Adsorption kinetics and mechanical properties of thiol-modified DNA-oligos on gold investigated by microcantilever sensors

R. Marie, H. Jensenius, J. Thaysen, C.B. Christensen and A. Boisen

Mikroelektronik Centret, Technical University of Denmark, bldg. 345e, DK-2800 Lyngby, Denmark

Microcantilever-based sensors are suitable for quantitative and qualitative studies of self-assembling processes. Using microcantilever-based sensors with integrated read-out, we demonstrate in situ quantitative studies of surface stress formation during self-assembly of a 25-mer thiol-modified DNA-oligo layer on gold.
The adsorption and thus the output signal of the sensor follow an isotherm adsorption model. Based on the concentration dependency of the calculated adsorption rate constants the adsorption free energy is found to be -32.4 kJ/mol. Unspecific adsorption of DNA has also been observed and distinguished from the thiol specific adsorption. XPS measurements, AFM imaging and investigations by DNA array techniques support these interpretations.
Furthermore, we will present the results of DNA-oligos adsorption performed in a microcantilever chip which allows five simultaneous measurements in a microchannel.