Immobilization, Hybridization and Amperometric Detection of DNA Sensor Using Quartz Crystal Microbalance

Abstract

A synthesized 21-mer single-stranded DNA (ssDNA) was covalently immobilized onto a self-assembled aminoethanethiol monolayer modified gold electrode onto quartz crystal microbalance (QCM). The covalently immobilized ssDNA was hybridized with complementary ssDNA. The interaction between surface-immobilized ssDNA and complementary 21-mer DNA in solution was also examined. Each step was followed by monitoring changes in the QCM frequency over time. From the results, the measured frequency change was about 256 Hz, 160 Hz and 141 Hz, respectively. As a result, the adsorption mass was about 273 ng/cm2, 171 ng/cm2 and 151 ng/cm2, according to the Sauerbrey equation. Also, PBS with pH 7.0 was selected as a supporting electrolyte to achieve maximum sensitivity and good bioactivity. The anodic peak current was linearly related to the concentrations between 1 x 10(-5) and 9 x 10(-5) M with a detection limit of 1.0 x 10(-6) M.

A survey of the 2006–2009 quartz crystal microbalance biosensor literature

“…A number of publications describe the improvement of existing methods or development of new methods for the immobilization of RNA or DNA. These consisted of covalent immobilization (Lee et al ., 2008a; Razumovitch et al , 2009; Sato et al , 2009) including a photochemical method (Nakano et al , 2006), polycationic surfaces (Rawle et al , 2007; Yang et al , 2008a), inclusion in a layer‐by‐layer self‐assembly system (Sultan et al , 2009), natural organic matter (Nguyen and Chen, 2007; Nguyen and Elimelech, 2007a), adsorption directly to quartz (Nguyen and Elimelech, 2007b) and the use of biotinylated DNA on streptavidin (Yamasaki et al , 2007). Surface morphology was shown to play an important role, leading to a three‐ to five‐fold better sensitivity in an DNA detection assay where nanogold ‘hollow’ spheres where used instead of a flat gold surface (Lu et al ., 2007).…”