Searching for super protein-resistant synthetic membrane surfaces using high throughput: Solvent effects

With seven monomers (four polyethylene glycol (PEG) and three amine monomers) chosen as “winners” from a previous high throughput study, we have refined and improved their grafting, filtration and anti-fouling characteristics. To do this, we varied the composition of a series of alcohol/water mixtures that was characterized by their solubility parameters (δT), for monomer solvents during grafting. A novel high throughput (HT) approach allowed us to select conditions with high statistical confidence for photo-graft polymerization (PGP) (i.e., best solvent and monomer) that produced the highest degree of grafting, intermediate permeation flux and sieving values, and the lowest fouling index values. These super protein-resistant graft modified synthetic membrane surfaces are synthesized from polyethylene glycol (PEG-300) in water (δT = 47.8 MPa1/2) and N-isopropylacrylamide (NIPA) grafted in ethanol/water (50 wt%/50 wt%) mixture (δT = 35.9 MPa1/2), respectively. They exhibited very low protein fouling (ℜ = 0.31 ± 0.06 and 0.28 ± 0.16), very good relative flux values (or normalized resistances, Rw,mod/Rinitial = 1.06 ± 0.08 and 1.89 ± 0.31) and increased bovine serum albumin (BSA) sieving, respectively.