Monitoring the drown-out crystallization of sodium chloride on a DNA-modified surface Original Research Article

The drown-out crystallization of sodium chloride is conducted on a DNA-modified quartz crystal microbalance (QCM). To investigate the crystallization behavior of NaCl on a DNA template, a thiol-modified DNA oligomer is self-assembled on a gold electrode of QCM. The resonant frequency shift and resonant resistance of the DNA-modified QCM are measured with the continuous injection of ethanol in the NaCl saturated solution, and compared with those of a bare QCM without any modification. F–R diagram is interpreted to analyze a detailed mechanism of the QCM response change for the crystallization. An atomic force microscope (AFM) technique is also used to confirm the procedure of the NaCl crystallization on the DNA template. From these results, it is found that the QCM sensor system could be applied to monitor the NaCl crystallization in the aqueous solution, and to detect a super-saturation point or degree.