Hello everyone,
I wanted to form a solution of a mixture of rat tail collagen type I and 600 Da PEGDA. I kept everything on ice except the PEGDA, and added a little bit of phenol red into the mixture to visualize the pH. I couldn't keep the PEGDA chilled because at colder temperature it is a waxy solid. I also used a pH meter/temperature probe to continuously monitor the solution. I noticed that as soon as I added the PEGDA into the collagen/phenol red, the PEGDA came out of my pipet tip like sludge as soon as it hit the collagen solution. The solution did not change from its yellow color and and only went up to about a pH of 5. I stirred the PEGDA into the collagen until it appeared well-mixed. I then added the photoinitiator, and base to raise the pH so that it would gel. It did turn pinkish-red. I put it in the incubator at 37 degrees Celsius because I know at 37 it gels very quickly.
I checked it at several time points, but even after two hours, the solution was still liquid. I centrifuged it at about 3000 RPMs and I noticed something aggregate at the bottom. I mixed it back up to see if it could still crosslink via UV, and indeed it could.
Has this happened to anyone else before?
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