Specific binding DNA-based piezoelectric quartz crystal microbalance biosensor array for the study of NF-κB

NF-κB is a protein complex found in almost all animal cell types that act as a transcription factor. Conventional methods for the study of NF-κB, however, are time-consuming, and most require radioactive labeling. The aim of this study was to develop a rapid method to study NF-κB by use of a direct specific binding DNA-based biosensor based on a quartz crystal microbalance (QCM). A specific DNA probe was designed and modified by the sulfhydryl group on the 5′-Terminal to be immobilized on the gold coated surface of 10 MHz piezoelectric quartz crystal to construct the QCM biosensor to detect NF-κB. We made calibration curves after immobilization of probe at an optimal concentration and then evaluated the performance characteristics of the sensor with a series of tests. In addition, we measured clinical samples with both QCM sensor array and ELISA to assess the QCM sensor. Under optimal conditions, the response frequency of piezoelectric biosensor was linearly dependent on NF-κB concentrations in the range of 0.25 ng/μL to 50 ng/μL with relative standard deviation (RSD) of intra-assay and inter-assay less than 10%. The QCM system we designed has the advantages of being rapid, simple operation, label-free, cheap, sensitive and could be a useful supplement to commercial assay methods in the study of NF-κB, such as NF-κB binding, NF-κB quantitation, NF-κB identification and interaction between NF-κB and DNA.