A Quartz Crystal Microbalance (QCM) Study of Single-Strand DNA Hybridization and Hydrolytic Cleavage

The use of a quartz crystal microbalance (QCM) for monitorin g in situ the immobilization of singlestrand DNA marked with mercaptol group at the 5'-end on the surface of a gold-filled 7.995 MHz AT-cut quartz crystal by Au–S bond with the self-assembly technique is reported. The hybridization of ssDNA with complementary 10-mer ODN and 8-mer ODN is described. The QCM was also employed to analyze DNA cleavage by cerium(IV) ions under moderate conditions. The results showed that the QCM, which is capable of sensitive measurement, was able to investigate the immobilization, hybridization, and cleavage of ssDNA in situ. The cerium(IV) ions produced no cleavage in double-strand DNA; they were, however, able to hydrolyze singlestrand DNA. Thus, the hydrolytic cleavage of ssDNA at a specific site could be ensured by protective hybridization.