We measured adsorption of bovine serum albumin (BSA) and fibrinogen (Fg) onto six distinct bare and dextran- and hyaluronate-modified silicon surfaces created using two dextran grafting densities and three hyaluronic acid (HA) sodium salts derived from human umbilical cord, rooster comb and streptococcus zooepidemicus. Film thickness and surface morphology depended on HA molecular weight and concentration. BSA coverage was enhanced on surfaces upon competitive adsorption of BSA:Fg mixtures. Dextranization differentially reduced protein adsorption onto surfaces based on oxidation state. Hyaluronization was demonstrated to provide the greatest resistance to protein coverage, equivalent to that of the most resistant dextranized surface. Resistance to protein adsorption was independent of the type of hyaluronic acid utilized. With changing bulk protein concentration from 20 to 40 µg ml−1 for each species, Fg coverage on silicon increased by 4×, whereas both BSA and Fg adsorption on dextran and HA were far less dependent of protein bulk concentration.
The initial response of blood exposed to an artificial surface is the adsorption of blood proteins that triggers a number of biological reactions such as inflammation and blood coagulation. Competitive protein adsorption plays a key role in the hemocompatibility of the surface. The synthesis of nonfouling surfaces is therefore one of the major prerequisites for devices for biomedical applications. Polysaccharides are the main components of the endothelial cell glycocalyx and have the ability to reduce nonspecific protein adsorption and cell adhesion and, therefore, are generally coupled with a wide variety of surfaces to improve their biocompatibility. We have developed a procedure for covalently binding dextran and sodium hyaluronate (HA) on silicon wafers and we have been able to achieve a high level of control over the surface properties of the coatings. In the present research effort we focus on a detailed investigation of competitive bovine serum albumin (BSA) and bovine fibrinogen (Fg) adsorption on dextran-and HA-modified silicon surfaces. Polysaccharide based biomimetic layers preferentially adsorb BSA and, in general, strongly suppress protein adsorption with respect to bare silicon and APTES-activated silicon surfaces used as control. ABSTRACTThe initial response of blood exposed to an artificial surface is the adsorption of blood proteins that triggers a number of biological reactions such as inflammation and blood coagulation. Competitive protein adsorption plays a key role in the hemocompatibility of the surface. The synthesis of nonfouling surfaces is therefore one of the major prerequisites for devices for biomedical applications. Polysaccharides are the main components of the endothelial cell glycocalyx and have the ability to reduce nonspecific protein adsorption and cell adhesion and, therefore, are generally coupled with a wide variety of surfaces to improve their biocompatibility. We have developed a procedure for covalently binding dextran and sodium hyaluronate (HA) on silicon wafers and we have been able to achieve a high level of control over the surface properties of the coatings. In the present research effort we focus on a detailed investigation of competitive bovine serum albumin (BSA) and bovine fibrinogen (Fg) adsorption on dextran-and HA-modified silicon surfaces. Polysaccharide based biomimetic layers preferentially adsorb BSA and, in general, strongly suppress protein adsorption with respect to bare silicon and APTES-activated silicon surfaces used as control.
Suspension testing is a standard way of characterizing the effectiveness of dispersants in wet or dry formulations. In a suspensibility test, a measured amount of material is diluted in hard water and given a specified amount of time to settle. The settled material is recovered and used to calculate the amount of material that remained suspended, yielding a suspension percentage. Different organizations use slightly different methods to conduct this characterization, and there are few studies which allow the experimentalist to correlate results between methods. The objective of this work is to compare two standard suspension tests, ASTM and CIPAC (Collaborative International Pesticides Analytical Council) and determine their correlation, if one exists. While similar, the methods vary by a few factors including the initial volume fraction of the material and the means of recovering the settled material. Several formulations of copper (II) hydroxide, dispersed with varying amounts of acrylic polymer, were dried and sieved into granule solids and powder solids. Suspension properties were tested using both methods. Resultant suspension percentages for each formula were charted, CIPAC results versus ASTM results. The coefficient of determination (R2) for the suspension percentages of the granule and powder solids was found to be 0.976 and 0.984, respectively. The granular solids showed a one-to-one relationship (slope=1) between results generated by these methods while the powder solids did not, y=0.56+0.37. The driver for this skew may be due to different particle volume fractions between the tests, a parameter which has the potential to affect viscosity in a predictable manner and which is represented mathematically by the Krieger-Dougherty equation.
Concentrated aqueous emulsions, or EWs, are the dispersion of a water insoluble organic liquid into water. The formulation is achieved through the use of polymeric surfactants, which provide multiple anchoring points and steric stabilization to prevent coalescence. Formation of the EW is mechanically driven, requiring high-shear processing to reduce particle size and attain a stable formulation. In this study, the relationship between processing shear time, particle size, and stability was examined. Samples were prepared using a high hydrophile/lipophile balance (HLB) polymer (butyl block copolymer) paired with a low HLB polymer (nonionic block or random copolymer), varying polymer types and polymer ratios. Shear was applied for 10 min to 40 min. Emulsion dilution stability (ASTM E1116-98), particle size distribution (Malvern Mastersizer), and high temperature stability were used to characterize the samples. It was found that particle size decreased as shear input was increased, reaching an optimum after 25 min to 30 min of shear, depending on the polymer pair used. All samples performed similarly in dilution stability showing improved performance after 10 min of shear. After 1 month at 54°C, all samples showed no separation and demonstrated similar dilution performance, however, D90 values dropped significantly (>20 %) in samples with less than 20 min of shear, whereas samples receiving a minimum of 20 min to 30 min of shear showed decreases in D90 around 10 %. A likely explanation for the decreases in D90 observed after elevated temperature storage is that the addition of heat energy drove the particle surface area toward equilibrium according to the equation ΔA=W/γ, where ΔA is change in surface area, W is work, and γ is interfacial tension
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.