Amount protein adsorbed

Figure 4.1 Correlation between total amount protein adsorbed and circulation half-life before plasma clearance of Uposomes administered intravenously in mice. Results are shown for liposomes containing SM PC GM1 (72 18 10) open square), PC CH (55 45) open triangle), PC CH plant PI (35 45 20) open circle), SM PC (4 1) filledtriangle), PC CH DOPA (35 45 20) (filled square), and PC CH DPG (35 45 20) filled circle).

These assumptions were confirmed by the electrophoresis study of the washed creams. Electrophoresis of purified fat globules is a convenient method to characterize and quantify proteins adsorbed at the oil-water interface [35]. Electrophoretic data indicate that no casein, nor whey proteins, were adsorbed at the surface of raw-milk fat globule. Upon homogenization, caseins adsorbed preferentially at the lipid-water interface. In this case, bound a-lactalbumin accounted for 16% of the total interfacial proteins. Heat treatment also induced the interaction of proteins with the fat globules. The amount of bound proteins (per mg of lipids) for heated raw milk was half that for homogenized milk. 

All the immobilisations were conducted under stirring conditions at room temperature, then the mixtures were centrifuged for 10 min at 5000 rpm and filtered. The fluorescence of the supernatant was analysed. After a washing treatment, the filtered solution have no evidenced the presence of free protein. The amount of protein adsorbed on the surface was calculated by difference from these protein content data. 

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. 

Figure 4c shows that the amount of adsorbed proteins is rapidly saturated within several minutes of exposing serum-containing medium to a surface. Albumin, the most abundant serum protein, was expected to preferentially adsorb onto the surfaces during early time points. Then, adsorbed albumin was expected to be displaced by cell adhesion proteins. To investigate the effect of preadsorbed albumin displacement on cell adhesion, SAMs were first exposed to albumin then, HUVECs suspended in a serum-supplemented medium were added [21, 42]. Very few cells adhered to hydrophobic SAMs that had been pretreated with albumin, due to the large interfacial tension between water and the hydrophobic surfactant-like surface. Albumin was infrequently displaced by the cell adhesive proteins Fn and Vn. One the other hand, HUVECs adhered well to hydrophilic SAM surfaces that had been preadsorbed with albumin. In that case, the preadsorbed albumin was readily displaced by cell adhesive proteins. 

Determine the amount of adsorbed protein on the particles by using a suitable protein assay technique, such as the bifunctional chelating agents (BCA) Protein Assay (Thermo Fisher). 

Permanence of Adsorption of BSA. By determining the total amount of protein adsorbed on the four sections (cf Fig. 1) of the glass slide (Table 1), it can be seen that within experimental error, that all the initially adsorbed BSA was accounted for... 

Table 7.1 Effect of xanthan (XG) and NaCl on oil-in-water emulsions (50 vol% com oil) made at pH = 7.0 with legume seed protein isolate (LSPI) as emulsifying agent total protein adsorbed (Tt), average droplet size c/32, and amount of LSPI adsorbed per unit area of surface (Ts). Data from Makri et al. (2005) with permission.

Wagner et al. [108] developed a PLS model to predict the amount of protein adsorbed in a metallic basis using time-of-flight SIMS (TOF-SIMS) spectra. Study of the multivariate models yielded insight into the surface chemistry and the mechanism for protein resistance of the coatings. The same group reported two other similar studies with satisfactory results [109,110]. 

Fig. 17. At low solution concentration, the protein has no neighbors on the surface and thus can optimally adapt to the surface, maximizing the number of binding interactions. At high solution concentration, any one adsorbed protein is immediately surrounded by neighbors, minimizing the probability that it can conformationally adapt to the interface. This behavior leads to the differences in adsorbed amount and adsorbed protein thickness (determined by ellipsometry), as discussed in the text...

In the case of adsorbents with high surface area, changes in protein bulk solution concentration before and after adsorption are usually large enough for independent determination of the amount of protein adsorbed, either via solution depletion meas-... 

