Hi,

I am working on a hydrogel consisting of PEG-maleimide (PEG-mal, 4-armed) and Gelatin-Furan (Gel-fur) via a Diels-Alder crosslinking mechanism. I synthesized Gel-fur by combining Gelatin and furfuryl amine and proved the conjugation by using 1H-NMR. The results were good (peaks were identified) and I am not worried about Gel-fur.

However, PEG-mal was so unpredicted and hard to handle (FYI, I purchased 4-armed-PEG-mal).

First, I initially fabricated firm hydrogels for initial gelation optimization, but it starts to behave in an unrepeatable manner after a while. In other words, the first set of hydrogels was optimized according to PEG:Gel ratio and different gelation times obtained. However, the next set of hydrogels (with the SAME ratio) showed different strengths and gelation times (this unrepeatability is the main problem). Interestingly, the concentration of crosslinker (PEG-mal) with which hydrogels were fabricated was so higher than the one in my "reference" research article. For example, I optimized PEG:Gel ratio of 0.8:1 and the gelation time of 10 hours (1st gelation set), while the authors of my reference research had optimized the ratio of 0.4:1 and the gelation time of 2 hours, even with 2-armed PEG-mal.

I guess there is something wrong or missing with the gelation procedure, such as the stability of PEG-mal in PBS solution.

I hope someone can help me.

Thanks

Amirreza