I'm currently working with a hydrogel - Stearate Modified Methylcellulose Acrylate (SMMA), which is a photo-crosslinked gel. The photoinitiators i'm using are Eosin Y, Triethanolamine, and 1-vinyl-2-pyrrolidinone, which sets the gel upon exposure to green light.
I am currently using a 2% gel, which I've dissolved in 10x PBS and the photoinitiators (1mM, 125mM, and 20mM respectively), and setting the gel with a 510nm Green LED array. I'm using 10x PBS because it's the only way to get the gel to crosslink in a reasonable amount of time (10-20 minutes, compared to +2 hours with 1x).
The issue that I'm having is that when I add media (1x DMEM), or any other kind of solution to the crosslinked gel, or add the set gel to a solution, within 5-10 minutes, it's completely dissolved. As I'm trying to use this gel for 3D cell culture, having it dissolve is a bit of a problem...
Does anyone out there know how to solve this issue, or have any suggestions?
Dear lachlan,
The responsible reason for dissolving the hydrogel is incomplete formation of 3D polymeric structure and other one is poor grafting yield. Firstly, optimized the parameters, such as, gel concentration, photoinitiator by varying the concentration.
Hi there,
in second instamnce you coud try to change photoinitiator trying Irgacure.
Good luck
Cesare Gargioli Thanks for your response. I would rather avoid using Irgacure, as it requires UV light to crosslink (at least as far as I understand it), and I'd prefer to minimize any exposure to potentially damaging elements.
Jagdeep Singh and Md. Abdur Rahman
I am going to toy around a bit with my concentrations. Thank you for your advice.
Perhaps you could do a calculation to estimate the concentration of the reactive groups you want to participate in the crosslinking. Work that I did a number of years ago suggested C=C concentrations of ~3mmol/g (dry basis) were needed to provide tight crosslinking (surface coatings). That might be too high for your objectives but would give you an upper limit to approach. You may find it advantageous to include (water soluble) polyethylene glycol diacrylates as auxiliary crosslinkers; PEG600DA would be a good place to start.
Sometimes the photocrosslinking occurs only in the surface.
I think it is not bulk crosslinking.
Dear Beckingham,
As per my opinion, the hydrogel may suffer from poor crosslinking. You may increase the dose of crosslinker. Also, grafting may be poor. Additionally, the hydrophobic backbone may dissolve completely in organic solvents.
I use UV at low penetrance for polymerization routinely also with human primary cells , without any damage.
Good luck
Hi Cesare Gargioli
I'm going to give the Irgacure UV crosslinking a try. Is there a specific one that you use, and is there a required light intensity that I need to initiate the crosslinking? For instance, could I use the UV light that we use to sterilize our culture hoods?
Hi,
we normaly use CIBA Irgacure, but I do not think is a problem from other source.
Regarding UV, hood UV I think are too strong, we use 365 nm, 1.3 mW/cm2, low penetrance UV.
Good luck
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