Paper BI-TuP15
Competitive Protein Adsorption to Biomaterials and the Dependence on Protein Concentration

Tuesday, October 21, 2008, 6:30 pm, Room Hall D

Quantitative analysis of protein adsorption to artificial materials is of importance in evaluating the potential of biomaterials. Proteins have a central role in all living organisms and are present in basically all parts of the human body and the first thing to happen when an artificial material is introduced into a human body, or another biological system, is unspecific adsorption of proteins onto the surface of the material. Most studies on blood protein adsorption to polymer surfaces reported in the literature are performed from low concentration (≤1 mg/ml) single protein solutions. However, it is not evident that those results also are valid for protein adsorption from protein mixtures with high protein concentration (≥10 mg/ml). When biomaterials are introduced into a human body, thousands of different proteins, sometimes present in quite high concentrations, will come in contact with the material and there will be competitive protein adsorption on the surface of the material. By labelling proteins with different radioisotopes one can monitor the adsorption of several proteins onto surfaces simultaneously, and with this multi-labelling technique one can study competitive adsorption and use complex solutions such as human serum during adsorption experiments. Albumin and IgG (Immunoglobulin G) adsorption to both unmodified and modified PET (polyethylene terephthalate) surfaces from single protein solutions and human serum solutions has been monitored using radioactive labelling. The PET surfaces are modified through plasma polymerisation using the monomer DEGVE (diethylene glycol vinyl ether), which results in a more hydrophilic and anti-fouling surface than the PET surfaces. Results show that the detected anti-fouling quality of DEGVE surfaces is influenced by the concentration of the protein solution used. Albumin and IgG adsorption from human serum dilutions corresponding to 0.1% human serum shows that the albumin and IgG adsorption is significant lower on the DEGVE surface than on the PET surface, and that this antifouling characteristics of DEGVE surfaces can be stable for at least 24 hours. However, performing the same experiment, including the same rinsing procedure, with ≥10% human serum solutions, the detected albumin and IgG adsorption to DEGVE approaches the adsorption detected on unmodified PET. Thus, evaluation of biomaterials should be performed in an environment similar to the one the material is intended to operate in.