A Quartz Crystal Microbalance enables the detection of mass variation by measuring the change in frequency of a quartz crystal resonator (the sensor). When molecules bind to the surface, the thickness of the crystal changes and this translates into a drop in frequency. The device can be used for example to study molecular interactions between proteins and other molecules such as proteins or DNA and also living cells. Ligand-analyte interactions can be measured by functionalizing the sensor surface via ligand binding.
What are the sample requirements?
- Sample volume of the measuring cell is about 30-40 µl.
- For static state measurements, around 100 µl is needed to exchange the liquid inside the cell.
- Protein concentrations of around 1 mg/ml is used for surface functionalization with the ligand.
- Analyte concentration can be much lower, e.g. around 0.1 mg/ml.
What other specific considerations are relevant?
- Purity of the ligand (molecule attached to the sensor chip) should be as high as possible, to prevent unspecific binding.
- Knowing the molecular weight of the analyte is important since the sensor detects the changes of mass on the surface
- If possible, viscous buffers should be avoided as they interfere with the QCM sensor.
- Buffers and samples should withstand degassing by vacuum.
Partners offering this technique
MOSBRI reference partner site for this technique: