Study Of A SPR Biosensing Detection Method For Platelet Adhesion

With the development of the whole society, cardiovascular disease has become one of the major crises in human health. The morbidity of thrombotic disease, in particular, is very obvious. Thrombotic disease is a type of disease that related to the pathological thrombogenesis. One way to treat this disease is to prevent the thrombogenesis. Pharmacological mechanism of most antiplatelet agents is to inhibit the aggregation and adhesion of platelets. Due to the fact that biological effect of antiplatelet agents could differ in diverse patients, it is important to monitor this effect to find the optimal dose, which could reduce the thrombogenesis and bleeding of the special individual. So many kinds of methods and instruments to detect platelet function are widely used in the monitoring of antiplatelet therapy. But this monitoring is limited by some shortcomings of traditional platelet analyzers, such as operating complexity, time-consuming, low accuracy, high costs, label required, and so on. This paper applied surface plasmon resonance(SPR) sensing technique for the analysis of platelet, which could assess the changes of platelet function by measuring the adherence value, thus to monitor the biological effect of antiplatelet agents in individuals. Compared with the traditional platelet analyzer, this technique has the advantage of high accuracy, no label required, simple operation, high throghput, and so on.We firstly analyze the width and height of several channels using COMSOL simulation software. By analyzing the distribution of the bottom shear rate, we chose a group of channels that had the most uniformly distributed shear rate to complete the chip making. In this paper, we conducted the initial experiment on platelet adherence in the gaseous phase and the liquid phase, respectively. It shows that after flowing blood, surface refractive index and SPR angel increased, and the latter can be used to calculate the value of platelet adherence by calculating SPR angel increment. This means that SPR sensor can be used to assess platelet function with adhesion value as a referenced standard to quantitatively analyze the distribution of platelet in the channels, and also be used to conduct a precise assessment of any location in the channels. This method ensures high experimental repeatability. Multi-point analyzing method can achieve the effect that the traditional analysis is required to detect repeatability in one experiment. By comparing different detection conditions, the liquid phase has more advantages on platelet adherence.In the liquid phase, we detected the influence that different factors act on platelet. Those factors are shear rate and different protein matrices. It shows, within a certain range, platelet adherence increases by the increase of the shear rate. The peak point is 2.958ng/mm2 with shear rate of 500s-1. After that, platelet adherence decreases by the increase of shear rate. As for the matrix protein, platelet adherence value depends on collagen solution concentration, the greater the concentration, the more adherence value, but the structure of fibrin also affects the adhesion of platelet. Platelets have no reaction with serum protein because of its inertia.We also designed a dental channel to assess the distribution of platelet adherence as vessel stenosis in vivo. It shows, within low shear rate, the adherence values at any location of dental channel are higher than that of medium and high shear rate. With the increase of shear rate, numbers of platelet in the midstream of the channel are lower than that in the upper or lower stream.Finally, we applied aspirin of different concentration to human blood sample. The result shows more aspirin use induces more platelet adherence, which means the inhibition degree is proportional to aspirin used. Then we used adenosine diphosphate(ADP) to activate platelet so as to simulate the activated state of platelet in the patients with thrombotic disease. After adding aspirin of different concentrations, it shows that aspirin of low dose works very little to inhibit the adherence of platelet, and adherence value is still at a high level. When increasing the dose of aspirin, adherence value decreases and reaches a normal level. But when aspirin dose reaches too high, the adherence value will be below the normal level, which means the coagulation function of platelet is in dysfunction and the incidence of bleeding will be increased.