For anion exchange you need to have the protein at a pH at least above 1 unit from the pI. If the protein is happy with this, then go ahead and buy the micro-spin column. I would rather have the protein positively charged and use a cation exchange spin column. Irrespective of this, you cannot expect to completely purify a protein using a single chromatographic technique.

You may use gravity flow or a spin column format filled with any polymeric backbone SCX resin. Since the pI is very high, you should try to purify POI by performing salt gradient elution. pH gradient would not be preferable in this case due to the need for aggressive alkaline conditions for successful elution.

I would try isoelectric precipitation first...Most of the proteins will be soluble in alkaline conditions but at 11.5 assuming your target will be pelleted...Ion exchange resolution would be better for critical pairs and for proteins bearing close pI. For 11.5 you may not need a high resolution....

You could use a cation exchange resin. You can find some examples here:

https://www.cytivalifesciences.com/en/us/shop/chromatography/resins/ion-exchange?sort=NameAsc&chunk=1

https://www.thermofisher.com/us/en/home/life-science/bioproduction/poros-chromatography-resin/bioprocess-resins/ion-exchange-resins/cation-exchange-resins.html

Hello Jose, mi jefe. Hope that you are doing well. Here is an example purification of a cationic protein with a pI 11.35. Hope it is useful. Best regards.

Thanks a lot for your help and valuable advice.

Best regards,

Jose