Hydrogels for scientist as bsc _29758.pdf

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1. Hydrogels and their
applications
Presentation by Imed eddine Rouaiguia
(BMS -29758) for materials inspired by nature

2. Topics covered
○Definition of Hydrogels
○Types and classifications of hydrogels
○Characteristics and properties of hydrogels
○Application of hydrogels
○Summary

3. Definition
●3D network of hydrophilic polymer
●Absorb lots of fluids, insoluble in water
●Crosslinked polymers chains
●Gel form (dispersed phase: water, dispersion
medium: polymer)
●Exhibit a wide range of material characteristics
Figure 1: smart hydrogels.

4. Classification of Hydrogels
Figure 2: Classification of hydrogels.

5. Classification based on cross-linking
1.Physically cross-linked hydrogels:
○Non-covalent interactions (H-bonding or van der Waals forces,
chain Entanglements: ..)
○Formed by physical processes (e.g., heating ,cooling)
○Offer high swelling capacity
2.Chemically cross-linked hydrogels
○Covalent bond
○Permanent and stable networks formed

6. Classification based on polymeric composition
●Homopolymeric hydrogels:
○Composed of one monomer
●Copolymeric hydrogels:
○Two or more different monomeric species
○Having at least one hydrophilic constituent

7. Classification based on cross-linking
3. Multipolymer interpenetrating polymeric hydrogels
○Full-IPNs: Multiple independent, interpenetrating cross-linked networks.
○Semi-IPNs: One cross-linked network with non-cross-linked polymers
entangled within.
Figure 3: Schematic representation of crosslinked networks.

8. Classification based on source
●Natural hydrogels:
○Common ones are Gelatin and collagen.
○Properties include large absorption rate, biodegradability
and biocompatibility.
●Synthetic hydrogels:
○Synthesis using polyacrylamide (PA) and polyethylene
glycol (PEG), etc.
○Excellent mechanical properties, can cause cytotoxicity

9. Properties of Hydrogels

10. Swelling behavior of hydrogels
●The absorption and retention of water in the polymeric
network
●Key factors are molecular weight and cross-linking
●Equilibrium swelling can be calculated with:

11. Swelling behavior of hydrogels
●Figure 4a shows a lyophilized hydrogel in its initial state
●Equilibrium swelling state after immersing it in PBS is shown
in figure 4b
●Higher crosslinking degree have lower swelling ability
●Result in a lower elasticity and mobility of the polymeric
chains. Thus, low capacity to absorb PBS.
Figure 4: a) Swelling of hydrogels from lyophilized
state b) equilibrium swelling ratio

12. Further properties of Hydrogels
●Biocompatibility:
○Non-toxic and non-immunogenic materials
○Controlled adhesion properties
○Resemblance to the ECM of soft tissues
○Porous structure through crosslinking
●Biodegradability
○Controlled breakdown in tissue, promote cell secretions
and drug release
○Break down after new tissue is merged
Figure 5: Properties of hydrogels

13. Further properties of Hydrogels
●Mechanical properties:
○Higher swelling decreases the mechanical properties
○Nanocomposites hydrogels
○Improve mechanical durability
○Mechanical resilience is indispensable in the field of
medicine
Figure 5: Properties of hydrogels

14. Application of Hydrogels
In bone tissue engineering

15. Hydrogels in bone tissue engineering
●Hydrogels can be used in bone regeneration
●Osteoclast tissue cells are responsible for bone
resorption and osteoblast for bone formation
●Remodeling of autografts arises from natural
processes
●Allograft bones are unviable tissues
Figure 6 : Hydrogel-assisted bone regeneration

16. Hydrogels in bone tissue engineering
●These issues are solved by tissue engineering
●Delivery of cells and growth factors promote
regeneration and healing
Figure 7 : Hydrogel-assisted bone regeneration

17. Summary
●Hydrogels are 3D network of hydrophilic crosslinked polymers
●Hydrogels have multiple classifications, have unique characteristics
●In medicine, they serve as a structural carrier for the damaged area
●Enable internal healing processes to rebuild the lost bone mass

18. Reference
[1] Fink, Johannes Karl, and Russell Richardson. The Chemistry of Bio-Based Polymers, John Wiley & Sons, 2014, chapter 2.
[2] Yang, Guang et al. Bioinspired Materials Science and Engineering. First edition. Hoboken, NJ: Wiley, 2018. Print. 22-1
[3] Singh, Ravindra Pratap, and Kshitij Rb Singh. Bionanomaterials for Environmental and Agricultural Applications, 2022, chapter 1.
[4] Shirin Ghaderi, UCL Center for Nanotechnology and Regenerative Medicine, chapter 2
[5] Chu, Liang-Yin et al. Smart Hydrogel Functional Materials. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013, chapter 3
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19. Reference (Pictures)
[1] Picture 1, https://www.scapahealthcare.com/images/default-source/healthcare/blog-posts/hydrogel-blog-2_image.jpg?sfvrsn=a4b27fd7_0
[2] Picture 2, Shahid Ali Khan. Antimicrobial Characteristics, Tissue Engineering, Drug Delivery Vehicle, 2024, chapter 7, p108
[3] Picture 3 Veena Koul, Handbook of polymers for pharmaceutical technologies, chapter 05, p125
[4] Picture 4, https://www.mdpi.com/2073-4360/13/4/650
[5] Picture 5, Shahid Ali Khan. Antimicrobial Characteristics, Tissue Engineering, Drug Delivery Vehicle, 2024, chapter 3, p39
[6] Picture 6, https://www.cancer.gov/publications/dictionaries/cancer-terms/def/bone-tissue
[7] Picture 7, https://doi.org/10.1515/9783111334080-001
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