D-dimer Detection Based On QCM Immunosensor

D-Dimer is a kind of specific degradation product of cross-linked fibrin by the hydrolysis of plasmin, and reflects a global activation of blood coagulation and fibrinolysis related diseases, such as myocardial infarction, venous thrombus and tumour, etc., with important fuction of diagnosis, prediction and treatment. In recent years, main d-dimer analysis methodologies are with the disadvantages of high cost, complexity and time consuming, so it is imperative to find a way both inexpensive and brief. Quartz crystal microbalance (QCM) is a sensitive mass measuring instrument for the mass change on the surface based on the piezoelectric effect of the quartz crystal. The QCM immunosensor is widely applied and researched in the areas of biomedicine, food security, environtology, chemical industry and national defense, because of its simple in device, convenient in manipulation, low in expense and high in sensitivity, and behave well in sensitivity and instantaneity.Based on the theory of detection of QCM, this report gives out a QCM immunosensor used for liquid phase detection, and self-assembly technique was used for the preparation of the bio-sensitive film for D-dimer detection, and different concentrations of D-dimer antigen were tested in the experiments. As the frequency response was low, a sandwich assay was established, and used gold nanoparticle (AuNP) conjugated anti-D-dimer antibody to enhance the response and the sensitivity successfully, and got the relational function between frequency response and D-dimer concentration. Afterwards, the experimental installation was improved aiming at the issues found in the earlier experiments, and lower the limit of detection (LOD) of the system. Finally, the immunosensor could detect the D-dimer with the concentration ranges from10to5000μg/L, with the LOD of10μg/L, and the response of QCM is observed to be linearly relative to the D-dimer concentration in the range of10ug/L to1000μg/L, which covers the point around200μg/L, which is used clinically as the point to tell whether sick or not. And at last, the experiments using the serum were done, and concordant results with the former experiments was got.