Rapid test for platelet viability relying on a quartz crystal microbalance assay

Sensing systems provide a fast and cost-effective way to monitor health parameters and can thus help medical personnel to ensure optimal care for patients. In this study, we present a sensor based on quartz crystal microbalances (QCMs) with bare, non-modified gold electrodes to monitor viability of platelets in stored platelet concentrates used in transfusion medicine. The system is useful to determine cell viability both in static and continuous flow experiments. Sensor responses correlate with platelet viability: viable cells have the ability to activate and aggregate and, thus, firmly attach to the QCM gold surface, in turn causing high frequency shifts due to a change in viscoelastic properties. For instance, on the fifth day of storage, platelet samples led to QCM frequency shifts less than 40% of the signal obtained from the fresh concentrate. Sensor results correlate well with a resazurin-based fluorescence viability assay. This also correlates with optical and atomic force microscopy (AFM) images that reveal changes in platelet morphology during the storage period, namely cessation of extensive pseudopodia formation and platelet spreading. Platelet size in solution significantly increased during storage, most likely due to a pH drop in the medium. The straightforward system is thus in principle useful to detect storage lesions and viability of platelets directly before transfusion. Quartz crystal microbalance (QCM) measurements allow for assessing platelet viability directly in thrombocyte concentrates. The sensor signals correlate well with fluorescence assays and thus in principle constitute a rapid tool for quality control.