Rehydratable gel for rapid loading of nanoliter solution and its application in protein crystallization

Abstract

In the work presented, rehydratable polyacrylamide gel is introduced as a medium to uptake and store nanoliter protein solutions in microwells for multiplex bioanalysis. The polyacrylamide gel, produced and stored in the microwells, shrank by 97% upon dehydration and could be reversibly rehydrated to 95% of the initial volume by absorbing aqueous solution. We employed the rehydratable gel to load aqueous solutions of different proteins with molecular weights in the range of 14.7–250 kDa. The protein loading occurred simultaneously with the gel rehydration and reached saturated state in 5 min. The relative protein concentrations in the gel ranged from 92% to 53%, depending on the molecular weight of the proteins. Particularly, the rehydratable gel had a much higher protein loading efficiency than the fresh gel. We applied the protein-carrying gel to the crystallization of four model proteins in the microwells and produced diffraction-quality protein crystals. The rehydratable gel is simple to fabricate, efficient to load with protein, and has good capacity for storing the protein solutions in microwells with minimal dilution effects on the protein solution. The rehydratable gel incorporated microwell chip should be useful in multiplex analysis that requires small sample consumption and high throughput.