| Summary: | Cytochrome c (cyt c) is an important indicator of cell apoptosis and can, therefore, be used for the diagnosis of cancer. We performed a comparative analysis of cyt c detection on the surface of lipid films or a monolayer of 11-mercaptoundecanoic acid (MUA) with immobilized specific or nonspecific DNA aptamers. A quartz crystal microbalance with dissipation monitoring (QCM-D) in a multiharmonic mode was used to study the interaction of cyt c with various surfaces. For this purpose, changes in the resonant frequency, Δ<i>f</i>, and dissipation, Δ<i>D</i>, were determined. The strongest interaction of cyt c was observed with sensors based on specific DNA aptamers that were accompanied by a decrease in frequency and an increase in dissipation. The limit of detection (LOD) for this aptasensor was established as 2.89 ± 0.12 nM. The interaction of cyt c with supported lipid films also resulted in a decrease in resonant frequency, but significant changes occurred only in the µM concentration range of cyt c. Changes in dissipation were much lower in comparison with aptamer-based surfaces, which suggests a weaker contribution of cyt c adsorption to the viscosity.
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