Loading characteristics and chemical stability of headgroup‐functionalized poly(ethylene glycol)‐lipid ligand tethers on polypropylene capillary‐channeled polymer fibers

Polypropylene capillary‐channeled polymer fibers have been modified by adsorption of headgroup‐functionalized poly(ethylene glycol)‐lipids to generate a species‐specific stationary phase. In order to study ligand binding characteristics, a fluorescein‐labeled poly(ethylene glycol)‐lipid was used as a model system. Breakthrough curves and frontal analysis were employed to characterize the surface loading characteristics across a range of lipid concentrations and mobile phase flow rates. Efficient mass transfer and fluid transport yield a linear adsorption isotherm up to the maximum loading concentration of 3 mg/mL, at a linear velocity of 57.1 mm/s. Under these conditions, the dynamic binding capacity was found to be 1.52 mg/g of fiber support. Variation of the linear velocity from 8.6 to 57.1 mm/s showed only small changes in breakthrough volume. The maximum capacity of 1.8 mg/g is found under conditions of a load velocity of 34.2 mm/s and a concentration of 3 mg/mL lipid. Exposure of the lipid modified fibers to several challenge solvents reveals a chemically robust system, with only 50% acetonitrile and hexanes able to disrupt the lipid adsorption. The straightforward capillary‐channeled polymer fiber surface modification with headgroup‐functionalized lipids provides both a diverse yet practically robust ligand tethering system.