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Abstract

During vaccine production it is very difficult to get up-to-date information of the progress of cultivation. The common detections methods such as euraminidase assays, ELISA or the agglomeration properties measurement of erythrocytes can only be conducted offline and require substantial time and costs. To minimize the amount of work and time, a micro sensor system based on a Quartz Crystal Microbalance (QCM) embedded in the fluid system (Fig. 1) and with a special surface-coating was designed to quantify influenza viruses in a culture broth. The QCM detection process consists of measuring a direct frequency shift (Δf) due to a mass deposition (Δm) of an analyte on the surface [A, B], therefore allowing operation without expensive markers. To take advantage of these properties a special Lectin (Euonymus Europaeus Lectin), which proved its affinity to human Influenza A (Puerto Rico /8/34) (H1N1) [C], is bound to the surface of the quartz electrode. The Lectin functions as a detection layer and specifically binds to influenza viruses, whereby the virus concentration in a solution, e.g. the filtrated culture broth, can be measured via the frequency drop over time. In figure 2 an example of a QCM measurement, containing solutions with different virus hemagglutination assay units (HAU), can be seen. The fast frequency shift occurs directly after contact of each dilution of the filtrated culture broth is an effect of viscosity and density of the solution. The true binding reaction can be observed a few seconds later at the second frequency shift. The lager the virus concentration the bigger the frequency drop per time. The quartz can be used for about four hours continuously with a hemagglutination assay unit (HAU) of 180 till first saturation effects can be measured. That means that roughly twenty single concentration measurements can be done with one single quartz.