Development of a quartz crystal microbalance biosensor for cardiovascular marker detection

Abstract

Cardiac Troponin T (cTnT) detection is drawing a great interest due to its role in myocardial infarction diagnosis. In this study, we report relatively two new techniques to detect cTnT. First is by using quartz crystal microbalance (QCM) sensor. A sensitive detection is achieved by introducing QCM surface with a carboxylic polyvinyl chroride (PVC-COOH) immobilization layer. The surface morphologies of this polymer film under varied deposition thickness have been investigated by a field-emission scanning electron microscopy (FE-SEM) and an atomic force microscopy (AFM). The cTnT detection result from a modified QCM surface can be obtained within a short response time by a direct detection of the immuno-reaction and a direct conversion of mass accumulation into a frequency shift, representing a measurable electrical signal. The relationship between the cTnT concentration and the response current from the QCM sensor shows the detectability at the concentration of cTnT as low as 5 ng/ml. The second technique of cTnT detection is developed using surface enhanced Raman substrate (SERS). In latter technique, the nanostructure of silver film is fabricated for detection of troponin T protein by recording the shift in laser excitation wavelength due to vibrational modulation of specimens. These results suggest that both developed techniques for cTnT sensor may be a promising tool for future research as well as clinical diagnostics for the risk evaluation for cardiovascular diseases related to elevated cTnT levels.