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

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

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.

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

Monomers Used In The Synthesis Of

Synthetic Hydrogels:

Methods of

preparation of

HydrogelsCrosslinking

Isostatic Ultra High Pressure

Nucleophilic Substitution Reaction

Using Gelling Agents

Use Of Irradiation

Freeze Thawing

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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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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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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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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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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