Thermosensitive chitosan hydrogel for biomaterial applications

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Thermosensitive chitosan hydrogel for biomaterial
applications

• Rong Zeng
• Queen Mary, University of London
• Fudan University
• Supervisor Dr. Ray Smith
• Xin Chen

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Contents

• Background
• Chitosan
• Thermosensitive hydrogel
• Experiments Some results
• GP/chitosan
• thermosensitive chitosan hydrogel
• Future work

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Chitosan

• Structure

Biocompatibility Biodegradable Bioadhesive
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Chitosan Hydrogel
Temporary network Safe reversible Weak
mechanical properties
Permanent network Stable good mechanical
properties Toxic
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Thermosensitive hydrogel

• Temperature induced gelation
• Body temperature
• Injectable
• Topical drug delivery
• Tissue engineering

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GPchitosan

• Chenite et al.(2000) developed a novel approach
  to produce thermally sensitive neutral solutions
  based on chitosan /ß-glycerophosphate (GP)
  combinations.

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• Three types of interactions may be involved in
  the gelation process
• (1) electrostatic attraction between the ammonium
  groups of chitosan and the phosphate group of GP
• (2) hydrogen bonding between polymer chains as a
  consequence of reduced electrostatic repulsion
  after neutralization of the chitosan solution
  with GP
• (3) chitosanchitosan hydrophobic interactions.

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NMR test result

• 1H-NMR
• 13C-NMR
• 31P-NMR

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1H-NMR
3,4,6 5,6
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The line shifting is an indication of an exchange
process which is speed up by increasing the
temperature.
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T increase
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T increase
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13C-NMR
1,4,5,3,6,2
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31P-NMR
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Gp/cs
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Results

• 1H NMR data on GP/Chitosan mixture indicates that
  hydrogen bonds have been disrupted as a result of
  increasing temperature. If GP alone is heated,
  the observed shifts are much smaller.
• 13C NMR data was difficult to obtain for
  chitosan solutions, still trying to investigate
  the affect of temperature . But we expect no
  major shift.
• 31P data again indicate that in mixture of GP/
  Chitosan the hydrogen bonds have been disrupted.
  This is shown in a difference in shift value
  between GP and GP/Chitosan . We are closely
  examining the 31P-1H coupled data to verify this.

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Thermosensitive chitosan hydrogel

• PKa
• Method
• 1, alkaline chitosan solution
• 2, change the PH value of the solution by using
  different kind of acid solution

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alkaline chitosan solution (PH9.6)
pluronic solution (PH4.4)

• .

Mixed solution (PH7.0)
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T37-38?
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Future work
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• Thank you !

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