Quartz crystal microbalance (QCM) measurements for rapidly predicting toxin induced cell death

Piezoelectric quartz systems have historically been used in analytical chemistry because their oscillating frequency value is sensitive and directly proportional to the crystal mass. Adding mass to the crystal decreases the frequency and reducing mass increases it. This mass sensing ability has resulted in the creation of a sensing device known as the quartz crystal microbalance (QCM). Since the QCM detects any mass coupled to its surface, it has been widely used as a label-free signal transduction platform for chemical sensor and biosensor designs. Recently, cell-based biosensors have been developed. In these devices, living cells are attached to the gold surface of the QCM and serve as the sensing element, where cellular mass and viscoelastic properties affect the oscillation frequency of the crystal. The advantage of cells as the sensing element is that they possess a wide range of intelligent system properties resulting from the interplay of their integral membrane receptor-cytoskeletal-nuclear membrane systems to alter their mass distribution or viscoelastic properties due to external (i.e. toxins) or internal (i.e. mitochondria activity) signals. Thus, cells can detect a wide variety of changes in their environment, from individual molecules to more complex alterations. These intelligent properties can be exploited when cells are used as biosensor detection elements.;In a series of studies developing cell-based biosensors, we can detect effects of small molecules that affect specific aspects of the cells. Advantages of live cell biosensors are that they measure continuously in real time. The unique attributes of QCM cell-based sensors allow them to detect agents in an environment, such as engineered nanomaterials (ENMs). Because the QCM measures a direct effect of the nanomaterial on living cells this avoids complications of ENMs interference with reporters in assays. The output is gathered continuously so unique cellular response information, such as brief transient exposures are detected and the kinetics of cell stress and recovery can be detected.;The use of a mass measuring device incorporating living cells as the sensing component can therefore provide important new response information and overcome inherent confounding issues of conventional toxicity testing methods.