Nonfouling NTA-PEG-Based TEM Grid Coatings for Selective Capture of Histidine-Tagged Protein Targets from Cell Lysates

We report the preparation and performance of TEM grids bearing stabilized nonfouling lipid monolayer coatings. These films contain NTA capture ligands of controllable areal density at the distal end of a flexible poly(ethylene glycol) 2000 (PEG2000) spacer to avoid preferred orientation of surface-bound histidine-tagged (His-tag) protein targets. Langmuir–Schaefer deposition at 30 mN/m of mixed monolayers containing two novel synthetic lipids—1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[(5-amido-1-carboxypentyl)iminodiacetic acid]polyethylene glycolamide 2000) (NTA-PEG2000-DSPE) and 1,2-(tricosa-10′,12′-diynoyl)-sn-glycero-3-phosphoethanolamine-N-(methoxypolyethylene glycolamide 350) (mPEG350-DTPE)—in 1:99 and 5:95 molar ratios prior to treatment with a 5 min, 254 nm light exposure was used for grid fabrication. These conditions were designed to limit nonspecific protein adsorption onto the stabilized lipid coating by favoring the formation of a mPEG350 brush layer below a flexible, mushroom conform...