This document discusses hydrogels, which are cross-linked polymer networks that can absorb large amounts of water. It classifies hydrogels based on their structure, charge, and mechanism of drug release. It also outlines common monomers used to synthesize hydrogels and various preparation methods like crosslinking. The document notes advantages like biocompatibility and ability to inject hydrogels, as well as disadvantages such as low mechanical strength. It concludes that hydrogels can be used for targeted drug delivery, as biosensors, and in wound healing and tissue regeneration due to their responsiveness to stimuli.

1. Hydrogels
-Biomaterial
Sciences
Under the guidance of:
Dr. Monalisa Mukherjee
By:
Sukriti Singh
BTBM/13/242
A0523113081
Sem 3, Sec D
AIB, Amity University, Noida

2. CONTENTS:
• Introduction
• Classification of Hydrogels
• Advantages of Hydrogels
• Disadvantages of Hydrogels
• Types of Hydrogels
• Monomers Used In The Synthesis of Synthetic Hydrogels
• Method of Preparation of Hydrogels
• Common Uses For Hydrogels
• Summary and conclusions
• References

3. Introduction
Hydrogel is a network of polymer chains that are hydrophilic, water insoluble,
sometimes found as a colloidal gel in which water is the dispersion medium.
 Hydrogels are highly absorbent natural or synthetic polymers.
Hydrogels are cross-linked polymer networks that absorb substantial amounts of
aqueous solutions.
 Hydrogels can contain over 99.9% water.
 Hydrogels are three-dimensional, hydrophilic, polymeric networks capable of
imbibing large amounts of water or biological fluids.
The networks are composed of homopolymers or copolymers, and are insoluble
due to the presence of chemical crosslinks (tie-points, junctions), or physical
crosslinks, such as entanglements or crystallites.
The high water content of the materials contributes to their biocompatibility.
These crosslinks provide the network structure and physical integrity.
These hydrogels exhibit a thermodynamic compatibility with water which allows
them to swell in aqueous media.

4. Classification of Hydrogels
STRUCTURE
• Amorphous Hydrogels
• Semi-crystalline Hydrogels
• Hydrogen Bonded Hydrogels
CHARGE
• Neutral Hydrogels
• Anionic Hydrogels
• Cationic Hydrogels
• Ampholytic Hydrogels
MECHANISM
OF DRUG
RELEASE
• Diffusion Controlled Release Systems
• Swelling Controlled Release Systems
• Chemically Controlled Release Systems
• Environment Responsive Systems
METHOD OF
PREPARATION
• Homopolymer Hydrogels
• Co-polymer Hydrogels
• Multi Polymer Hydrogels

5. Monomers Used In The Synthesis Of
Synthetic Hydrogels:

7. Methods of
preparation of
Hydrogels Crosslinking
Isostatic Ultra High Pressure
Nucleophilic Substitution Reaction
Using Gelling Agents
Use Of Irradiation
Freeze Thawing

8. Advantage
of
Hydrogels:
Hydrogels possess a degree of flexibility very similar
to natural tissue, due to their significant water content.
 Entrapment of microbial cells within Hydrogel
beads has the advantage of low toxicity.
 Environmentally sensitive Hydrogels have the
ability to sense changes of pH, temperature, or the
concentration of metabolite and release their load as
result of such a change.
Timed release of growth factors and other nutrients
to ensure proper tissue growth.
 Hydrogels have good transport properties.
 Hydrogels are Biocompatible.
 Hydrogels can be injected.
 Hydrogels are easy to modify.
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9. Disadvantages
of Hydrogels:
Hydrogels are expensive.
 Hydrogels causes sensation felt by movement of the
maggots.
 Hydrogels causes thrombosis at Anastomosis sites.
 The surgical risk associated with the device
implantation and retrieval.
 Hydrogels are non-adherent; they may need to be
secured by a secondary dressing.
Hydrogels used as contact lenses causes lens
deposition, hypoxia, dehydration and red eye reactions.
 Hydrogels have low mechanical strength.
 Difficulty in handling.
 Difficulty in loading.
 Difficulty in Sterilization.
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10. Common Uses
For Hydrogels:
MISCELLANEOUS
• Used as Medical electrodes in ECG.
• Used as Breast implants.
BIOTECHNOLOGY
• Used as Biosensors that are responsive to
specific molecules, such as glucose or
antigens.
SANITARY
PURPOSE
• Used in disposable diapers where they
absorb urine, or in sanitary napkins.
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11. Summary &
Conclusion:
Recent developments in the field of polymer science and technology
has led to the development of various stimuli sensitive hydrogels like
pH, temperature sensitive, which are used for the targeted delivery of
proteins to colon, and chemotherapeutic agents to tumors.
Some environmental variables, such as low pH and elevated
temperatures, are found in the body.
 For this reason, either pH-sensitive and/or temperature sensitive
hydrogels can be used for site-specific controlled drug delivery.
Hydrogels that are responsive to specific molecules, such as glucose or
antigens, can be used as biosensors as well as drug delivery systems.
 The hydrogels may be suitable as a wound substitutes and can be used
in wound healing.
New synthetic methods have been used to prepare homo- and co-
polymeric hydrogels for a side range of drugs, peptides, and protein
delivery applications.
 Hydrogels are also used in regenerating human tissue cells.
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12. References:
1.Remington: The Science and Practice of Pharmacy. Published
by Lippincott Williams & Wilkins, 2005.Twenty-First
Editions. P.NO. 294,756,867,868.
2. Handbook of Pharmaceutical Excipients, A. Wade and P.J.
Weller ed., The Pharmaceutical Press, London, 1994, pp.
229–232.
3. British Pharmacopoeia 2002, the Stationary Office, London,
2002, p. 2092–2094.
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