biomaterials ppt

Thermosensitive chitosan hydrogel for biomaterial applications : 

Thermosensitive chitosan hydrogel for biomaterial applications Rong Zeng Queen Mary, University of London Fudan University Supervisor : Dr. Ray Smith Xin Chen

Contents : 

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

Chitosan : 

Chitosan Structure Biocompatibility Biodegradable Bioadhesive

Chitosan Hydrogel : 

Chitosan Hydrogel Permanent network Stable &good mechanical properties Toxic Temporary network Safe & reversible Weak mechanical properties

Slide 5: 

Temperature induced gelation Body temperature Injectable Topical drug delivery Tissue engineering Thermosensitive hydrogel

GP&chitosan : 

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

Slide 7: 

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) chitosan–chitosan hydrophobic interactions.

NMR test result : 

NMR test result 1H-NMR 13C-NMR 31P-NMR

1H-NMR : 

1H-NMR 3,4,6 5,6

Slide 10: 

The line shifting is an indication of an exchange process which is speed up by increasing the temperature.

Slide 11: 

T increase

Slide 13: 

T increase

13C-NMR : 

13C-NMR 1,4,5,3,6,2

31P-NMR : 

31P-NMR

Slide 18: 

Gp/cs

Results : 

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.

Thermosensitive chitosan hydrogel : 

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

: 

Slide 22: 

. alkaline chitosan solution (PH=9.6) pluronic solution (PH=4.4) Mixed solution (PH=7.0)

Slide 23: 

T=37-38℃

Future work : 

Future work

Slide 25: 

Thank you !