. For tissue engineering :



The development of effectivecartilage regeneration system

depends on-

Hyrogels promote cell growth &integrates with the surroundingtissue, so it is convientlyinjectable.



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.



Thank You

polymer hydrogel

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