It's definitely a teachable moment. When using dialysis bag clips, I always wrap a rubber band tightly around the clip to keep it from popping open.

If the protein is valuable enough to spend the effort to recover it, you could mix some ion exchange resin, such as Q-Sepharose into the dialysis bath, stir it for a while (but not so hard that the beads get crushed), then collect the beads in a column. Then elute the protein with a high-salt buffer in a small volume and dialyze it again.

I concur with Adam' answer and I share your disappointment, having myself lost several preps due to leakage of dialysis bags (I was purifying cellulases). Since you seem to work with a protein originally carrying a His tag, starting over with a new prep will most likely involve less cost, time and hassle than trying to recover it from 2 L of dialysis buffer.

Dear Michele

For the future, i suggest to you to evaluate the desalting approach as alternative to dialysis to perform buffer exchange, it is faster and risks of sample lost are very low.

if you are interested you can see the following video avaialble on my blof, ProteoCool about it

https://www.blogger.com/video.g?token=AD6v5dzeX21U_Er6jBChQIhE5zWtQhNjRjNXRPR7qk7KfWWSQxhf8PbUn4R6KLL0pn_7tU92M0-B3kEUHO9IkTpelmdO79QR53uSg29ZFV3j5D-siHAamTu1y2wOEQ8S4As_wpxzLvA

https://www.blogger.com/video.g?token=AD6v5dwNlVHz3BclDT9RLY-6KbEEqkS3RnRdHn4BqTsZW4j_prf3KZwHDMTzRYT-B9Yifvmde7RdExL5AArLFtg1Q13fu4-83o3M8bCka1jJ5PfWFK8B53BOpx6YrzvLr2qDiPgT15c

For the current sample. It depends from the properties of the protein (eg isoelectric point, MW) and matherial that you have available immediatelly in your lab.

- Ionic exchange, as suggested from Adam could be a solution if your current buffer as the right PH and do not contain ions that may not alllow to the protein to bind to the coloumn.

- Protein concentration with amicom or TFF cassette could be one other option, expecially if your protein has high MW and you can use high cut off membranes.

- Precipitation with ammoniun sulfate could be one other way, but , you need a lot of ammonium sultate and it depends it the precipitation in some way destablize your protein. (Generally i do not like this steps)

of course those step need matherials and are time consuming so you need to evaluate if is faster and cheaper restart your preparation from the beginning of nor.

ps: when you are doing dialisys perform a double clousure (2 clamps or 1 clamps and 1 knot and do not fill completelly the bag but leave some empty space, because some times the volume can increase and bag open or broke)

good luck

Manuele