In this comparative study, the heparinisation of titanium dioxide substrates by means of the spacer molecules APMS, Di- and Triamino-APMS was investigated with regard to the biological activity of the immobilised drug and the adsorption of the extracellular plasma protein fibrinogen by means of the QCM-D technique to obtain a first impression of the biocompatibility for a possible in vivo application. The remaining activity of heparin was found to be highest for the covalent attachment with Triamino-APMS as coupling agent due to the long chain of this spacer molecule and therefore the highest mobility of the drug, which allows a better interaction of heparin with ATIII for inhibition of blood clotting. Furthermore, the adsorption of fibrinogen on the differently heparinised surfaces in real time demonstrated that with longer spacer chains and accordingly increasing number of secondary amino groups the ΔD/Δf ratios become higher, which is also associated with a less pronounced denaturation of the protein and thus possibly better biocompatible properties of the substrates in contact with a biosystem.
The author(s) declare that they have no competing interests.
DT took part in conceiving of the study, carried out the experimental work and drafted parts of the manuscript. RT participated in the design of the study. UG took part in conceiving of the study and drafted parts of the manuscript. All authors read and approved the final manuscript.
The authors would like to thank the Deutsche Forschungsgemeinschaft (DFG) who funded the study within the DFG priority program SP1100 (DFG Th438/17-1-3).