Novel Differential Surface Stress Sensor for Detection of DNA Hybridization

A fiber optic coupled interferometric system designed to measure differential surface stress induced by DNA hybridization of (dA)₃₀ single-stranded DNA (ssDNA) with complementary (dT)₃₀ ssDNA in aqueous environment. The sensing system is amenable to miniaturize into a single MEMS-chip and performed direct detection of nanomechanical response of conformational change and the corresponding charge transduction during molecular adsorption. The static deflection of functionalized sensing cantilever respect to reference cantilever which passivated from additional target molecules converts into a surface stress change for quantitative analysis. The measured surface stress changes were turned to be 40 to 110 mN/m for the concentrations of 0.1 to 1.0 μM of target molecules associated with the dissociation constant (K_d) of 168 nM. X-ray photoelectron spectroscopy (XPS) analysis and noncomplementary experiments were also considered for the validity and reliability of the system.