In TIRF protein adsorption experiments, it is desirable to correlate the intensity of excited fluorescence with excess protein concentration at the interface. Such an adsorbed layer is often in equilibrium with bulk-nonadsorbed protein molecules which are also situated inside the evanescent volume and thus contributing to the overall fluorescence. Various calibration schemes were proposed, using external nonadsorbing standards40,154 , internal standard in a form of protein solution together with a type of evanescent energy distribution calculation 154), and independent calibration of protein surface excess 155). Once the collected fluorescence intensity is correlated with the amount of adsorbed protein, TIRF can be applied in the study of various interactions between surface and protein. 

ATR spectroscopy in the infrared has been used extensively in protein adsorption studies. Transmission IR spectra of a protein contain a wealth of conformational information. ATR-IR spectroscopy has been used to study protein adsorption from whole, flowing blood ex vivo 164). Fourier transform (FT) infrared spectra (ATR-FTIR) can be collected each 5-10 seconds165), thus making kinetic study of protein adsorption by IR possible 166). Interaction of protein with soft contact lens materials has been studied by ATR-FTIR 167). The ATR-IR method suffers from problems similar to TIRF there is no direct quantitation of the amount of protein adsorbed, although a scheme similar to the one used for intrinsic TIRF has been proposed 168) the depth of penetration is usually much larger than in any other evanescent method, i.e. up to 1000 nm water absorbs strongly in the infrared and can overwhelm the protein signal, even with spectral subtraction applied. 

The FRAP apparatus can also be used in a semi-quantitative manner to measure the surface concentration and subsequent competitive displacement of adsorbed labelled species, such as the fluorescent-labelled protein in the adsorbed layer of a/w or o/w thin films [10]. This can be achieved by focusing the low power 488 nm beam on the film and detection of the emitted fluorescence using the FRAP photon counting photomultiplier. The detected fluorescence signal is proportional to the amount of adsorbed protein at the interfaces of the thin film provided that the incident laser intensity is kept constant. Calculations have proved that the contributions from non-adsorbed protein molecules in the interlamellar region of the film are negligible [12],... 

The amount of adsorbed protein is initially high due to the high fat content (approx. 

In 1982, an azo-dye-containing copolymer of 2-hydroxymethyl methacrylate was used for modulation of lysozyme adsorption on polymer beads. The amount of the protein adsorbed on a microsphere decreased upon irradiation, but rather long... 

DNA has been used to modify the PSf membrane by blending and immobilizing DNA onto its surface [123,124]. PSf is one of the most important polymeric materials and is widely used in artificial and medical devices. However, when used as a hemodialysis hollow fiber, the blood compatibility of the PSf membrane is not adequate. The hydrophilicity of the DNA-modified surface increased, but the amount of adsorbed protein did not decrease significantly, which indicates that the DNA-modified membrane might have a better blood compatibility. 

The amount of BSA measured in an initial concentration range of 10 to 1000 mg/L adsorbed on Qzm dusts, is compared in Figure 3A with the amount of BSA adsorbed on A50. Qzm and A50 exhibit different affinities for BSA with increasing protein concentration the coverage on amorphous silica increases up to a value of 500 pg/rrr, and on quartz the amount of BSA adsorbed reaches 1500 pg/rrr. In both samples, the amount of BSA adsorbed does not reach the monolayer value (around 2 mg/m2), assuming that the protein adsorbs sideways-on. 

Figure 3. BSA adsorption on quartz and amorphous silica. Amount of protein adsorbed vs initial concentration of (a) commercial quartz and (b) amorphous sihca. B. FTIR spectra of (a) native BSA, (b) BSA adsorbed on amorphous sihca and (c) BSA adsorbed on quartz.

Figure 4. BSA adsorption on modified quartz dusts, amount of protein adsorbed vs initial concentration of Qzm ( ) Qzm outgassed at 800° C (V), silanized ( ) and treated with diluted HF (T) and pure quartz (O).

The reaction of the inhaled particles with endogenous molecules present in the pulmonary surfactant e.g. surfactant, antioxidant molecules and proteins may determine the fate of the particles in the early steps of the pathological process. Although the silica samples considered in the present work are very pure, with the SiC>2 content great then 98%, they strongly differ in surface properties. The observed different interaction of BSA with the dusts considered is a consequence of such variability. Since the response of macrophages to silica particles may be different depending on the amount of protein adsorbed, the in vivo and/or in vitro toxicity of the silica dusts may be affected by the different affinities for pulmonary surfactant proteins. 

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