Surface protein adsorption behavior

When cells are suspended in a biological fluid or culture medium, both serum proteins and cells interact with the surface substrate. Serum protein adsorption behavior on SAMs has been examined with various analytical methods, including SPR [58-61], ellipsometry [13, 62, 63], and quartz QCM [64—66]. These methods allow in situ, highly sensitive detection of protein adsorption without any fluorescence or radioisotope labeling. SPR and QCM are compatible with SAMs that comprise alkanethiols. In our laboratory, we employed SPR to monitor protein adsorption on SAMs. 

The surface properties of the protein molecules, especially hydro-phobicity, as well as the degree of the sorbent surface hydropho-bicity, strongly affect the protein adsorption behavior. Calculated... 

An understanding of protein adsorption behavior is applicable in numerous fields including blood-synthetic materials interfaces, macromolec-ular-rnembrane interactions, receptor interactions, enzyme engineering, adhesion, and protein separation on chromatographic supports. Many methods have evolved to study interfacial adsorption, but no single independent method seems adequate. The ideal technique should produce quantitative, real-time, in situ data concerning the amount, activity, and conformation of proteins adsorbed on well-characterized surfaces. All adsorption techniques are approximations to this optimum. 

One might speculate on a number of chemical and physical factors that govern protein adsorption behavior. Previous experiments point to the importance of hydrophilicity as an influential factor (6), but this is certainly not the sole factor. In this polymer system, hydrophilicity (as governed by the surface concentration of HEM A) increases linearly with the bulk HEM A composition (11). The surface of a protein which is also soluble in aqueous media is probably of a polar nature. If protein adsorption could be characterized by polar interactions, then an adsorption trend that would parallel the... 

The stmctural and conformational analysis of proteins adsorbed to solid surfaces is difficult because most common analytical methods are not compatible with the presence of the interacting solids. With recent developments in instrumentation and techniques, our understanding of protein adsorption behavior has improved considerably [4, 14]. The most commonly used techniques include attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), radiolabeling techniques, immunofluorescence enzyme-linked immunosorbent assay (ELISA), ellipsometry, circular dichroism (CD) spectroscopy, surface plasmon resonance (SPR), and amide HX with nuclear magnetic resonance (NMR). Atomic force microscopy (AFM) and scanning... 

Protein-adsorption behavior tvas also investigated by in situ spectroscopic ellips-ometry using a rotating compensator apparatus [56]. A fixed angle of incidence of 75° tvas used over a spectrum range of 191 to 1690 nm. The refractive indices of the polymer and the adsorbed protein layer as transparent materials were described using the Cauchy relationship. The thickness (d) and refractive index (n) of the adsorbed protein determined were used to calculate the surface concentration of protein (F) using De Feijter s formula ... 

The goal in this work was to lay out a model complex enough to describe protein adsorptive behavior at hydrophobic solid-water interfaces, but not so intricate as to lose track of surface and molecular property influences on the observed phenomena. 

One should be very cautious about explaining protein adsorption behavior on hydrophilie surfaces the relatively higher value of for jS-easein on the hydrophilie surfaee may be... 

We examined protein adsorption to SAMs that carried four different functional groups [42] and mixed SAMs with different wettabilities [21], Large amounts of serum proteins adsorbed to all these SAMs, but the different surface functional groups greatly affected cell adhesion behavior (Figs. 2 and 3). Thus, the amount of adsorbed proteins did not correlate with the degree of cell adhesion to SAMs. 

It has been known that adsorption kinetics and/or thermodynamics of proteins depend on the electric or electrochemical properties of solid supports on which the proteins are adsorbed. This has led us to elucidate the effects of electrode potential on the adsorption behavior of avidin on the electrode surface. For this purpose, the electrode potential of a Pt electrode was varied systematically in the range of -0.5-+2.0 V in an avidin solution (pH 7.4). Although the data was somewhat scattered, a general trend was observed that the adsorption of avidin is suppressed by the application of a positive potential (+1.0-+2.0 V). This may be originating from the fact that avidin is a basic protein and has net positive charges in the solution of neutral pH. In the potential range tested, no significant acceleration in the adsorption was induced. 

The bell-shape-profile concept for protein adsorption may be a useful guideline for researchers when they consider the adsorptive behavior of proteins on polymers with different degrees of hydrophilicity. As will be discussed in later Sect. (2.3), when material surfaces carry ionic groups, the contribution from... 

From the experiments it is clear that poly electrolyte is adsorbed on the surface of the black lipid film. This applies both to the experiments with gelatin and bovine serum albumin, which gave no decrease of film resistance, and to the experiments with bovine erythrocyte ghost protein and polyphosphate. The adsorption of protein on the phospholipid-water interface may be controlled independently by investigating the electrophoretic behavior of emulsion droplets, stabilized by phospholipid, in a protein solution, as a function of pH. In this way Haydon (3) established protein adsorption on the phospholipid-water interface. If the high resistance (107 ohms per sq. cm.) of black lipid films is to be ascribed to the continuous layer of hydrocarbon chains in the interior of the film, as is generally done, an increase in film conductivity is not expected from adsorption without penetration. 

Fig. 20. Schematic adsorption isotherms with a constant surface site concentration ([A]s in Fig. 12 is here constant), but with adsorption time as a variable. At very short times, adsorption is diffusion controlled. At short times, the protein has insufficient time to conformationally adjust to the interface, thus adsorption can be reversible and of the Langmuir type. At longer times, conformational adjustments begin leading to the commonly observed semi- orir-reversible behavior of protein adsorption. Other nomenclature same as Fig. 12...

---