Immunospecific analysis of in vitro and ex vivo surface-immobilized protein complex

Biomaterials used for blood contacting devices are inherently thrombogenic. Antithrombotic agents can be used as surface modifiers on biomaterials to reduce thrombus formation on the surface and to maintain device efficacy. For quality control and to assess the effectiveness of immobilization strategies, it is necessary to quantify the surface-immobilized antithrombotic agent directly. There are limited methods that allow direct quantification on device surfaces such as catheters. In this study, an enzyme immunoassay (EIA) has been developed to measure the density of a synthetic antithrombin-heparin (ATH) covalent complex immobilized on a catheter surface. The distribution of the immobilized ATH was further characterized by an immunohistochemical assay. This analyte-specific EIA is relatively simple and has high throughput, thus providing a tool for quantitative analysis of biomaterial surface modifications. These methods may be further modified to evaluate plasma proteins adsorbed and immobilized on various biomaterial surfaces of complex shapes, with a range of bioactive functionalities, as well as to assess conformational changes of proteins using specific antibodies.