Competitive Adsorption of Three Human Plasma Proteins onto Sulfhydryl-to-sulfonate Gradient Surfaces

Abstract

Competitive adsorption of three human plasma proteins: albumin (HSA), fibrinogen (Fgn), and immunoglobulin G (IgG) from their ternary solution mixtures onto a sulfhydryl-to-sulfonate gradient surface was investigated using spatially-resolved total internal reflection fluorescence (TIRF) and autoradiography. The concentration of each protein in the ternary solution mixture was kept at an equivalent of 1/100 of its physiological concentration in blood plasma. The three proteins displayed different adsorption and desorption characteristics. Each protein adsorbed less to the sulfonate region than to the sulfhydryl region of the gradient. The adsorption-desorption kinetics revealed large differences in the adsorption and desorption rates of three proteins. By fitting the experimental data to a simple model of competitive protein adsorption, the affinity of each protein to the surface at the gradient center position was ranked as: Fgn > HSA ≫ IgG. Competitive exchange of adsorbed proteins was related to the magnitude of desorption rate constants. Such competitive adsorption of the three major human plasma proteins illustrates the complex dynamics of blood proteins – biomaterials interactions.

Bi-ligand surfaces with oriented and patterned protein for real-time tracking of cell migration

“…Chemical gradients were formed on the silanized silica surfaces using a previously developed controlled oxidation process [54–57]. The surface thiols were selectively oxidized by moving a mask over the surface in a controlled manner during exposure to UV light (290 nm) resulting in a gradient of reactive surface thiols and a counter gradient of nonreactive sulfonates on the surface.…”

Two surface gradients of polyethylene glycol for a reduction in protein adsorption

“…Both adsorbed amount profiles approached zero adsorption towards the PEG side of the gradient while the adsorbed amounts at the sulfonate region were at the levels comparable to previously reported data. 31 Figure 8(d) shows two HSA adsorption profiles taken in different experiments illustrating how reproducible PEG gradients were when prepared by the oxidation method.…”

“…If the protein desorption rate is very slow, the flux of protein molecules to the surface (J P ) can be used to calibrate the fluorescence. 31,35 When protein solution flows through a channel with a rectangular cross-section the flux of protein molecules to the surface is: 1 where D P is the diffusion coefficient of the protein, c p is the concentration of protein in solution, [Γ(4/3)] is the gamma function of 4/3, l is the distance along the flow channel, b is the channel thickness, w is the channel width, and q is the volumetric flow rate of the protein solution. 35 In a transport-limited regime and in the absence of fast desorption, initial J P from Equation 1 is approximately equal to the adsorption rate dΓ/dt, where Γ is the adsorbed amount (units: mass/area).…”

“…Adsorbed amounts of FGN and HSA obtained by this method agreed with literature data for sulfhydryl-sulfonate gradients as verified by autoradiography. 31 …”

“…The second 'oxidation' method generated the gradient through a gradual oxidation of reactive surface sulfhydryl species into sulfonate moieties as previously described 14,31 ( Figure 3). A uniform sulfhydryl surface was placed into a slide holder and the central 1 cm region of the fused silica slide was gradually exposed to UV light (ELC-4000, Electrolite Corp) by the linear translation of a mask at a constant rate of 0·25 cm/min for 4 min.…”