Human serum albumin adsorption on poly[(glycidyl methacrylate)-co-(methyl methacrylate)] beads modified with a spacer-arm-attachedL-histidine ligand

Protein Adsorption onto Modified Porous Silica by Single and Binary Human Serum Protein Solutions

Typical porous silica (SBA-15) has been modified with pore expander agent (1,3,5-trimethylbenzene) and fluoride-species to diminish the length of the channels to obtain materials with different textural properties, varying the Si/Zr molar ratio between 20 and 5. These porous materials were characterized by X-ray Diffraction (XRD), N2 adsorption/desorption isotherms at -196 °C and X-ray Photoelectron Spectroscopy (XPS), obtaining adsorbent with a surface area between 420-337 m2 g-1 and an average pore diameter with a maximum between 20-25 nm. These materials were studied in the adsorption of human blood serum proteins (human serum albumin-HSA and immunoglobulin G-IgG). Generally, the incorporation of small proportions was favorable for proteins adsorption. The adsorption data revealed that the maximum adsorption capacity was reached close to the pI. The batch purification experiments in binary human serum solutions showed that Si sample has considerable adsorption for IgG while HSA adsorption is relatively low, so it is possible its separation.

Adsorption of albumin and sodium hyaluronate on UHMWPE: a QCM-D and AFM study

The biotribological properties of artificial joints, in particular the efficiency of the lubrication, strongly determine their lifetime. The most commonly used artificial joints combine a metallic or ceramic part articulating against a ultra high molecular weight polyethylene (UHMWPE) counterface, and are lubricated by the periprosthetic fluid. This fluid contains several macromolecules, namely albumin and sodium hyaluronate (NaHA), that are known to be involved in the lubrication process. There are several studies in the literature concerning the interaction of the referred macromolecules with ceramic or metallic prosthetic materials. However, to our knowledge, information about their binding to the polymeric surface is practically inexistent. The objective of this work is to contribute to clarify the role played by albumin and NaHA on the biolubrication process, through the investigation of their interaction with the UHMWPE surface. The study involves adsorption measurements using a quartz crystal microbalance with dissipation (QCM-D), the characterization of the adsorbed films by atomic force microscopy (AFM) and wettability determinations. Albumin was found to adsorb strongly and extensively to the polymer, while NaHA led to a very low adsorption. In both cases rigid films were obtained, but with different morphology and porosity. The high binding affinity of the protein to the polymer was demonstrated both by the results of the fittings to Langmuir and Freundlich models and by the values of the adhesion forces determined by AFM. In the simultaneous adsorption of albumin and NaHA, protein adsorption is predominant and determines the surface properties.