Characterization of heparin surfaces using photoelectron spectroscopy and quartz crystal microbalance.

In order to gain insight into the molecular structure of a new heparin surface (Corline heparin surface, CHS), quartz crystal microbalance dissipation (QCM-D) and photoelectron spectroscopy (PES) were used. Two surfaces, with different surface thickness and surface concentration of heparin, were compared. QCM-D measurements provided information on the thickness of the two different heparin surfaces and confirmed that the process of formation of the two layers were virtually identical. PES showed that the thicker coating resulted in complete coverage of the substrate, whereas with the thinner coating Fe signals originating from the stainless steel substrate could be detected. Information of the molecular surface structure of the heparin coatings could be derived from the ratios at different photon energies between S2p signals from sulfonate groups in heparin and disulfide groups originating from a cross-linking unit in the heparin conjugate.