Affinity Grid Coatings for Stable Cryo-EM Protein Capture

The patent uses composite materials by combining graphene oxide with NTA (nitrilotriacetic acid) to create a stable affinity coating. The graphene oxide provides structural stability and mechanical support, while NTA provides the affinity capture capability for histidine-tagged proteins. This composite approach resolves the contradiction by integrating the stabilizing function of graphene oxide with the selective capture function of NTA, achieving both film stability and selective capture capability simultaneously.

The patent applies local quality by functionalizing specific regions of the graphene oxide surface with NTA groups. The graphene oxide provides a stable base structure, while the NTA-functionalized regions provide selective affinity capture. This localized functional approach allows the grid to maintain stability across the entire surface while providing selective capture only at the functionalized sites, reducing non-specific binding compared to uniform affinity coatings.

The patent merges the purification function with the grid coating itself. Instead of using separate purification steps before grid preparation, the affinity-functionalized graphene oxide coating performs on-grid purification during sample application. This integration of purification and grid preparation functions reduces the number of separate steps, decreasing overall preparation time while maintaining protein purity through selective affinity capture.