Ellipsometry was used to study the effects of surface energetics
and temperature on the equilibrium adsorptive behavior exhibited by
β-lactoglobulin. β-Lactoglobulin isotherms at 25, 37, and 55°C were
constructed for this purpose. The surfaces of acrylic, polycarbonate,
polyester, glass, and #304 stainless steel were contacted with protein
solutions of varying...
Surface tension kinetics exhibited by selected stability mutants of T4 lysozyme at the air-water interface were monitored with DuNoüy tensiometry. Mutant lysozymes were produced by substitution of isoleucine at position 3 with cysteine, leucine, tryptophan and glycine. Each substitution resulted in an altered structural stability quantified by a change in...
The adsorption kinetics exhibited by selected charge mutants of T4 lysozyme at
silanized silica surfaces were monitored with in situ ellipsometry. Mutant lysozymes were
produced by substitution of lysine (Lys) with glutamic acid (Glu). Each substitution
resulted in a decrease in the net charge of the protein by 2 units....
The effect of pH and ionic strength on the equilibrium adsorptive
behavior of β-lactoglobulin onto hydrophobic and hydrophilic
silicon surfaces was studied using ellipsometry. Plots of amount
adsorbed (μg protein/cm²) as a function of protein concentration
(mg/ml) exhibited attainment of plateau values beyond a protein
concentration of 0.250 mg/ml. At...
Nisin, an amphiphilic, antimicrobial peptide, has been shown to integrate into the hydrophobic inner region of poly(ethylene oxide) (PEO) brush layers; however, the presence of integrated nisin may compromise the protein repulsive character of the PEO layer. In particular, the introduction of fibrinogen to nisin-loaded brush layers has been observed...
In this study the enzymatic activity of adsorbed Thermomonospora fusca E₅ and Trichoderma reesei CBHI cellulases were investigated using fluorescence techniques. In particular, cellulases were allowed to contact hydrophobic polystyrene surfaces under conditions of different solution concentrations, and adsorption times. Each of these variables is known to have a potential...
Adsorption kinetic data recorded for α-lactalbumin, β-casein, β-lactoglobulin, bovine serum albumin and lysozyme at silianized silica surfaces of low and high hydrophobicity, along with a simple model for adsorption and surfactant-mediated elution of protein, were used to analyze the removal of each protein by sodium dodecylsulfate (SDS) and dodecyltrimethylammonium bromide...
A more quantitative understanding of peptide entrapment and elution from otherwise protein-repellent polyethylene oxide (PEO) brush layers will provide direction for development of new strategies for drug storage and delivery. Here we describe criteria for peptide integration and structural change within the PEO brush, and discuss the reversibility of peptide...
The adsorption behavior of a human recombinant Factor VIII (rFVIII) in the presence of the nonionic, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock surfactant Pluronic® F-68 was evaluated by dynamic air-water tensiometry. Surface tension kinetics were recorded for F-68 in the absence of protein at concentrations ranging from 0 to 10,000...
The marked increase in surface-to-volume ratio associated with microscale devices for hemodialysis leads to problems with hemocompatibility and blood flow distribution that are more challenging to manage than those encountered at the conventional scale. In this work, stable surface modifications with pendant polyethylene oxide (PEO) chains were produced on polycarbonate...
A more quantitative understanding of peptide loading and release from polyethylene oxide (PEO) brush layers will provide direction for development of new strategies for drug storage and delivery. The antimicrobial peptide nisin shows potent activity against Gram-positive bacteria including the most prevalent implant-associated pathogens, its mechanism of action minimizes the...
The role of the nonionic surfactant Tween 80 on the behavior of the therapeutic recombinant protein Factor VIII (rFVIII) was investigated at solid/liquid and air/water interfaces. In order to provide a model system to compare results obtained for the complicated rFVIII-Tween system, a well-characterized globular protein lysozyme was used. The...
Interactions between proteins and contact surfaces can have
important implications in the food industry. Such interactions
contribute to the course of fouling of membrane surfaces and they
appear to mediate bacterial and spore adhesion to some degree as
well. In addition to protein and solution properties, interfacial
behavior is strongly...
While hydrophobic surfaces coated with the poly[ethylene oxide]-poly[propylene oxide]-poly[ethylene oxide] (PEO-PPO-PEO) surfactant Pluronic® F108 are highly resistant to plasma protein adsorption, the antimicrobial peptide nisin has been observed to adsorb in multilayer quantities at such surfaces, and the PEO chains themselves suggested to inhibit nisin exchange by blood proteins. But...
Nonionic surfactants are commonly used to stabilize proteins during upstream and downstream processing and drug formulation. Surfactants stabilize the proteins through two major mechanisms: (i) their preferential location at nearby interfaces, in this way precluding protein adsorption; and/or (ii) their association with protein into "complexes" that prevent proteins from interacting...
The surface tension kin'ti4tnd ste'dy state behavior exhibited by mixtures of selected
surfactants with a recombinant Factor VIII (rFVIII) were evaluated with automated
interfacial tensiometry. In particular, fresh solutions of rFVIII with different concentrations
of Tween 80, sodium dodecylsulfate (SDS), or dodecyltrimethylammonium bromide
(DTAB) were prepared and their surface tension...
Heparin was modified with adipic diliydrazide and covalently linked to surface-activated silica. Contact angle measurements were made to determine changes in surface at various stages of the derivatization. Xray photoelectron spectroscopy was used to analyze the elemental composition of the surface at each step of immobilizing heparin as well and...
The adsorption and elution of the antimicrobial peptide nisin at hydrophobic,
silanized silica surfaces coated with the poly[ethylene oxide]-poly[propylene oxide]-
poly[ethylene oxide] surfactant Pluronic® F108 was measured in situ, with ellipsometry.
While such layers are known to inhibit protein adsorption, nisin was observed to adsorb in
multilayer quantities, to an...
Adipic dihydrazide-modified heparin was prepared and
subsequently immobilized on surface-activated silica wafers. X-ray
photoelectron spectroscopy (XPS) was used to quantify the elemental
composition of the silica surface at each stage of activation and results
showed that successful immobilization had taken place. Contact angle
measurements were made to verify the high...