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

Abstract

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.

Evaluation of synthesized lipid tethered ligands for surface functionalization of polypropylene capillary-channeled polymer fiber stationary phases

“…38 Following fiber functionalization with the commercial and synthesized FITC-LTLs at the same molar concentration (4.4 μM), the PP C-CP SPE tips were washed with approximately 600 tip (bed) volumes (i.e., 3 mL) of either PBS buffer or 0.1% Tween-20 solution, and then fluorescently imaged to assess the overall retention of the FITC-labeled ligands (Fig. exposure to common mobile phase and column regeneration media.…”

“…37 The adsorption is driven by the strong hydrophobic interaction between the lipid tail of LTLs ( Fig. 38,39 The poly(ethylene glycol) (PEG) chain in the LTL is a spacer that extends the functional ligand from the hydrophobic PP surface to the hydrophilic mobile phase. The strength of this coupling, and indeed evidence for the intercalation of the lipid chain into hydrophobic polymer matrix has been recently described in detail.…”

“…38,39 The poly(ethylene glycol) (PEG) chain in the LTL is a spacer that extends the functional ligand from the hydrophobic PP surface to the hydrophilic mobile phase. 38 This simple LTL functionalization method opens the door for the use of PP C-CP fibers as stationary phase for affinity separations. The PEG-lipids are commercially available with a variety of functional ligands (R-groups in Fig.…”

Polyethylenimine modified poly(ethylene terephthalate) capillary channeled-polymer fibers for anion exchange chromatography of proteins

“…Likewise, a completely new family of ligands has been developed based on the high affinity for aliphatic chains for the hydrophobic PP fiber surfaces. Lipid tethered ligands (LTLs) having a variety of capture head groups readily adsorb at room temperature, and are immune from elution/leakage from the column under any sort of conditions common to biomolecule separations [14][15][16][17]. An example of covalent coupling involves the use of ethylenediamine as a means of activating PET C-CP fibers, yielding a surface rich with primary amines.…”

Overload Effects in Reversed Phase Protein Separations using Capillary‐Channeled Polymer Fiber Columns

“…These 30‐ to 50‐μm diameter polymer fibers are made in a melt‐spin process by extrusion from PP, PET, and nylon 6 base materials through an orifice with the desired shape. Fiber surfaces can be modified on‐column through simple adsorption or covalent ligand coupling to provide greater selectivity . The close, parallel packing of the eight‐channeled fibers provides a unique transport medium.…”