Technical
Extracel™ and Extracel™-HP Gelation Time Variation
For research use only
Hydrogel Description
The Extracel™ Hydrogel Kit is composed of Glycosil™ (CMHA-S, thiol-modified hyaluronic acid), Gelin-S™ (Gtn-DTPH, thiol-modified gelatin), Extralink™ (PEGDA, polyethylene glycol diacrylate), and degassed, deionized water (DG Water). The Extracel™-HP Hydrogel Kit has the same composition except that Glycosil is replaced with Heprasil™ (CMHA-S, thiol-modified hyaluronic acid with thiol-modified heparin). Solutions of Glycosil or Heprasil and Gelin-S form a transparent hydrogel when mixed with Extralink. The standard Extracel and Extracel-HP formulation assumes that Extralink will be added in a 1:4 volume ratio to an equal volume mixture of Glycosil/Heprasil + Gelin-S. The resulting gelation time will be ~20 minutes. The gelation time can be varied by changing the following parameters:
- pH of Glycosil + Gelin-S solution
- ratio of Glycosil to Gelin-S
- ratio of Extralink to Glycosil + Gelin-S
- amount of liquid used to resuspend Extralink (variation of Extralink concentration)
Below is data demonstrating how the gelation time varies with different conditions. All data is given for hydrogels made with Glycosil but applies equally to those made with Heprasil. If the gelation time is critical for your experiment, we recommend that a bench top gelation test be conducted prior to using the hydrogels for in vitro or in vivo experiments.
Glycosil + Gelin-S solution pH
The gelation time of the Extracel hydrogels is very pH sensitive – the higher the pH, the faster the gelation time. The data presented is for Glycosil only hydrogels. However, the same trend holds for Gelin-S containing hydrogels.
|
Glycosil, mL
|
Extralink, mL
|
pH
|
Gelation, min
|
|
0.5
|
0.125
|
6.76
|
0:50
|
|
0.5
|
0.125
|
7.07
|
0:32
|
|
0.5
|
0.125
|
7.28
|
0:23
|
|
0.5
|
0.125
|
7.60
|
0:12
|
|
0.5
|
0.125
|
8.59
|
0:02
|
Glycosil:Gelin-S
The gelation time of the Extracel hydrogels is slightly sensitive to the volume ratio of Glycosil to Gelin-S – the higher the Gelin-S amount, the slower the gelation time. Hydrogels made from 100% Gelin-S will not form hydrogels because they are too dilute.
|
Glycosil, mL
|
Gelin-S, mL
|
Extralink, mL
|
% Gelin-S
|
Gelation, min
|
|
0.500
|
0
|
0.125
|
0
|
0:10
|
|
0.375
|
0.125
|
0.125
|
25
|
0:11
|
|
0.250
|
0.250
|
0.125
|
50
|
0:15
|
|
0.125
|
0.375
|
0.125
|
75
|
0:20
|
Extralink:Glycosil + Gelin-S
The gelation time of the Extracel hydrogels is slightly sensitive to the volume ratio of Extralink to Glycosil + Gelin-S – the higher the Extralink amount, the faster the gelation time.
|
Glycosil, mL
|
Extralink, mL
|
Extralink volume ratio
|
Gelation, min
|
|
0.5
|
0.063
|
8
|
0:16
|
|
0.5
|
0.125
|
4
|
0:11
|
|
0.5
|
0.250
|
2
|
0:09
|
Extralink concentration
The gelation time of the Extracel hydrogels is sensitive to the concentration of Extralink used with Glycosil + Gelin-S – the higher the Extralink concentration, the faster the gelation time.
|
Glycosil, mL
|
Extralink, mL
|
Dissolved PEGDA volume, mL
|
Gelation, min
|
|
0.5
|
0.125
|
2.00
|
0:20
|
|
0.5
|
0.125
|
1.50
|
0:15
|
|
0.5
|
0.125
|
1.00
|
0:13
|
|
0.5
|
0.125
|
0.50
|
0:07
|
|
0.5
|
0.125
|
0.25
|
0:04
|
