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Introduction  to Hydrogels :

The research on hydrogels is more than four decades old but there has been a tremendous growth in the recent past because of their unique bulk and surface properties. They form the basis of many novel drug delivery systems.Hydrogels can be made to respond to the environment and the extent of the response can be controlled.The environmental conditions to which a hydrogel can be made responsive pH,temperature,electric field,ionic strength,salt type,solvent,external stress,light or a combination of these.

It is because of these unique properties that these classes of polymer based systems embrace numerous pharmaceutical and bio medical applications. Hydrogels are water swollen three dimensional structures composed of primarily hydrophilic polymers. These are cross linked macro molecular networks that are insoluble but are able to swell rapidly in water or biological fluids.

 polymer hydrogel picture

Classification of hydrogels:

Based on the method of preparation, hydrogels are classified into:

A) Homopolymer hydrogels

B) Co-polymer hydrogels

C) Multi polymer hydrogels

Based on the ionic charges hydrogels can be classified into :

A) Neutral hydrogels

B) Anionic hydrogels

C) Cationic hydrogels

D) Ampholytic hydrogels

Based on the structure hydrogels can be classified into :

A) Amorphous hydrogels

B) Semi-crystalline hydrogels

C) Hydrogen bonded hydrogels

Based on the mechanism controlling the drug release they are classified into:

A) Diffusion controlled release systems

B) Swelling controlled release systems

C) Chemically controlled release systems

D) Environment responsive systems

Structure  of hydrogel : The structure of an ideal network of tetra functional covalent cross links.

Materials used in the preparation of hydrogels :

Different polymers can be used for the development of hydrogel systems including cellulose derivatives, natural gums, polycrylates and gelatin.

Preparation : Hydrogels can be prepared by swelling cross linked structures in water or in biological fluids containing water.Commonly hydrogels are prepared by free radical polymerization of hydrophilic vinyl polymers.Cross links can be induced by radiation. Radiation reactions include electron beams, gamma rays, x rays or U.V. light.

Applications :

Effect of hydrogels water content on chondrocyte signalling.

Opthalmic use : The artificial cornea is made of a dual network hydrogel with a clear center and peripheral pores. Cells infilterate the pores and secrete collagen, which integrates artificial cornea into the surrounding natural tissue.


About the Author

Devisarvani's picture
Author: Devisarvani


Bobby's picture

Nice collection sarvani,
can u plz tell me where these hydrogels can be applied other than opthalmic use..


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Raghavendhra naveen Chennoju's picture

Dear sarvani,
Nice presentation, but I have some doubts and clarifications regarding your topic which I have discussed below, Can you pls clarify them:
-You said that some types of hydrogels are used in the manufacture of artificial corneas, what is the polymer used in this manufacture and under which classification of hydrogels it is placed?

-As you given in the classification, the forth classification is based on mechanism controlling the drug release .Can you give me some more information regarding these mechanisms i.e. Diffusion, Swelling, Chemically controlled release systems and their major applications in drug delivery system.

-Can you give me some names of commercially available hydrogels with brand names?

Ragha Naveen

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Zarrin Faria's picture

Dear .....
Hydrogels are great innovations in the field of novel drug delivery system....as you have mentioned that the technology started about 40 years ago...but still till now not many drugs are available using this technology ...why is it so???
Kindly reply...
Faria Zarrin
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kranthi kumar's picture

HI sarvani,
Good presentation, You have mentioned the advantages in the starting, is it applicable only in the above two areas??
Is this used for controlled drug release?? if so where is it implimented ??

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Navin_pharmacist's picture

Hi Sarvani

u have choosen nice topic which is recently came in limelight.

can u give the detail preparation procedures and any applications in oral delivery ?

Naveen Chella

Naveen Chella
SAGAR's picture

u have presented a good topic but short synopsis

Shiv Majumdar's picture

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Dear sarvani,

Very good pictorial representation. Keep it up.