Blood protein repulsion after peptide entrapment in pendant polyethylene oxide layers

A number of sufficiently small peptides have been shown to integrate into polyethylene oxide (PEO) brush layers in accordance with their amphiphilicity and ordered structure. Those results have suggested that responsive drug delivery systems based on peptide-loaded PEO layers can be controlled by modulation of solution conditions and peptide amphiphilicity. However, the presence of entrapped peptide may compromise the protein repulsive character of the PEO layer, and in this way reduce the viability of a medical device coating based on such an approach. Nisin is a cationic, amphiphilic, and antimicrobial peptide that has been shown to integrate into PEO brush layers. In this work, the preferential location of fibrinogen at PEO-coated, nisin-loaded layers was investigated in nisin-fibrinogen sequential adsorption experiments using detection of fluorescein isothiocyanate labeled fibrinogen, detection of changes in zeta potential, and measurement of adsorption and elution kinetics by optical waveguide lightmode spectroscopy. Results from each technique indicate that the presence of entrapped nisin does not affect fibrinogen interaction with the PEO layer. In addition, entrapment of blood solutes within PEO layers contacted with 25% equine plasma in phosphate-buffered saline was reduced by the prior entrapment of nisin within the layer.