Monitoring the Cellular Binding Events with Quartz Crystal Microbalance (QCM) Biosensors

Quartz crystal microbalance (QCM) biosensors have been demonstrated as noninvasive and label-free tools for cell based measurements. However, the complexity of biofilms composed of cells with the associated liquid environments is preventive towards forming explicit relationship between the added mass and the change in the frequency output signal. Therefore, the protocols of interface design (surface chemistry, interaction mechanism, and data acquisition), data interpretation, and device fabrication, all need to be finely refined in order to make these biosensors prevail in real life. Especially in the sense of deriving correct inferences from binding events, the fluidic effects (mostly visible in the form of damping resistance of QCM) should be quantitatively excluded from binding measurements. Such strategies can then track even the cellular interactions which are the basis of many physiological functions of life and can be built into smart functional devices for point of care diagnostics. This chapter provides technical details regarding these strategies with a focus on experimental details and procedures of the measurements of anti CD-20 antibody (Rituximab) interactions with B-Lymphoma cancer cells using the QCM method. In addition to a detailed description of specific interactions, we provide mechanisms of data interpretation and device development having potential application to other techniques.