Although SPR based research instruments are now on the The concentration of heparin, an anticoagulant in blood, is usumarket (e.g., Pharmacia, Anachem), the full potential of the ally inferred from clotting type assay, which determines a parametechnique in analyzing different binding processes has only ter related to the heparin activity. Because of the heterogeneity of begun to be explored. In this paper the use of SPR to deterheparin, however, it is desirable to monitor the absolute concentramine heparin is investigated.
tion of heparin directly in the clinical range of 0-2 U/ml. Surface
Heparin is known as one of the most powerful anticoaguplasmon resonance (SPR) provides a optical direct method of lants and it is therefore routinely used before and during monitoring binding events. Gold films, as required for SPR, were surgery. It also has a number of other pharmacological propmodified with protamine; the immoblized protamine interacts electrostatically with heparin so that the heparin adsorption is depen-erties, for example, it localizes various growth factors and dent on the absolute concentration. The ''thickness'' of the immoenhances their stability and activity (9), in the presence of bilized protamine layer determined the linear range of the sensor's ceratin steroids heparin can inhibit angiogenesis (10), and response and the sensitivity. Less densely packed layers of protheparin binds to, activiates, or inhibits a number of enzymes amine showed a lower detection limit for heparin, suggesting a and proteins (11). It also has a potential as a drug for the mixing of the heparin into the incomplete protamine layer. On the treatment of atherosclerosis since it causes the release of other hand, thicker, denser protamine layers did not show a low lipoprotein lipase from blood vessel walls and therefore limconcentration sensitivity to heparin although their maximum hepits the uptake of cholesterol rich lipoproteins (11).
arin binding capacity was increased. It was shown that the linear
Because of its many pharmacological properties heparin response range of the protamine modified SPR device to heparin could be modulated by altering both the protamine loading and treatment ought to be strictly monitored during administraits method of immobilization.