Using 20KDa PEG DA crosslinked with 2000Da PEG Dithol formed via Michael type addition reaction.
This is the method I have use for other types of hydrogels:
1) Prepare your hydrogel samples into regular shapes using a mold of some sort and with a mass of ~1-10 g.
2) Weigh them on a set of scales to get the initial wet weight (Wi)
3) Immerse the hydrogels in a small container of water (or buffer of your choice), and place in a controlled temperature environment.
4) Wait for certain amount of time. This depends on the time intervals you choose. I would recommend expanding time intervals on the first day like 1 h, 2 h, 4 h, 8 h, 12 h, 24 h. And then every day after that. If your hydrogel is very slow to swell you might even go to weekly measurements or twice a week measurements.
5) When you go to re-weight the hydrogel samples, take them out of the solution, blot them dry (just the loose surface water) and place them on the scales to get the weight at a specific time (Wt).
You can then plot change in mass over time (assuming the only mass change is from migration of water into/out of the hydrogel. Mass change = Wt / Wi x 100%
You can also plot swelling ratio over time if you can work out how much dry materials were used in the initial sample. Swelling ratio (SW) = swollen mass / dry mass.
You might want to check to see if some of your uncross-linked polymer has leeched out by lyophilising your final sample and weighing it to compare to the original dry mass of materials.
Check out my publication where I have reported all of this for cross-linked gelatin hydrogels if you like .
Article Gelapin, a degradable genipin cross-linked gelatin hydrogel
Dear Karthik, you will need one of the macromonomers to have a higher functionality than 2 to get a crosslinked gel; PEG-DA + PEG-2SH will form a linear soluble polymer. Then follow Damians advice, but you may also want to do use a densitometric balance to calculate volumetric degree of swelling and swelling ratios that you need for calculating Mc and mesh size etc using Flory et al equation etc. See Biomaterials 19 (1998) 1343—1352. Best regards. Deon
- Badges
- Science topic
- Similar topics
- Gels